Report  No.  II68-1
         ASSESSMENT OF AIRCRAFT
      EMISSION CONTROL TECHNOLOGY
Northern Research  iiiid Engineering Corporation
          e, Massachusetts                London, England

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                                           Copy No. 218
                   Report No. 1168-1
            ASSESSMENT OF AIRCRAFT
         EMISSION CONTROL TECHNOLOGY
                     by
E. K. Bastress, R. C. Baker, C. F. Robertson,
        R. D. Siegel, and G. E. Smith
              Prepared for the
           Office of Air Programs
       Environmental Protection Agency
          (Contract No. 68-0^-0011)
NORTHERN RESEARCH AND ENGINEERING CORPORATION
              219 Vassar Street
       Cambridge, Massachusetts  02139
               September, 1971

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          This work was carried out under the direct ion.of Dr. D. M. Dix
with Dr. E. K. Bastress assuming project responsibility.  Other principal
participants  in this program were Dr. R. C. Baker, C. F. Robertson,
Dr. R. D. Siegel, and G. E. Smith.
          The Project Officer for this program was Mr.  Charles Gray, Jr.,
of the Division of Emission Control Technology, Mobile  Sources Pollution
Control Program, Office of Air Programs* Environmental  Protection Agency.

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                            ACKNOWLEDGEMENTS

          Portions of the information used in this program were provided
by the following organizations:
          Aircraft Engine Group
          General Electric Company
          Pratt & Whitney Aircraft Division
          United Aircraft Corporation
          Avco-Lycoming Division
          AVCO Corporation
          American Air!ines
          Massachusetts Port Authority
          Transportation Systems Center
          U. S. Department of Transportation
          Bureau of Mines
          U. S. Department of Interior
          Federal Aviation Administration
          U. S. Department of Transportation
          U. S. Department of Defense
          Aero Propulsion Laboratory
          U. S. Air Force
          Rolls-Royce (1971) Ltd.
          Silent Hoist and Crane Company
          AiResearch Manufacturing Company
          Beckman Instruments, Inc.
          Lockheed-California Company
          Lewis Research Center
          National Aeronautics and Space Administration
          Naval Air Propulsion Test Center
          U. S. Navy
          Southwest Research Institute
          Continental Motors Division
          Teledyne Corporation
          Engelhard Industries Division
          Engelhard Minerals and Chemicals Corporation
          Van Dusen Aircraft Supplies, Inc.
          Curtiss-Wright Corporation

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                           TABLE OF CONTENTS

INTRODUCTION	.....".	   1
          Background 	   1
          Objectives	.  .  .  .	   2
          Methodology	   k
          Pollutants Considered	   6
          Report Contents	   7
SUMMARY OF RESULTS	   8
          Emission Control by Engine Modification	 .   8
          Emission Control by Ground Operations Modifications. ...  14
          Emission Measurement Technology	16
CONCLUSIONS	  19
AIRCRAFT ENGINE CLASSIFICATION 	  22
          Engine Population	22
          Engine Classification	23
EFFECTIVENESS OF CONTROL METHODS:  ENGINE AND FUEL MODIFICATIONS . .  25
          Introduction 	  	 .......  25
          Control Methods	25
          Control Method Effectiveness 	  35
IMPLEMENTATION COSTS AND TIMES OF CONTROL METHODS:
ENGINE MODIFICATIONS 	  38
          Engine Classification and Control Method Definition. ...  38
          Cost and Time Analysis Procedures	39
          "Development" Cost and Time Analysis	40
          Implementation (Retrofitting) Cost and Time Analysis ...  42
          Total Development and  Implementation Cost •  •
          and Time Analysis	45
          Final Cost and Time Results for Current
          Engines in Service	47
          Total  Implementation Cost/Engine for
         . "Production" Engines 	 	  48
          Control Methods Applicable to Future Engines 	  48

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EFFECTIVENESS OF CONTROL METHODS:  GROUND OPERATIONS
MODIFICATIONS	5**
          Introduction 	  54
          Control Method Effectiveness	5*t
          Conclusions	60
IMPLEMENTATION COSTS AND TIMES OF CONTROL METHODS:
GROUND OPERATIONS MODIFICATIONS	61
          Basis for Estimates	61
          Discussion of Results	6k
EMISSIONS MEASUREMENT	72
          Introduction 	  72
          Test Procedures	73
          Exhaust Sampling Techniques	73
          Instrumentation	76
          Recommendations	78
REFERENCES	81
TABLES		90
FIGURES	 15^
APPENDIX - INSTRUMENTATION	172

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                            LIST OF TABLES
Table   1:
Table   2:


Table  3A:


Table  3B:


Table   k:

Table  5A:


Table  SB:

Table   6:

Table   7:

Table   8:

Table   9:

Table  10:


Table  11:


Table 12A:


Table 12B:

Table 12C:


Table 12D:

Table 12E:


Table 12F:


Table 12G:


Table  13:
Aircraft Classification System .... 	  91

Turbine Engines in the U. S. Air Carrier
Fleet (January, 1970)	93

Total Engines in the U. S. General Aviation
Fleet (Turbine Engines) (January, 1970)	95

Total Engines in the U. S. General Aviation
Fleet (Piston Engines) (January, 1970) 	  96

Total Engines in the U. S. Military Fleet
(Turbine and Piston Engines) (January, 1970) 	  98
Total Engines in the U. S. Civil Helicopter and V/STOL
Fleet (Turbine and Piston Engines)  (January, 1970) . . 100

Total Engines in the U. S. Civil Helicopter and V/STOL
Fleet (Turbine and Piston Engines)  (January, 1970) . . 101
Engine Classification	102

Aircraft Turbine Engine Classification System	 103

Aircraft Piston Engine Classification System ..... 107

Aircraft Turbine and Piston Engine Classification
Summary	109

Emission Control Methods:  Modification of
Turbine Engines	 110
Emission Control Methods:  Modification of
Piston Engines 	 Ill

Emission Control Method Effectiveness:  Turbine
Engine Modifications 	 112

Emission Control Method Effectiveness:  Turbine
Engine Modifications 	 113

Emission Control Method Effectiveness:  Turbine
Engine Modifications	]]J*

Emission Control Method Effectiveness:  Turbine
Engine Modifications 	 115
Emission Control Method Effectiveness:  Turbine
Engine Modifications 	 116
Emission Control Method Effectiveness:  Turbine
Engine Modifications 	 117
Emission Control Method Effectiveness:  Turbine
Engine Modifications 	 118
Current Uncontrolled Emission Rates - Piston
Engines (lb/1000 Ib-fuel)	i  -,
                    -  iii -

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Table  \k:  Emission Control Effectiveness:  Piston
            Engine Modifications 	 120

Table  15:  Total Aircraft Turbine Engine Development
            Cost/Time Sample Calculation 	 121

Table  16:  Turbine Engine Development Cost/Time Sample
            Calculation for Separate Categories; Air Carrier,
            General Aviation, Military 	 122

Table  17:  Total Aircraft Piston Engine Development
            Cost/Time Sample Calculation 	 123

Table  18:  Piston Engine Development Cost/Time Sample
            Calculation for Separate Categories; Air Carrier,
            General Aviation, Military	I2*t
Table  19:  Total Aircraft Turbine Engine Implementation
            Cost/Time Sample Calculation 	 125

Table  20:  Turbine Engine Implementation Cost/Time Sample
            Calculation for Separate Categories:  Air
            Carrier, General Aviation, Military	 126

Table  21:  Total Aircraft Piston Engine Implementation
            Cost/Time Sample Calculation 	 127

Table  22:  Piston Engine Implementation Cost/Time Sample
            Calculation for Separate Categories:  Air
          .  Carrier, General Aviation, Military	128

Table  23:  Turbine Engine Cost Scaling Parameter Summary	 129

Table  2k;  Final Cost/Time Results for Total Turbine
            Engine Population	130

Table  25:  Final Cost/Time Results for Turbine Engine
            Population by Separate Categories:   Air
            Carrier, General Aviation, Military	131

Table  26:  Final Cost/Time Results for Total Piston
            Engine Population	133

Table  27:  Final Cost/Time Results for Piston Engine
            Population by Separate Categories:   Air
            Carrier, General Aviation, Military	13^

Table  28:  Implementation Cost/Time Sample Calculation
            for "Production" Turbine Engines of Existing Design. . 135
Table  29:  Implementation Cost/Time Sample Calculation
            for "Production" Piston Engines of Existing Design . . 136

Table  30:  Implementation Cost/Time Final  Results for
            "Production" Engines - Turbine and Piston Engines
            of Existing Design	137
Table  31:  Cost/Time Results for Future Turbine Engines 	 138

Table  32:  Reduction in Emission Factors for 100 Per Cent
            Increase in Idle Power	139

                                 - iv -

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Table  33:  Reduction in Taxi and Idle Emissions Resulting
            from the Use of the Minimum Number of Engines
            for Taxiing	140

Table  34:  Total Aircraft Emissions for 1970 at Los Angeles
            International Airport	141

Table  35:  Percentage Reduction in Total Aircraft Emissions
            Due to Avoiding Runway Delays at Los Angeles
            International Airport	142

Table  36:  Emissions for Taxi Mode	143

Table  37:  Percentage Reduction in Total Aircraft Emissions
            Due to Elimination of the Taxi Mode at Los Angeles
            International Airport	144

Table  38:  Pollutants from Auxi 1 iary Power Unit	145

Table .439:  Comparative Reductions Resulting from Control
            Methods Applied to Los Angeles Internationa]
            Airport	146
Table  40:  Basis for Estimating Costs of Ground Operation
            Changes at Los Angeles International Airport 	 14?
Table  41:  Implementation Cost and Time for Operations Changes
            at Los Angeles International Airport 	 ... 148
Table  42:  Factors Affecting Feasibility of Operating
            Changes at Los Angeles International Airport 	 149

Table  43:  Current Ranges of Aircraft Engine Exhaust
            Emission Concentrations.	 ... 150

Table  44:  Instrumentation Accuracy Requirements for Exhaust
            Gas Analysis	151

Table  45:  Exhaust Gas Analysis Methods in Use at 17
            Organizations	
                                 - v -

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                            LIST OF FIGURES


Figure   1:  Turbine Engine Emission Data, Carbon Monoxide 	 155

Figure   2:  Turbine Engine Emission Data, Total
             Hydrocarbons (as CH. )	156

Figure   3:  Turbine Engine Emission Data, Nitrogen
             Oxides (as NO^)	157

Figure   4:  Turbine Engine Emission Data, Dry Particulates.  .... 158
Figure   5:  Emission Control Cost/Time Model for Typical
             Aircraft Engine Family Currently In-Service 	 159
Figure   6:  Summary of Total Turbine Engine Population
             Cost/Time Analysis Procedure	160
Figure  6A:  Summary of Total Piston Engine Population
             Cost/Time Analysis Procedure	161

Figure   7:  Summary of Air Carrier Turbine Engine
             Population Cost/Time Analysis Procedure 	 162

Figure   8:  Summary of General Aviation Turbine Engine
             Population Cost/Time Analysis Procedure 	 163

Figure   9:  Summary of Civil Aviation Turbine Engine
             Population Cost/Time Analysis Procedure 	 164

Figure  -9A:  Summary of Civil Aviation Piston Engine
             Population Cost/Time Analysis Procedure 	 165

Figure  10:  Summary of Military Aviation Turbine Engine
             Population Cost/Time Analysis Procedure 	 166

Figure 10A:  Summary of Military Aviation Piston Engine
             Population Cost/Time Analysis Procedure 	 167
Figure  11:  Implementation Cost Per Engine Versus Normalized
             Cost Parameters for Turbine Engine	168

Figure  12:  Fuel Flow Plotted Against Power for
             Each Aircraft Class	169

Figure  13:  CO Emission Factors Plotted Against Power
             for Each Aircraft Class	170

Figure  14:  Hydrocarbon Emission Factors Plotted Against
             Power for Each Aircraft Class	171
                                  -  vi  -

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                             INTRODUCTION

Background
          An awareness of air pollutant emissions from aircraft developed
in the late 1950's with the introduction into service of turbine-engine
aircraft.  Visible exhaust plumes from turbojet engines and increased
levels of exhaust odors at airports gave rise to complaints against
these perceptible manifestations of aircraft emissions.  These complaints,
in turn,  stimulated investigations by public health agencies into the
nature and extent of aircraft emissions, and these investigations have
continued unabated in the intervening years.
          In 1968, Northern Research and Engineering Corporation con-
ducted a survey of information on aircraft emissions and their control.
This investigation was sponsored by the National Air Pollution Control
Administration and resulted in a comprehensive  report on the
nature and control of aircraft emissions (Ref 11).  This investigation
was directed primarily at an assessment of the extent or magnitude of
aircraft emissions, and identification of approaches to reducing emission
rates.  The report represents the state of our understanding of the subject
in 1968,  and identifies the principal sources of information on aircraft
emissions which existed at that time.
          Since 1968, several organizations have been active in further
investigations of various aspects of aircraft emission control.  The NREC
staff, in 1969, conducted a detailed analysis of the implementation times
and costs of controlling visible smoke emission by "retrofitting" low-
smoke combustors  in existing turbine engines (Ref 2).  In 1970, Scott
Research Laboratories completed an investigation of emissions from aircraft
piston engines which resulted in the first significant source of information
on this subject (Ref 3)•  In '971, a series of  papers on aircraft'emissions
were presented at a conference on "Aircraft and the Environment" sponsored
by SAE and DOT (Ref *+), and the results of this conference were summarized
in a paper by Paul 1 in (Ref 5).  These investigations (Refs 2 through 5),
in our opinion, have produced the most significant contributions to the  .
over-all  subject of aircraft emissions since 1968.  There have, of course,

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been many advances in more specific areas of emission control.  Many of
these works will be cited later in this report.
          The investigation described in this report was initiated in
response to requirements of the Clean Air Amendments of 1970.  This
act calls for the establishment of aircraft emissions standards as
specified in Section 231 of the Act.   Specifically, this section calls
for the investigation of emissions of air pollutants from aircraft to
determine:
          1.  The extent to which such emissions affect air quality in
              air quality control regions throughout the United States.
          2.  The technical feasibility of controlling such emissions.
Based upon the  information generated under such a study, the Environ-
mental Protection Agency is required to propose emissions standards
applicable to any class or classes of aircraft which cause or contribute
to air pollution which endangers the public health or welfare, and to
establish an implementation schedule commensurate with available tech-
nology and reasonable cost of compliance.
          In order to carry out the above requirements, the responsi-
bilities within the Environmental Protection Agency were divided.  The
Bureau of Air Pollution Sciences, Office of Research and Monitoring,
had primary responsibility to assess the impact of aircraft emissions
on air quality.  The Mobile Sources Pollution Control Program,
Office of Air Programs, independently initiated a study to assess the
technical feasibility of controlling aircraft pollutant emissions and
the costs associated therewith.
          This  report has been prepared for the Mobile Sources
Pollution Control Program and  is concerned with aircraft emission
control technology.  A parallel investigation of the impact of aircraft
emissions has been conducted by NREC for the Bureau of Criteria and
Standards.  The results of the impact investigation are contained in a
companion report (Ref 6).

Object ives
          The over-all objective of the two investigations was to provide
information necessary for establishing standards on emissions from aircraft

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activities.  The information required for this purpose falls into the
following categories:
           1.  Methods for controlling emissions from aircraft activiti.es.
                                           t
          2.  Instrumentation requirements for measuring aircraft emis-
              sions.
          3-  Rates of emission of various pollutants at airports from
              aircraft activities.
          k.  Impact of emissions from aircraft activities in airport
              vicinities.
           Information on emission control method.s is necessary to determine
the levels to which it is feasible to reduce aircraft emissions.   The re-
sults of an earlier NREC study (Ref 1) indicated that practical  control
approaches include modifications of aircraft engines, fuels, and
ground operational procedures.  Thus, an assessment of control methods
must be concerned with each of these categories of approaches.  In assess-
ing the feasibility of a control method, three factors must be explored:
the cost of utilizing the method, the effects of the method on the func-
tioning or capacity of the aircraft system, and the effectiveness of the
method in  reducing emissions.
           Information on emission measurement instrumentation is necessary
to assure  that aircraft emissions can be measured with the accuracy and
sensitivity necessary to enforce the desired standards.  Measurements will
be required for engines operated under test conditions in the laboratory
and engines being operated while installed in all types of aircraft.  It
is not necessary, for the purpose of enforcing emission standards, that
measurements be taken on engines in moving aircraft, either on the ground
or in fIight.
           Pollutant emission rates at airports are not required specifi-
cally in the establishment and enforcement of air quality standards.
Presumably, such standards will be based upon instantaneous or cumulative
emissions  from  individual aircraft, or aircraft engines, and associated
auxiliary  equipment.  However, the total emission rate at an airport is
an important intermediate quantity required in relating the impact of
aircraft emissions to aircraft emission rates and activity levels.  Also,
the total  airport emission rate, is used as a gross measure of the importance

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 of  an airport  as  an  emission  source  in  the  community.
           Information on the  impact of aircraft emissions is necessary to
determine  the  levels to which it is necessary to reduce emission rates in
order to prevent adverse health effects, property damage, or undue annoy-
ance.  This information must be in the form of correlations between pollu-
tant  levels in the airport neighborhood and the rates of emission at the
ai rport.
           The  specific objectives of this investigation of emission control
technology were:
           1.   To  identify methods of controlling aircraft emissions through
               modifications of engines, fuels, and ground operations.
                                       j
           2.   To estimate the effectiveness of these control methods
               in  reducing aircraft emission rates.
           3«   To estimate the times and costs of implementing these control
               methods.
          k.   To assess the technology of emission measurement as applied
               to aircraft engines, and to identify areas where advance-
              ments  in instrumentation or test procedures are required.

Methodology
          The  program has consisted essentially of independent investiga-
tions of the following topics:
           1.   Emission control by engine modification.
          2.   Emission control by fuel modification.
          3*   Emission control by ground operations modification.
          4.   Emission measurement.
The investigation of fuel modifications was discontinued after prelim-
inary analysis indicated that no significant reductions in emiss.ions can
be achieved by modifying fuels,  except for reductions in sulfur or lead
which result in proportionate reductions of S02 and lead emissions.
          Engine modification control methods were identified through
reviews of earlier work (e.g.  Ref 1)  and through discussions with engine
manufacturers.  A list of specific control methods was formulated on the
basis of preliminary analyses which indicated that each method was feasibile

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 and offered a significant reduction in one or more emission classes.
 Feasibility was based on  the  following  factors:
           1.  No  reduction  in engine  reliability  (safety).
           2.  Little or no  reduction  in engine performance  (power-weight
              ratio).
           3«  Reasonable  cost of  implementation.
 The  preliminary list of control methods was then  subjected  to more detailed
 analysis of control effectiveness and  implementation costs.  The results
.of  the  effectiveness analysis were  supplied as  input  information to the
 parallel study of impact  of aircraft  emissions.   The predicted effective-
 ness of each  control method  in  reducing impact at airports  is reported in
 Reference  6.
           Ground  operations modification control methods were evaluated
 in a similar  manner.  Specific  methods were identified through discussions
 with engine manufacturers,  airlines,  and airport operators.  These methods
 also were  subjected to analyses of  effectiveness and costs, and their
 effectiveness in  reducing emission  impact  also has been evaluated  in the
 impact  study.
           The emission measurement  technology assessment consisted essen-
 tially  of  the following steps:
           1.  Analysis of the accuracy  and sensitivity requirements of
              measurement instruments  required for current  and future
              emission  levels from  aircraft engines.
           2.. Compilation of  information on measurement equipment cur-
              rently used by  engine manufacturers and air quality
              control agencies,;and equipment available from instrument
              manufacturers;
           3.  Review of factors affecting  the design and selection of
              measurement equipment,  and the  specification  of test pro-
              cedures.
 In  this task, full advantage  was  taken  of  the results of other groups which
 have been  active  in studying  various  aspects of measurement of aircraft
 emissions.

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Pollutants Considered
          In this program, consideration has been given, in varying degrees,
to the following pollutant classes:
          Emission constituents:
               Carbon dioxide (C02)
               Carbon "monoxide (CO)
               Nitric oxide (NO)
               Nitrogen dioxide (NOz)
               Organic constituents
                    Total hydrocarbons (THC)
                    Reactive hydrocarbons (RHC)
                    Aldehydes (ALD)
               Dry particulates (DP)
               Sulfur dioxide (S02)
          Sensory effects:
               Visible smoke
               Odor
Contributions to these pollutant classes have been considered from the
following aircraft sources:
          Engine exhaust
          Crankcase blow-by
          Auxiliary power unit exhaust
          Fuel drainage
          Evaporative emissions
The assessment of measurement technology included all of these emissions
except reactive hydrocarbons (RHC).  This class is not well defined at
the present time.
          In the evaluation of emission control methods involving engine
modifications, the following emission classes were considered:
          Carbon monoxide (CO)
          Nitrogen oxides (NOx)
          Total hydrocarbons (including drained fuel)
          Dry particulates  (including smoke)
Reactive hydrocarbons and aldehydes were not included since no correlations

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exist between engine design characteristics and emission rates for these
classes, and no control methods have been developed.   S0_ emissions were
not considered since these are directly related to the sulfur content
of the fuels burned and are independent of engine characteristics.
          In the evaluation of emission control methods based on ground
operations modifications, reductions in RHC, ALD, and SO. emissions were
considered in addition to those considered with engine modifications.

Report Contents
          The principal results and conclusions of the program are summar-
ized in the following sections of the report.  Detailed descriptions of
the methodology and results of the analyses of control methods and measure-
ment methods are contained in later sections of the report.
          Background information in each of the analysis areas is rather
limited.  For further  information on the nature of- aircraft engines and
their emissions, an earlier NREC report  (Ref 1)  is suggested.  The companion
report on impact of aircraft emissions  (Ref 6) also is recommended as a
sourcesof related  information.

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                          SUMMARY OF RESULTS

Emission Control by Engine Modification

                         Engine Classification
          To facilitate analyses of engine modifications, aircraft engines
have been categorized according to their thrust or power level as follows:
Engine Class        Engine Type        Power Range (Ibf-thrust or ESHP)
     Tl               Turbine               Less than 6000
     T2               Turbine               6000 to 29..000
     T3               Turbine               Greater than
                                            29,000
     PI               Piston                (Includes all opposed
                                            configuration engines)

This classification system, although it is based simply upon thrust
level, effectively separates engines of similar emission potential.
Also, the effectiveness and costs of control methods can be considered
to be similar for all engines within each class.  Thus, the classification
system has been particularly useful for this program and may also provide
a rational basis for the definition of emission control standards.  Specific
engine families within each class and their characteristics are discussed
 in the report- sect ion entitled AIRCRAFT ENGINE  CLASSIFICATION.
                         9
                         /
                       Emission Control Methods

                            Turbine Engines
          Six control methods involving engine modifications have been
 identified which are applicable to existing turbine engines.  The control
methods and the pollutant classes which they are  intended to control are
as follows:
      Control Method                        Pollutant Classes Controlled
 Combustor  redesign  (minor)                    CO, THC, NOx, DP, Smoke
 Combustor  redesign  (major)                    DP, Smoke

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      Control  Method                        Pollutant Classes Controlled
Fuel drainage control                         THC
Divided fuel supply                           CO, THC
Water injection                               NOx
Compressor air bleed                          CO, THC
The first control method consists of simple modifications of the combustor
and fuel nozzle to reduce all emission rates to the best levels currently
attainable within each engine class.  The degree of control attainable
depends upon the performance of specific engines with respect to those
engine  in the same class demonstrating best emission performance.  Each
of the other control methods is more specifically directed at one or two
pollutant classes.
          Two control methods have been identified which are considered
to be applicable only to future engines as the design concepts  involved
could not readily be incorporated into engines already designed.  These
control methods are:
      Control Method                        Pollutant Classes Controlled
Variable-Geometry Combustor                   CO, THC, NOx,; DP, Smoke
Staged  Injection Combustor                    CO, THC, NOx, DP, Smoke
These control methods involve advanced combustor design concepts and,
as  indicated, would  be effective  in controlling  all pollutant classes
considered.
          The actual reduction  in emission  rate  achieved through the use
of a control method  varies with  the pollutant considered,  the engine
class,  and  the engine operating mode.  Estimates of  the- effectiveness
of each control method have  been made for all combinations  of  these
factors and are  presented  in the  report section  entitled EFFECTIVENESS
OF  CONTROL METHODS:  ENGINE  AND  FUEL MODIFICATIONS.

                             Piston  Engines
          Seven  control methods  have been  identified which  are  considered
to  be  feasible for  application  to existing  aircraft  piston engines.

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                                                                      10

These methods have been developed primarily for the control  of THC and
CO emissions from automobile engines.   Control  methods for NOx emissions
have not been included since aircraft  piston engines of current design
operate at rich fuel-air ratios and,  as a result,  their NOx emission
rates are very low compared to those  from automobile engines.   The
installation of any of the THC and CO  control  methods would not be
expected to increase NOx emissions significantly.   The control methods
applicable to existing piston engines  are as follows:
        Control Method                      Pollutant Classes  Controlled
Simple Air Injection                                   CO, THC
Thermal Reactor                                        CO, THC
Catalytic Reactor                                      CO, THC
Direct-Flame Afterburner                               CO, THC
Water  Injection                                        CO, THC
Positive Crankcase Ventilation                         THC
Evaporative Emission Control                           THC
With regard to future piston engines,  various design modifications can
be  introduced for reducing emission rates.  For this study, these modi-
fications have been regarded collectively as one control method as follows;
        Control Method                      Pollutant Classes  Controlled
Engine  Redesign                                        CO, THC
The modifications included  in  this control method would be similar to modi-
fications which have been  introduced  in  recent years by automobile manu-
facturers to achieve moderate  reductions  in exhaust emissions.  They do
not .include the control methods  listed above for existing engines, but
may  include auxiliary devices  required for NOx control.   Estimates of
effectiveness  for piston engine control  methods are presented  in  the
report  section entitled EFFECTIVENESS OF CONTROL METHODS:  ENGINE AND
FUEL MODIFICATIONS.

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                                                                      11

                    Implementation Costs and Times^

                           Existing Engines
          The cost and time requirements of applying each control method
applicable to existing engines have been estimated.   These estimates are
of a preliminary nature and are intended to indicate the order of the
costs involved in controlling emissions from all civil and military
aircraft.  Cost and time requirements have been estimated separately
for control method development and implementation.  Development  includes
all effort required through certification of the control method for a
specific engine family and tooling for production.  Implementation in-
cludes initial installation of the control method on all engines of a
family,  and any additional effort or materials costs associated with
the control method throughout the remaining service life of the engine.
          Since very few of the control methods have actually been
developed or applied to aircraft engines, and since many factors affect
total implementation costs, many uncertainties are involved in the
estimates.  The estimates of development costs and times are considered
to be reliable.  Their accuracy is judged to be within a factor of about 2.
That is, the true costs and times of control method development probably
lie within a range between 50 and 200 per cent of the estimates.  The
estimates of implementation costs are considered to be less reliable.
The cost and service life of a modified engine component cannot be
predicted accurately.   Yet these factors strongly affect the cumulative
costs of operating and maintaining the modified engine.  This uncertainty
is unfortunate since the implementation costs could be far greater than
the development costs for some control methods.  Thus, the estimates of
implementation costs can only be regarded as indicative of cost penalties
which might be involved with control method implementation.
           In the table below, estimates are given of the development
time, development costs; and implementation cost for application of
each control method to the current population of civil engines.

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                                                                             12
                                   Turbine Engines
        Control Method

Combustor redesign (minor)
Combustor redesign (major)
Fuel drainage control
Divided fuel supply
Water injection
Compressor air bleed
Development
Time
(vears)
2
5
3
5
2.
4
1/2 - 5
- 7 1/2
- 5 1/2
- 7 1/2
1/2 - 4
- 6 1/2
Development
Cost
(106 dollars)
37
74
35
84
25
90
             Implementati on
                 ,Cost
              (10b dollars)
                   343
                   589
                    44
                   102
                   151
                    58
                                   Piston Engines
                                     1  1/2 - 3
                                     3-6
                                     21/2-5
                                     3 - 6
                                     1  1/2-3
                                     1  - 2
                                     1  1/2-2 1/2
 9
25
22
25
 9
 4
 4
165
424
535
42**
 81
 94
269
Simple air injection
Thermal reactor
Catalytic reactor
Direct-flame afterburner
Water  injection
Positive crankcase ventilation
Evaporative emission control
       The development times listed above are the times required to reach the
       point where installation of the control methods in existing engines could
       beg i n.  Installation of any control method in all  existing engines would
       reguire an additional time period which is dependent primarily on the
       availability of engine maintenance facilities.  The minimum time for
       implementation is estimated to be 2 1/2 years for turbine engines and 5
       years for piston engines.
                 As indicated, the costs estimates are based upon the current
       engine population.  Since this population will be different by the time
       any of the control methods could be developed, the implementation costs
       also will  be different.  This difference represents an additional source
       of uncertainty with regard to implementation costs.
                 To put the implementation costs in a different perspective,
       they may be.expressed as fractions of total engine costs.  For a typical
       Class T2 (turbine) engine, the cost of installing and maintaining control

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                                                                      13

methods ranges from $4500 to $61,000, assuming a 10-year engine life.
Based on a total engine cost of $250,000, these control method impler
mentation costs represent 2 to 25 per cent of the total engine cost.
For a typical piston engine, control method implementation costs
estimates range from $600 to $4000, also based upon a 10-year engine
life.  For a total engine cost of $6000, these implementation costs
represent 10 to 65 per cent of the total engine cost.
          The turbine engine cost and time estimates were developed by using
the application of low-smoke combustors to the JT8D engine family as a refer-
ence case.   Requirements for this case, which is considered to be a
minor combustor redesign for a class T2 engine,  were estimated in detail
in 1969 (Ref 2).  Requirements for other control  methods were determined
essentially by proportioning the costs and times according to the complexity
of the method with respect to the reference case.   Requirements for other
engine classes were determined by using appropriate scaling factors and
again using the reference case as a basis.
          The piston engine time and cost estimates are based largely on
experience to date with emission control from automobile engines.
          The methodology used in developing these estimates and the
various elements of the total cost and time estimates are discussed
later in this report.  Similar cost estimates are presented for
mil!tary engines.

                            Future Engines
          Cost estimates also have been developed for incorporation of
emission controls  in future engines, that is, engines which have not
yet been developed.  These estimates have been defined only as fractions
of total engine cost since no reasonable basis is available for estimating
the numbers of engines which would be affected.
          Emission control in turbine engines attained through the use
of advanced combustor design concepts  is estimated to represent an
increase in total engine cost of 3 to 4 per cent.   Emission control  in
piston engines achieved by engine design modifications probably would
not result in any significant increase  in engine cost.  However, if

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 greater control  of  emissions  is  required  than  can  be  achieved  by  engine
 design modifications,  one  or  more  of  the  control methods applicable  to
 existing engines will  be necessary.   The  costs  of  these control methods,
 which involve the addition of auxiliary devices such  as thermal reactors,
 will  be significant—  probably in  the range  of  5  to  10 per  cent of total
 engine cost.
           These  cost estimates represent  the increased costs of new
 engines with  emission  controls installed.   It  is  reasonable to expect
 additional  continuing  costs for  maintenance  of  the control  methods.
 These maintenance costs would be similar  to  those  for modification of
 existing engines which were estimated" to  represent 2  to 25  per cent  of
 total turbine engine costs and 10  to  65 per  cent  of  total  piston  engine
 costs.

 Emission Control by Ground Operations Modification

                    Definition of  Ground  Operations
           The cycle of operations  performed  by  an  aircraft  during its
 arrival at  and departure from an airport  can be defined quite  precisely
 since most  of these operations are prescribed  by  airport or aircraft
 operating procedures.   Characteristic operating or LTD  (landing-take-off)
 cycles have been defined for various  classes of aircraft for purposes
 of estimating pollutant emissions  (Refs  1,  3,  and  6).
           The LTO.cycle can be separated  logically into flight and
 ground operations.   Flight operations include the  approach  and climb-
 out modes as  well as  the  landing and  take-off runs,  even though  the
 latter occur  on  the ground.  Ground operations  include  the  taxi  and  idle
 modes of the  cycle  and, for purposes  of  this study,  all servicing and
 support operations  which  involve emission sources.  This separation  is
 logical for two reasons.   First, flight operations as defined  here are
 those which cannot  readily be modified as an approach to reducing pollutant
emissions.   Second, flight operations are conducted  almost  entirely
 with aircraft engines  at full or part power, and under  these conditions,

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                                                                      15
pollutant emission rates are quite different from those at the low power
levels which are characteristic of ground operations.   Aircraft ground
operations contribute substantially to concentrations  of CO and THC
which exist at air carrier airports because of the relatively high emis-
sion rates of these pollutant classes at low engine power levels,
and because ground operations are largely confined to limited areas
within the airport boundaries.

                       Emission Control Methods
          Seven methods have been identified which offer some degree of
control of CO and THC emissions at air carrier airports by modification
of ground operational procedures.  These methods, which under preliminary
analysis were judged to be feasible, are as follows:
          1.  Increase engine speed during  idle and taxi operations.
          2.  Increase engine speed and  reduce number of engines operating
              during idle and taxi.
          3.  Reduce idle operating time by controlling departure  times
              from gates.
          4.  Reduce taxi operating time by transporting passengers to
              aircraft.
          5«  Reduce taxi operating time by towing aircraft between
              runway and gate.
          6.  Reduce operating  time of aircraft auxiliary power supply
              by  providing ground-based  power  supply.
          7-  Manually remove fuel from  fuel drainage  reservoirs.
The first two methods reduce emissions by  requiring engines to be  operated
at more efficient power settings, and  the  next four methods reduce emis-
sions by  reducing operating time of either main or auxiliary engines.  The
effectiveness of  these methods  in reducing  emissions varies considerably,
but certain methods  (2 and 5)t  if implemented, would reduce total  CO
and THC emissions to approximately one-half their current levels at air
carrier airports.                   	
          The control methods listed above are not, in general, applicable
to small, piston-engine aircraft, and, therefore, do not offer means for
controlling emissions at general aviation airports.  Delay times at take-off

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                                                                             16

       are significant at some general  aviation airports.   However,  general  aviation
       operations are, not sufficiently  controlled for a system of controlled gate
       departures or engine start-up to be effective in reducing delays.  If'emissions at
       general  aviation airports are to be controlled,  control  methods involving engine
       modifications must.be/used.

                           Implementation Costs and Times
                 The cost and time requirements of the control methods
       involving ground operations modifications have been estimated for one
       specific airport (Los Angeles International).  These estimates involve
       many uncertainties and, therefore, must be regarded as preliminary.
       The estimates are considered to be accurate within a factor of 2.   That
       is the true costs and times of implementation at the airport considered
       probably are within a range of 50 to 200 per cent of the estimates.
       The estimates are as follows:

                                                                       Annual Operating
         Control Method                 Time         Initial Cost       .   Cost Change
                                        (years)       (1Qb dol llrl)        (10-6 dol lars)
1.  Increase engine speed                  0               0                  8.5
2.  Increase speed, reduce number        0.3-              0                 -3.0
3.  Control gate departure                 5              15                 -1.6
k.  Transport passengers                 2-5              65                  5.0
5.  Tow aircraft             '             1             1.2                  M7
6.  Reduce APU operation                 0.5             1.3                  1.5
7.  Manual drainage                     .0.5         .   0..04                  3.0
       Implementation of these methods  at other airports would involve  costs of
       the same magnitude.  However, the actual costs would vary with activity
       level  and the present availability of auxiliary equipment.

       Emission Measurement Technology

                            Sampling and Test Procedures
                 Obtaining a representative sample of exhaust gas from  an air-
       craft  engine for analysis of emission rates is not a trivial procedure.

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                                                                      17
The requirement is difficult at the outset  with  turbine  engines  because
of the jet blast environment in which the sampling  equipment  must  be  installed.
Beyond that problem,  the following factors  are all  found to have significant
effects on the composition of the exhaust sample:
          Engine power level
          Timewise and spatial  variations of exhaust  composition  '
          Sampling line diameter, length, material, and  temperature
          Ambient temperature and humidity
          Ambient pollutant  levels
Procedures  for  sampling and analyzing turbine engine exhaust gases have
been  under  development  for  several years by engine manufacturers and
various  government agencies.   More  recently the Society of Automotive
Engineers  E-31  Committee  has been  formed to standardize these procedures.
Standardization of measurement  techniques will minimize the  variations
due to the  factors listed above.  However,  the sources of  error  in collecting
samples  and the variability of  samples among different engines must be
considered  in the establishment of emission control standards.
          Sampling requirements for aircraft piston engines can be expected
to be similar to those for  automobile engines.  There are no apparent
factors  which would cause variability in exhaust samples beyond those
factors  already recognized  with automobiles.

                   Emission  Measurement  Instrumentation
            Measurement  of concentrations of most pollutants  in  exhaust
  samples from aircraft  engines is  generally within the  capabilities of
  existing  instruments,  and  will  remain  so  even with modifications  of
  engines to reduce emission rates.   The  ranges of accuracy and  sensi-
  t.ivity  which are  required  for aircraft  emission measurements are  dis-
  cussed  later in  this  report.
           The various types of instruments which are available and in
 current use for aircraft emission measurement have been reviewed.
  Instruments which appear to be most suitable for measurement of turbine
 engine  emissions at the  present time are as follows:

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                                                                      18
        Pollutant Class                 Instrument Type
          CO and C0_           Non-dispersive infrared (NDIR)
          THC                  Heated flame.ionization
          NO                   Chemiluminescence
          HO                   Non-dispersive ultraviolet (NDUV)
          Smoke                SAE Smokemeter (ARP 1179)
          Particulates         None
          S0?                  Determined from fuel analysis
          Aldehydes            3-MBTH
          Odor                 Human odor panel
Even though a suitable instrument for particulate measurement is not
available, emission rates of-dry particulates can be estimated on the
basis of smokemeter measurements.  These instruments and alternative
equipment are discussed in the APPENDIX.

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                                                                     19
                             CONCLUSIONS
         From the results of this program,.it is possible to formu-
late conclusions on the costs of various emission control methods and
the effectiveness of these methods in reducing emission rates from air-
craft engines.  The effectiveness of these control methods in reducing
impact of aircraft emi.ssions at airports, is discussed in Reference 6.
         In evaluating control method effectiveness, an order of magnitude
system has been used which is based upon multiple factors of two in
emission rate reduction.  The system is as follows:
                                                           Fraction of
  Order of            •    Emission Reduction              Emission Rate
Effectiveness            Attainable (Per Cent)              Remaining
      1                           50                          0.50
      2                           75                          0.25
      3                           90                          0.10
This system is useful for comparing emission control methods.
          The following conclusions pertain to the control of emissions
from turbine-engine aircraft at air carrier airports:
          1.  First order reductions in CO and THC emission rates can
              be achieved by modifying aircraft ground operations.   If
              these reductions are achieved by modifying engine operating
              power levels and reducing the number of engines used in
              taxi operations, the costs will be negligible, and the
              controls can be implemented  immediately.  A reduction  in
              odor levels at airports should accompany the THC emission
              reduction.
          2.  First and, possibly, second order reductions in CO and
              THC emission rates can be achieved by engine modifications.
              Various alternative methods are available for achieving
              these reductions^ but the cost of implementing any of
              these methods  in the air carrier aircraft  fleet will be
              of the order of 100 million dollars.  The  time required
              to implement any engine modification control method  in
              the air carrier fleet will be from 5  to  10 years.

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                                                                      20
          3.   A second  order  reduction  in  NOx  emission  rates  can  be
              achieved  through  the  use  of  water  injection  during  take-
              off  and climb-out operations.. The  cost of applying this
              control method  to the air carrier fleet  is estimated to
              be approximately  100  million dollars,  and 5  years or more
              will  be required  to  implement the method.  The  degree
              of control  can  be reduced or increased by reducing  or
              increasing  the  rate or duration  of  water  injection.
              However,  the  costs will not  vary proportionately.
          k.   A first order reduction  in particulate emissions can be
              achieved  by major modifications  of  combustors,  but  at  very
              high  cost (600  million dollars)  and with  long  implementation
              times (7  to 10  years).  The  reduction  in  particulate emis-  '
              sions that  would  result from minor  combustor modifications
              would be  less than first  order.
          5.   Visible smoke emission from  turbine engines  can be  sub-
              stantially  reduced by minor  combustor  modifications, and
              such  modifications are being implemented  for certain
              engines.  The additional  cost of eliminating smoke  emission
              from  all  air  carrier  aircraft is estimated to  be of the
              order of  100  million  dollars.
          6.   Second or third order reductions in CO and THC  emissions
              and  first order' reductions in NOx  and  particulate  emissions
              will  accompany  the introduction  of  advanced  combustor
              design concepts in future engines.   Complete elimination
              of visible  smoke and  substantial reductions  of odor will
              accompany these advanced  designs.   Associated  costs will
              be of the order of 3  per  cent of the  total  engine  cost.
              Engines with these features  will not  appear  in service
              before the  late 1970's.
          The following conclusions pertain to the  control of emissions
of piston engines  at general  aviation airports:
          1.  First order reductions in CO and exhaust THC emission rates

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                                                                     21
              can be achieved by simple air injection  systems.   Retro-
              fitting costs  would be of the order  200  million  dollars
              with an implementation time of approximately  6 years.
          2.   Reductions as  high as  third order  in CO  and exhaust  THC
              emissions can  be achieved by more  advanced control methods
              such as thermal reactors  or catalytic reactors.   Retro-
              fitting costs  would be of the order  of 500 million dollars
              and implementation times  would be  8  years  or  more.
          3.   Effectiveness  of THC emission control from piston engines
              can be increased by nearly one order of  magnitude if
              positive crankcase ventilation is  combined with  another
              THC control  method.   PCV  would not be effective  alone
              because of the fuel-rich  operating conditions of aircraft
              piston engines.  The cost of applying PCV  to  existing
              piston engines would be of the order of  100 million  dollars.
          k.   First order reductions in CO and THC emissions can be
              anticipated in future engines by modifications of combustion
              chambers and control systems. .Higher order  reduction can
              be obtained by combining  engine design modifications with
              auxiliary control devices.  Emission control  in  future
              engines may result in increased engine costs  up  to 10
              per cent, depending upon  the degree  of emission  control
              achieved.  Emission control could be incorporated in new
              aircraft piston engines by the mid-1970's  if  initiated now.
          5«   Lead emissions from aircraft piston  engines  could be
              reduced by the use of low-lead or lead-free  gasoline.  These
              reductions couid result directly from the control of lead,
              or could be incidental to  the use of catalytic reactors for
              CO and THC control.  The cost of  low-lead fuels  would be
              approximately  10 per cent  greater than current fuel  costs.
          The technology of emissions measurement  will be  adequate to
support emission control standards requiring first, second, or third
order reductions in emission rates when  sampling and test  procedures have
been refined and standardized.

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                                                                      22
                    AIRCRAFT ENGINE CLASSIFICATION

          The objective of this program is to evaluate the effectiveness,
costs, and time requirements associated with the application of emission
control methods to aircraft engines.  The program is concerned with engines
in current use and engines which will be in service during the next ten
years.  The evaluation of current engines will  be based upon the applica-
tion of control techniques to specific existing engines, whereas the evalua-
tion of future engines will necessarily be based upon projections of future
engine characteristics and populations.  The purpose of this section is
to identify the specific engines which will be included in the analysis of
current engines.
          Engines to be considered  include both turbine and piston engines,
and military as well as civil aircraft engines will  be included.  The
general relationship between the engines and the aircraft classification
system is illustrated in Table il.
          Turbine engines will be considered by "family".  That is, all
engines with the same basic model number, e.g., JT9D or CF6, will be con-
sidered as a single engine type.  This approach is reasonable since, in
most cases, a family of engines has a common combustion system design, and,
hence, the emission characteristics of all engines of the family will be
similar.   This approach also is advantageous in that the number of engines
to be analyzed is limited to a reasonable level.
          Piston engines also will be considered by family wherein the
family designation, e.g.,.10-200 or TIO-360, indicates the use of fuel
injection or turbocharging as well as the engine displacement.

Engine Population
          Engines to be considered  in this analysis are listed  in Tables 2
through 5-  Estimates of the numbers of civil aircraft engines  in current
use are included.  Civil aircraft engines are identified separately as
a-i r carrier or general aviation types in Tables 2 and-:3.  Military
aircraft  engines are identified. in Table k, and current population,
data are provided.  Since this  information on military engines  is not

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                                                                     23
readily available, the results presented must be assumed to be reasonable
approximations.  Helicopter and V/STOL aircraft engines are listed sepa-
rately in Table 5-

Engine Classification
          An engine classification system is required to facilitate the
analyses of effectiveness and costs of specific emission control methods.
This classification should also provide a rational basis for the appli-
cation of emission standards in the event that standards are deemed nec-
ess.ary.  For these purposes, the method of classification should separate
engines into categories wherein all engines have similar emission rates
when normalized according to an appropriate engine size parameter.  Also,
the feasibility and effectiveness of control methods should be similar for
all engines within a single category.
          The classification system which has been adopted is indicated
in Table 6.  Three classes of turbine engines are defined, and all piston
engines are included in a single class.  The system  is effective  in that
it separates engines according to their principal applications, and also
according to certain design characteristics which affect emission rates.
          The small turbine engine class (Tl)  includes most turboshaft
and small turbojet engines used in business aircraft.  These engines should
be considered separately because the relatively small size of the combustor
components  (or  large surface-volume  ratio) makes control of certain emis-
sions more  difficult than with larger engines.
          The next turbine engine class  (T2)  includes most turbojet and
turbofan engines used  in medium to large commercial  aircraft.  The design
characteristics of most of these engines are basically similar.
          The  third turbine engine c-lass (T3)  includes  large turbofan
engines for "jumbo" transport aircraft and  the SST engines currently in
use or under development.  A grouping of the engine.-populations according
to this classification system  is presented  in Tables 7 and 8 for  aircraft
turbine and piston engines respectively.
          Within each of these classes, engine emission  rates can be
expected to be  similar when expressed as an emission index  (lb/1000 Ib-
fuel).  Emission  rates of all pollutants can be correlated effectively

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with fuel rate and other parameters indicating the engine operating
condition such as power level (turbines) or fuel-air ratio (piston
engines).  The emission index is in widespread use as a correlating
parameter, and can be converted readily to other bases such as Ib/hp-hr
or Ib/lb-thrust-hr by using appropriate specific fuel consumption
parameters.
          It is expected that this engine classification will suffice
for purposes of this program and for definition of emission standards
for existing engines.  The system may require modification, however, as
new engines and engine types are developed.
          A summary of the number of engines and engine "families"  in
the total current population and in the categories of air carrier, general
aviation, civil aviation, and military aviation is presented in Table 9
by class.

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                                                                      25
                   EFFECTIVENESS OF CONTROL METHODS:
                     ENGINE AND FUEL MODIFICATIONS
Introduction
          An analysis has been conducted of the technology of emission
control for aircraft engines by means of engine or fuel  modifications.
The purpose of this analysis was to identify specific methods of reducing
pollutant emissions from aircraft, and to indicate the reductions in
emission rates attainable by these methods.   Various engine modifications
have been identified which appear to be feasible, in the sense that they
can be applied to aircraft without degrading engine reliability or
seriously reducing aircraft performance.  The costs of implementing
these control methods also appeared to be within reasonable limits, at
least from preliminary analysis.  However, implementation costs of these
control methods have been evaluated in more detail, and the results of
this cost evaluation are presented in the next section of this report.

Control Methods

                     Turbine  Engine Modifications
          Control methods  considered  feasible  for  turbine engines  are
 listed  in Table  10.  Six methods  are, at  least  in  principle,  applicable
 to  existing  engines  by  retrofitting of  new or  modified parts,  and  to
 engines  currently, in production.  Two..methods  are  considered  to  be
 applicable only  to  future  engines since the modifications  required are
 too extensive  to be  applied  to engines  for which  development  has been
 completed.   These methods  have been  identified in  previous  NREC  studies
 of  gas  turbine combustor design concepts  and  through  discussions with
 engine manufacturers.   The methods are  described  in  the  following
 paragraphs.

                   Minor Combustion Chamber Redesign
          A minor combustion chamber redesign  is defined in this analysis.
as a modification of the combustor liner or fuel nozzle,  or both, not

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                                                                      26

involving a .change in design concept.   Such modifications generally
result in changes in airflow distribution or fuel  spray pattern within
the combustor.   The modification being made currently to JT8D engine
combustors for control of smoke emission is considered to be a minor
combustion chamber redesign.  This control  method  could be used to reduce
all emissions from conventionally designed combustion chambers.  However,
it is not likely that emission rates could be reduced substantially
below the lowest rates which have been achieved in existing engines.

                   Major Combustion Chamber Redesign
          A major combustion chamber redesign is defined as a modification
of the combustor liner and fuel nozzle incorporating an advanced fuel
injection concept.  This modification would involve discarding a con-
ventional liner and pressure-atomizing fuel nozzle combination, and
substituting a new combustion chamber with a carbureting or prevaporizing
fuel  injector.   This type of combustion chamber is being used  in some
engines of recent design  (e.g., CF6 and F101), and its use results  in
substantial reductions in particulate and smoke emissions  (Refs 12 and 13)<
          Other changes  in combustor design could be  included  in this
control method, such as  the substitution of an annular combustor for a
canannular combustor or  the introduction of variable geometry.  However,
changes such as these are not considered feasible for existing engines.

                          Fuel Drainage Control
          This control method  is concerned with the dumping of fuel
which results from the draining of fuel manifolds at engine shut-down  .
and start-up.  At present,  this drained fuel  is collected  in a drainage
reservoir  in many civil  engines, and the reservoir is emptied  automati-
cally during take-off or  climb-out operations.  The drained fuel  is
.discharged to the atmosphere.   In some military engines, the fuel  is
drained directly onto the ground at shut-down and start-up.
          A fuel drainage control system is defined here consisting  of
an automatic transfer system for emptying  the fuel drainage  reservoir
and returning the fuel to one of. the aircraft fuel tanks.   In  the

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•s.
                                                                                    27
               definition  of  this  system  it  is assumed  that drainage of fuel manifolds
               at  engine shut-down and  start-up will continue  to be required.  The
               drainage control  system  would be an  additional  mechanism permanently
               installed  in each engine to eliminate the dumping of drained fuel  into
               the atmosphere or onto the ground.   An analogous control method  is
               defined  later  under ground operations modifications which would serve
               the same function,  but would  consist of  ground-based auxiliary equipment.

                                    Divided Fuel Supply System
                        This control method consists of a modification of  the fuel
               supply system  to  allow some fraction of  the fuel nozzles to  be shut down
               during low  power  operation.   The modification would result  in  increased
               fuel  flow through the remaining fuel nozzles, thereby  increasing  the
               local fuel-air ratio  in  the combustion region.  This  increased fuel-air
               ratio should result in more efficient combustion and  reduced CO and
               THC emissions  during  idle  and taxi operations.  This control method
               is  considered  to  be feasible  for all turbine engines and is  used  currently
               in  some  small  engines.   In engines with  can or  canannular combustors,
               operations  with all fuel nozzles probably would be  required  at start-up
               to  achieve  ignition in all cans.   However,  the  control  method  could be
               applied  immediately after  ignition.

                                          Water  Injection
                        Water injection  is  used  in many  turbine engines to allow
               engine power output to be  increased  without  increasing  turbine  inlet
               temperatures.   Use  of the  method  in  civil  aircraft  generally is.  limited
               to  take-off operations on  hot days.  No  data have been  published  on the
               effect of existing  water injection systems  on exhaust emissions  from
               aircraft engines.  However, steam  injection has been  shown  to  result  in
               substantial reductions  in  NOx emissions  (Ref  14).   With current  aircraft
               injection  systems,  water is  introduced well upstream  of the  combustor
               and probably  is vaporized  before entering  the combustion zone.   Therefore,
               its effect  can be expected to be the same  as steam  injection.

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                                                                      28
           It  is  assumed  that water  injection for NOx control would be
 accomplished  by  means  of injection  systems  similar  to  those  in  current
 use-   Water  injection  would be  used  during  take-off and climb-out opera-
 tions  with an injection  rate approximately  equal to the engine  fuel
 consumption  rate.   In  addition  to the  installation of  the  injection  system,
 the  aircraft  would  require a supply  of  demineralized water.   It  is possible
 that  regular  use of  water  injection  would reduce combustor service life
 due  to increased corrosion rates.
          Water  injection  is the only control method which has  been
 defined which would  achieve substantial  reductions  in  NOx emissions
 from existing engines.   It offers the potential advantage of discretionary
 usage.  That  is,  use of  the method  could be limited to situations where
 NOx  control  is required  to improve  local air quality.

                     Modify Compressor Air Bleed Rate
          This control method  consists  of  increasing the bleed  air rate
 from  the  compressor  during low  power operation.   Its effect  would  be to
 reduce the flow  of  air through  the  combustion chamber  and  increase the
 fuel-air  ratio.   As  with control method tk  (divided fuel supply),  this
 change would  produce more  efficient  combustor operation and  reduced  CO and
 THC  emissions.  Maximum  air bleed rates for current engines  are approxi-
 mately 5  to  10 per  cent  of total airflow.   In defining this  control
 method,  it  is assumed  that this rate can be increased  to 20  per cent at
. id.le  by modification of  the flow passages and bleed valves at  the  compressor
 exit.  These  modifications must be  achieved within  the geometric constraints
 of  the engine cowling,  and bleed air must be exhausted without  creating
 excessive noise.  With these constraints, a bleed  rate of  20 per cent
 may  not be feasible.  However,  some increase over  current  rates is  likely.

                  Variable-Geometry  Combustion Chamber
           Variable  geometry  in  combustor design  is. not a new concept.
 This  feature  has been  employed  in experimental  combustors  for many
 years  (Ref  15).   It  has  not been used  in practice  since the  added
 complexity has not  been  justifiable on  the  basis of  improved combustor

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                                                                      29
performance.  The function of variable geometry is to provide control
of the fraction of the total flow which enters the combustion zone.
With such control, the combustion zone fueliair ratio can be maintained
at a value corresponding to efficient combustion performance at all
operating conditions.   This feature alone will provide substantial
reductions of CO and THC emissions at low power.   With the addition  of
an advanced type of fuel injection system which provides a high degree
of premixing of fuel and air, substantial reductions of NOx and particulate
emissions also can be achieved (Ref 16).
          A variable-geometry combustor increases the complexity of  the
engine and its control system, and therefore, would increase the cost  of
developing and manufacturing the engine.   It  is possible that a combustor
with movable parts also will have a shorter service life than fixed
geometry combustors.

                      Staged  Injection Combustor
          Staged  injection  is a concept wherein combustion occurs in
discrete steps in the flow of air through the combustion chamber.  The
concept can take a variety of forms.  However, the most likely form for
improved emission control would consist of dual combustion zones arranged
in series with independent fuel injection in each zone.  The first zone
would serve primarily as a pilot combustor and would operate continuously
at a fuel-air ratio providing very efficient combustion.  The rate of
fuel injection in'the second zone would vary widely to provide variation
of engine power.  Fuel would be introduced by means of advanced fuel.
injection concepts which provide a high degree of premixing with the
inlet ai r.
          The added flexibility of dual combustion zones and fuel
injection systems would be used to achieve the same results as with
variable geometry.  Performance evaluations of staged  injection combustors
have not been published, but  it is reasonable to expect substantial
reductions  in all emissions with the use of this concept.  The approach
is advantageous  in  that no movable combustor  parts are required.  However*
a staged injection combustor may be larger in size than a conventional
combustor for the same engine.

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                                                                      30

                      Piston Engine Modifications

           Control methods considered feasible for aircraft piston engines
are  listed  in Table  11.  These methods  include most approaches to control
of carbon monoxide  (CO) and total hydrocarbon (THC) emissions which have
been developed for automotive engines.  Control methods for nitrogen
oxide  (NOx) emissions are not included  since the fuel-rich operating.
conditions of aircraft piston engines automatically result in low NOx
emission rates (Ref  1).  NOx emission control may be  required, however,
in conjunction with any attempt to-reduce CO and THC emissions by changing
engine operating conditions.
           Eight piston .engine control methods are listed,  including
direct-flame afterburners and water  injection which are not being con-
sidered currently for automotive engines.  Afterburners are included
here since  they might be used to advantage by utilizing the high.velpcity
airflow around the aircraft.  Also,  the feasibility of adapting other
methods may be less  for aircraft than for automobiles.
          The piston engine emission control methods were  identified and
evaluated  through reviews of published  evaluations of these methods.  Of
the methods identified, all are considered applicable to existing engines
except for any attempt at redesign of the basic engine or  its control
systems.  The methods are described briefly below.  More detailed
descriptions of these methods can be found in References 17 and 18.

                         Simple Air  Injection
           Simple air injection consists of controlled amounts of air
injection at the exhaust ports of each  engine cylinder.  The method
results in modest reductions in CO and  THC emissions.

                           Thermal Reactors
          The thermal reactor is an extension of the  air injection concept.
An insulated chamber is mounted in the  exhaust system into which air is
injected.   Improved mixing of exhaust gases and air and increased residence
time provide substantial reductions  in  CO and THC emissions without

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                                                                      31
increasing NOx emissions.  Thermal reactors do not function effectively
until they reach their steady operating temperatures.   Thus, they are
not effective at reducing emissions during engine start-up.

                          Catalytic Reactors
          Catalytic reactors for control of CO and THC emissions function
in a manner similar to thermal reactors.  Additional air is injected and
mixed with exhaust gases in a chamber mounted in the exhaust system.
Oxidation of CO and THC  is induced by catalyst beds through which the
gases flow so that the reactor operates at a lower temperature than
thermal reactors.   Like  the thermal reactor, the catalytic reactor does
not function until it reaches its normal operating temperature.

                       Direct-Flame Afterburner
          A direct-flame afterburner is a thermal reactor with both air
and additional fuel injected to maintain the temperatures required for
CO and THC oxidation.  The use of additional fuel for temperature control
allows the afterburner to be installed at the end of the exhaust stack
where air could be induced from the propeller stream.   Air induced in
this manner would eliminate the necessity for an auxiliary air pump.
An afterburner would, however, require a separate fuel supply system.
          Afterburner effectiveness would be comparable to thermal reactor
performance and it would be effective immediately upon start-up.  Thus,
•its over-all performance would exceed that of the thermal reactor over
a complete operating cycle.

                            Water  Injection
          Water injection provides a means for operating an aircraft
piston engine at leaner  fuel-air ratios so that CO and THC emissions
would be reduced.   Water injection would allow this change without
increasing engine heating or NOx emissions.  The function which would be
served by water injection is now provided by the injection of excess fuel.
The rich fuel-air ratios resulting from this practice are responsible for

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                                                                       32

 the  high  CO  and  THC  emission  rates  from  aircraft  piston engines
 (Refs  1 and  3).
           With  this  control method,  water would be  injected  at controlled
•rates  into the  engine  inlet manifold.  A separate fluid storage  and
 control system would be  required  as  well as  a  supply  of demineralized
 water.  The  regular  use  of water  injection could  be expected  to  result
 in  increased corrosion rates  of engine components.

                     Positive  Crankcase Ventilation
           Positive crankcase  ventialtion (PCV)  is in  nearly  universal
 use  in  new automobile engines.   It  consists  of a  connecting  line between
 the  engine crankcase and the  air  intake  with a valve  to control  the  flow
 rate in the  line.  The system creates a  flow of air through  the  crankcase
 which  flushes blow-by gases from  the cylinders and carries them  into the
 air  intake.   CO  and  THC  emissions in the blow-by  gases are oxidized
 during  the normal cylinder combustion process  or  by an auxiliary
 control method  in the exhaust system.
           PCV systems would not be  effective with aircraft engines unless
 they were adjusted to operate at  leaner  fuel-air  ratios.  With their
 present operating conditions, no  excess  oxygen  is available  in the engine
 cylinder  to  oxidize  blow-by emissions.   Thus,  the PCV system  is  not
 considered to be an  effective emission control method for aircraft piston
 engines unless  it is combined with  another method for CO and  THC
 emission  control.. When  combined  with.another  control method  such as a
 therma.l reactor, PCV will  increase  the effectiveness  of THC  emission
 control substantially since the other control methods do not  affect
 blow-by emissions.

                     Evaporative  Emission Controls
           Control systems are being developed  currently to reduce THC
 emissions due to evaporation  from fuel supply  systems.  These control
 systems make use of  a variety of  concepts and  components, but generally
 accomplish emission  control by collecting evaporated  fuel while  the  engine
 is shut down and feeding the  collected fuel  to  the engine when  it is started.

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                                                                      33

The magnitude of evaporative emissions from piston-engine aircraft is
not known, and the adaptability of automotive control methods to aircraft
also is unknown.  It can only be stated qualitatively that THC emissions
probably occur due to evaporation and that they are amenable to some
degree of control by methods which exist for automobiles.

                            Engine Redesign
          During the past several years, several minor design changes
have been made with automobile engines to reduce emission rates without
the addition of auxiliary control devices.  These changes include
modifications in combustion chamber geometry, valve and spark timing,
and fuel-air ratios.  Other changes which might also be made to reduce
emissions include changes in compression ratio and cylinder wall tem-
peratures.  Some degree of emission control can be achieved by such
changes in aircraft piston engines.  However, these changes also are
likely to increase engine operating temperature, reduce power output, and
increase NOx emissions.  Thus, the degree of CO and THC emission control
attainable by engine redesign is considered to be modest, unless other
control methods are used in conjunction with design changes.

                          Fuel Modifications
          Modifications of aircraft fuels can be considered for control
of emissions of lead, SO., and visible smoke.  These modifications
consist of removal of fuel impuritiesj the reduction of currently used
additives, or the introduction of new additives.  It is recognized that
emissions of reactive hydrocarbons and aldehydes are related to fuel
composition.  However, these relationships are not sufficiently well
defined to provide bases for emission control methods.
          Fuel modifications are discussed briefly below, but have not
been considered in the detailed analyses of emi.ssion control effectiveness
and costs which follow.  With the exception of lead emission control,
modifications of fuels are1 .not considered to be feasible methods of
emission control.  The effects and costs of lead reduction are well-
documented elsewhere and need not be evaluated in detail in this program.

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                         Lead Emission Control
          Lead additives are contained only in aviation gasolines used
by aircraft piston engines.  Turbine engine.fuels do not contain lead
additives.  Low-lead or lead-free gasolines similar to those which are
available for automobile engines in limited quantities, could be used
in aircraft engines.  However,, a higher lead content may be required for
aircraft engines because of the relatively high octane requirements of
certain engines.  Low-lead gasolines are more costly than conventional
leaded gasolines by about 10 per cent.  A more serious problem, however,
is the incidence of valve failure resulting from the use of low-lead
gasoline.  Thus, a reduction in lead may result in increased engine
maintenance costs as well as fuel costs.  The degree of emission control
achievable is, of course, directly proportional to the reduction in lead
content of the fuel.

                         S02 Emission Control
          Both aircraft piston-engine and turbine-engine fuels contain
sulfur as an  impurity.  The sulfur content  is highest  in the heavier
turbine engine fuels. -However, the sulfur content of all aviation fuels,
typically less than 0.05 per cent, is far below that of liquid petroleum
fuels used for heat or power generation in stationary combustion systems.
Reduction of  the sulfur, content of aviation fuels below their current
levels would be very costly.

                        Smoke Emission Control
          Various materials have been found to reduce smoke emission from
turbine engines when added to fuels in small quantities (Ref 1).  Most
of these materials are metal compounds which have adverse effects on
engine components and produce new emission species with unknown, but
unattractive, characteristics.  Thus, additives for smoke control are
not considered to be desirable for regular use in aircraft engines at
the present time.   It is possible, however, that further research will
produce smoke-control additives which are free of these undesirable
effects.

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                                                                       35
 Control  Method  Effectiveness
           The  effectiveness  of  each  of  the  control methods  listed  in
 Tables  10  and  11  has  been  estimated  and  the-results  are  listed  in  Tables
 12 and  14.   Estimates are  based upon demonstrated performance  in a few
 cases.   However,  in most  instances,  no  direct  experience  has been
 obtained with  these control methods  on aircraft engines.  Therefore,  to
 a  large extent, the effectiveness estimates are based on  theoretical
 analyses of engine performance with  the changes in operating conditions
 associated with the control methods.  The bases for  these estimates are
 indicated  in the tables.
          Effectiveness of each control method has been rated according
 to a scale of  the degree of emission  reduction attainable.  The degree of
 reduction  is expressed on an "order  of magnitude" basis where,  in  this
 case, an order of magnitude  is defined as a reduction by a factor  of  two.
 Considering the uncertainties involved  in the application of these control
methods to aircraft engines, effectiveness estimates cannot be made more
 accurately than within a factor of two.  Therefore,   this approach  is
 considered to  be valid and it offers  a systematic method of classifying
 the effectiveness of  various engine  and control method combinations.
The effectiveness rating scale  resulting from this approach is as  follows:
       Order of        Per Cent Reduction     Fraction of Emission
     Affect iveness         Attai nable            Rate Remaining
        First             50                          0.5
        Second            75                          0.25
        Third             90 (Rounded)                0.1
 Emission control effectiveness  is indicated in the tables by one of these
 orders of effectiveness for each control method and  pollutant for  which
 a.  significant  degree  of control would be expected.   Pollutants for which
 little or no control  would be expected are not listed.  Effectiveness is
 indicated separately  for each engine  class.
          No estimates have been made for control  of reactive hydrocarbons
or aldehydes since control  methods applicable to these emissions have not
been identified.  It  is reasonable to expect some reductions in these
emissions along with  reductions in THC emissions.

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                                                                       36
          Emission control effectiveness for turbine engines is based
upon reductions attainable from "best current" emission rates.   These
rates are defined as those attainable through control method tl-- minor
combustor redesign.   The best current rates were taken from the compilation
of emission data shown in Figures 1  through k.   It is assumed that all
engines in each class could be modified to achieve these best rates.   The
values  of  these  rates  are listed  in  Table  12A.  These  best  rates  are
not  the lowest  rates  indicated for each engine  class,  but are  rates near
the  low end of each  data  set which appear  to be realistically  attainable.
The  use of the "best  rate" basis  is  necessary to  allow effectiveness esti-
mates  to be made  by  engine class.  Because  of the wide variations  in
actual  emission  rates  for turbine engines,  the  use of  average  rates as
a basis for an effectiveness analysis would be  less  meaningful.
           Effectiveness estimates for piston engines are based on  reduc-
tions  from current uncontrolled  rates  listed  in Table  13«   Emission rates
from piston engines  do not vary widely, so  that control effectiveness
can  be  based on  average rates for existing  engines.
          The effectiveness estimates shown in  Tables  12 and ]k  are based
in most cases on  the  application of  individual  control  methods with the
engine  otherwise  unchanged.  Exceptions are made  in  the case of  methods
t2,  tk, t5, and  t6 for which  it  is assumed  that method tl has  already
been utilized to  achieve  "best current emission rates".  Method  p6
(PCV)  also is an  exception  in that  it  is only considered to be useful  in
combination with  method pi, p2, p3,  P^, or  p5«
           From  the effectiveness estimates,  the following general  state-
ments  can  be made with regard to  the various emissions:
           1.  Minor  combustor modifications (tl)  would result  in modest
              reductions  in all emissions,  and  would eliminate all or
              most visible  smoke emission.
           2.  Other  turbine engine modifications  would provide further
              reductions  in particulates  (t2),  NOx  (t$), and low power
              emissions of  CO and THC  (tk  and t6).
           3.  Future turbine engines with  combustors of advanced design
              will have  low  rates of emission for all  pollutant  classes
              and probably will  not  require additional control methods.

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                                                                      37
          k.  Various degrees of control of CO and THC emissions can
              be achieved for aircraft piston engines by modifying
              engine design characteristics, or by installing auxiliary
              control devices.
          Any of the modifications defined for existing turbine engines
(tl through t6) could be combined to achieve increased emission control
effectiveness, with the exception of methods tk and t6.  These two methods
are mutually exclusive.  Piston engine modifications pi through p5
are designed to serve the same function and, thus, are mutually exclusive.
All of the others could be combined with any of pi through p5 to achieve
increased emission control effectiveness.

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                                                                      38
                IMPLEMENTATION COSTS AND TIMES OF CONTROL
                     METHODS:  ENGINE MOD IFI CAT IONS
          Included among the objectives of this program is an evaluation
of the cost and time requirements associated with the application of
emission control methods to aircraft engines.  The program is concerned
with engines in current use and engines which will be in service during
the next 10 years.  The evaluation of current engines is based upon the
application of control  techniques to specific existing engines, whereas
the evaluation of future engines is on a different basis,  involving future
engine characteristics  and populations.  The purpose of this section is
to present the results  of the analysis in terms of cost and time require-
ments associated with the application of several specific  emission control
methods.

Engine Classification and Control Method Definition
          The current turbine and piston engine population, classified into
three turbine classes and one piston class, was presented  previously in
Tables 7 and 8, respectively.  These tables  list engines by "family",
meaning that only the basic engine model number is considered, such as CF6
or JT9D.  The table also identifies the engine manufacturer, the engine
type, the engine thrust or equivalent power  level, the turbine engine
combustor type, the number of engines  in current use, the maximum produc-
t.ion capacity for each engine, where available, and the aircraft class in
which the engine  is used for correlation with the data provided in Tables
1 through 5-  Note that the total number of  turbine and piston engines listed
in Tables 7 and 8 in current use are further broken down into air carrier,
general aviation and military engines.
          The emission control methods applicable to both turbine and piston
engines are listed in Tables 10 and 11, respectively.  In each table, the
control methods are subdivided  into categories applicable to current engine
(retrofitting) and to future engines.  In general, it has  been concluded
that emission control methods appropriate for future engines cannot be
incorporated into current engines.  Since the incorporation of these

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                                                                      39
"future" engine emission control methods would be an intrinsic part of the
"future" engine design process, the analysis of the cost and time involved
is not compatible with the analysis conducted on current engines.  Hence,
future engine emission control  is discussed separately in this section,
following the initial discussion of the current engine analysis.

Cost and Time Analysis Procedures
          An analysis of the cost and time involved in the application of
various emission control methods to current engines was conducted, using
the procedures applied to the JT8D engine "family" in Reference 2, as a
basis.  Costs and times were established for both turbine and piston
engines for two general categories, which are best described as "Develop-
ment" and "Implementation" costs and times, the elements of which are
described in detail below.
          For the case of the turbine engines, it should be recalled that
three classes of engines has been suggested in Table 7, based upon thrust
level ranges.  For each class or thrust range, a typical  or "baseline" engine
was selected for the cost analysis, with the selection criteria being
generally based upon population.  The analysis procedure is illustrated
in the tables provided which include a "sample calcuation" of both the
development and implementation costs and time for class T2 engines for
which the JT8D is the "baseline" engine.  A similar procedure is  followed
with sample calculations provided, for the piston engines, although no
specific "baseline" engine was  identified, since only one class of engine
exists and the size or power range is much narrower for the piston engines
as compared to the turbine engines.
          The turbine and piston engine sample calculations are  described
in the following paragraphs.  It should be noted that the explanatory
paragraphs apply generally to one engine class only such as the class T2
turbines for which the JT8D is used as a baseline engine.  In order- to
arrive at costs for other turbine engine classes, a scaling factor is used
which is explained in later paragraphs.   The process can be visualized best
by a study of Figures 6 through 10.

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"Development" Cost and Time Analysis
          The term "Development", as used herein implies the "one-time"
costs and times associated with the evaluation and refinement by testing
of a given emission control method for a specific engine family.  It also
includes the tool design and procurement costs and times required to in-
troduce the given control method into the production schedule for pro-
duction engines, if applicable, and with the overhaul schedule for retro-
fitted engines.  The "development" cost and time elements which were treated
for each control method are described below, in the order listed in Tables
15 and 17-

                      Engineering Development Cp^t
          This cost consists of the manpower costs associated with a "team"
of engineers and draftsmen who perform the necessary analysis and design
calculations required for a given control method and produce sets of draw-
ings and test hardware ready for testing.

                      Engineering Development Time
          This time covers the period from the initial analysis until hard-
ware is ready for testing.

                             • Testing Cost
          This cqst consists of the manpower costs associated with a "team"
of engineers and technicians who perform the tasks of assembly, installation,
testing, data analysis, and disassembly  in that order on various sets of
test hardware supplied in original and modified form until the testing of
the final, refined emission control system is completed.  Testing facilities
are assumed to exist.  The cost of operating the test facilities is included.

                              Testing Time
          This time covers the period from the receipt of initial hardware
ready for test through the analysis of the test results of the final, re-
fined emissions control system.

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                             Tool  Design Cost
          This cost consists of the manpower costs  associated  with a  team
of engineers and draftsmen who produce a set of drawings,  including tooling,
required to fabricate a complete emission control  system.

                             Tool  Desi qn Time
          This time covers the period from completion of  final testing until
completion of final drawings, ready for production.

                          Tool Procurement Cost
          This cost assumes special tooling and/or  equipment  is  required
in order for the given emission control method to  be produced  at a rate
equal to that required.  It is recognized that the  production  rate and
resulting cost depends upon the number of engines  in use  and  the current
or projected engine production rate.

                          Tool Procurement Time
          This time covers the period from the completion of  final
drawings until all tooling and/or equipment required is available for
initiation of production of the specific engine control system components.

                         Total Development Cost
          This cost is initially found as the cost  per engine  family (JT8D)
and is the summation of all the cost elements previously  listed, including
engineering development, testing,  tooling design,  and tooling  procurement.
Total development costs per engine family were assumed to vary among the
several emission control methods considered, but were assumed  to be equal
for a given control method applied to various engine families  in the same
engine class.  The number of engine families in a  given class  is used to
get the final development cost for that class.  It  is recognized that the
cost of the test hardware and test facility operating costs will vary with
engine size (or class) but  differences  are assumed negligible  for  the analysis,

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                         Total Development Time
          This time is the summation of all the time elements previously
1 isted, as above.
          Total development times were assumed to vary among the several
emission control methods considered, but were assumed to be equal  for a
given control method applied to various engine families in the same engine
class and also in different engine classes.
          A summary of these costs and times for both turbine and  piston
engines is presented in Tables 15 through 18 for the various appropriate
emission control methods.

Implementation (Retrofitting)  Cost and Time Analysis
          The term "implementation cost" as used herein applies to those
cost elements involved in the incorporation of a developed control system
into a specific engine which is currently "in-use".   This implies  a retrofit
operation.  The cost can be expressed as a total cost per engine or as
a total cost when multiplied by the total number of  engines affected.  The
latter value is assumed to be the total implementation cost, unless other-
wise specified.  The implementation analysis assumes that control  systems
will be incorporated on an "overhaul" basis, as defined in Reference 2, and
two and one-half years is assumed for an "implementation time" for the
JT8D, used as a baseline engine in the sample calculation.
          The "implementation" cost and time elements which were treated
for each control method are described-below.  As with the development costs
and time calculations, the procedures for calculating implementation costs
and times are illustrated by means of tables which contain sample  calcula-
tions for the same class T2 engines for which the JT8D is still the "base-
line" engine.  The sample calculations are found in  Tables 19 through 22
and again show results for only the one class of T2  engines.  The  scaling
factor previously mentioned and explained later is used to obtain  costs
for other engine classes, where applicable.  Since there is only one piston
engine class, no scaling relationship is required for piston engines.  Again,
a study of Figures 6 through 10 should clarify the procedures used.

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                    Lost Service Life Cost Per Engine

          Since "implementation" was assumed to be on an overhaul basis,
as defined in Reference 2, the cost of replacement would include the cost
associated with the remaining service life of the original  combustors.
On the average, the unused service life was assumed to be 2500 hours for
the JT8D, or one-fourth the total combustor life.  The corresponding
cost would be one-fourth of the original cost of the combustors or
approximately $2500 per engine in the sample case of the JT80.

               Initial Additional Installation Cost Per Engine

          This cost includes the additional manpower and equipment costs,
if any, per engine involved in the installation of a given  emission control
system into a specific engine.  For example, it was estimated that the
cost of installing a "minor" combustion chamber modification (control
method t.) into a JT8D engine would be $2000, per Reference 2.

             Continuing Additional Cost Per Engine Per Year
          This cost is associated with the increased cost of combustion
system components and their (probable) reduced service life.  As an
example, this cost for a "minor" combustion chamber modification on the
JT8D engine was calculated to be $2500 per engine per year  , assuming
a service life of. 5000 hours or two years of service reduced from the
current assumed combustor service life of  10,000 hours or k years of
service.  The increased list price of the combustion chamber components
was estimated to be $11,000 compared to a current approximate price of
$10,500.  Actual  prices vary as a function of the quantity  of the combustors
ordered  by an operator and also as a function of the annual inflationary
  Assuming that on the average, aircraft operators pay 8? per cent of list
  price, increased yearly cost is
                              new cost/set _ old cost/set
          cost/engine = 0.8?  service life   service life
                              $11.000 _ $10.500
                      = 0.87  2 years   k years   = $2500 per year

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                                                                      kk

spiral, neither of which effects has been specifically included in this
analysis.  The assumed reduction in service life for modified combustors
is consistent with the conclusions of Reference 2, based on aircraft
operators experience.  Although modified combustor service life has not
been established yet, even for the JT8D, it seems reasonable that any
modifications to a highly developed component such as the combustor will
introduce some initial difficulties, the end result of which is a
reduction in service  life or a loss in reliability.  The solution to the
problem is another phase of development, not included elsewhere in this
analysis.  The validity of the assumed values for reduced service life
is unknown at this time but the need to include this cost element in the
analysis certainly seems valid.

                  Total Implementation Cost Per Engine
          This cost  is the summation of the three previously listed
cost elements.  Note  that the units of the "continuing additional cost
per engine per year"  requires that some time span must be introduced
in order that the units be consistent with the other cost elements and
the resulting summation legitimate.  Since the period of interest for
this program has been stated to be the 10 year span from 1970 to 1980,
10 years has been assumed for a time span, henceforth referred to as
"engine life".  This  10 year span has no necessary relationship to the
actual useful life of either turbine or piston engines.  A cost/time
model was established for purposes of consistency, as shown in Figure 5,
which assumes a finite engine life as explained above and a time
between overhauls (TBO).  In the sample baseline case of the JT8D engine,
5000 hours or 2 1/2 years was assumed for the time between overhauls
(TBO) and an engine  life of 10 years was also assumed.  This results
in a total implementation cost per engine of $35,500 for the 10 year assumed
life of the engine.   Similar assumptions were made for the piston engine
analysis, as shown in Figure 5-

                        Total Implementation Cost
          This total cost is established from the previously described
implementation cost per engine by multiplying that unit cost by the number

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 of engines  in the given class of turbine engines.  The number of turbine
 Class T2 engines is projected to be 35,87*+ which means that the total
 implementation cost will be 35,87^ x $35,500 per engine or 1275 million
 dollars for that class of engines for the assumed 10 year engine life
 and 2 1/2 year assumed value for TBO.  Sample calculations of total
 implementations costs for both turbine and piston engines are provided
 in Tables 19 and 21.

                        Total Implementation Time
           As previously stated, implementation was assumed to be on an
 overhaul basis which  results in an average value of two and one-half years
 to completely convert all engines in a given fam.i ly of turbine engines in
 use.
           A summary of the implementation costs and times for bn«-h
 turbine and piston engines is presented in Tables 19 through 21 for
 the various appropriate emission control methods.  The principal guidance
 for distributing costs and times among the various emission control methods,
 relative to the .initial t. case presented here and in Reference 2 for the
 JT80, was obtained in References 20 through 2**.

Total  Development and Implementation Cost and Time Analysis
           Having established the costs and times associated with the sample
 case  of the JT8D engine, and the T2 engine class, of which it is a member,
 the analysis procedure used to obtain'cost and time data for the entire
 aircraft engine population is illustrated graphically in Figure 6.   It can
 be seen from Table 7  that the JT8D is a Class T2 turbine engine and that
 there are 20 engine "families" in that class which also includes a total
 number of 35,87^ engines.   Assuming that the JT8D engine family is
 representative of all engine families in the Class T2 turbine group, total
 Class T2 turbine engine development costs are obtained by multiplying the
 JT80  baseline development cost by 20 as in Table 15 and the total  Class
 T2 turbine engine impelmentation cost is obtained by multiplying the JT8D
 baseline total  impelmentation cost per engine by 35,87*1,  as in Table 19-
 It is assumed that  both development and implementation times  as a function

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of emission control methods for the JT8D engine are equal for all other
engine families in the T2 class and in the other turbine classes.  Similar
assumptions are made for the piston engine families, as tabulated in
Table 8.
          Extending the results of the JT8D baseline case to all "families"
in the Class T2 turbine group results in a simple table, as illustrated in
Figure 6, of total cost and total  time for all Class T2 turbine engines,
for each emission control method,  covering the period from initial engineering
development through the conversion of the last engine "currently" in use
at the end of the overhaul period assumed.

                           Cost Scaling Factor
          Using the analysis described above, a table of total costs and
total times for one class (T2) of turbine engines has been explained.  To
arrive at comparable tables for other classes of engines, as suggested in
Figure 6, it is necessary to repeat the analysis for other "baseline"
engine families in the other engine classes or to establish a scaling re-
lationship which can be used to obtain tables of costs and times for the
other engine classes.  The latter approach has been selected.

                       Technical Scaling Parameter
          Considerable effort has been devoted to trying to correlate
aircraft turbine engine cost with technology, which includes both size
and performance. -An example of this effort is provided in Reference 25.
Since both size and performance are involved  in the turbine engine clas-
sification system adopted in this analysis, the combination technical
parameter presented in Reference 25 seemed appropriate and in fact provides
a' reasonable scaling relation as shown in Table 23 and Figure 11.

                         Final Scaling Parameter
          A cost variation proportional to the square root of engine
thrust (or equivalent horsepower)  was suggested and investigated with
results also shown in Table 23 and Figure 11.  The simplicity of this
scaling parameter is appealing and since it appears to correlate very
well with the technical scaling parameter, its use was adopted for this analysis

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                          Final Scaling Factor
          As suggested in Figure 6, simple tables of costs and times are
required for all three turbine engine classes, of which only the Class T2
engines have been explained, using the JT8D engine as a baseline example.
Baseline engines for the other two turbine classes were selected for
scaling purposes, based generally on population, as shown in Table 7 and
1 is ted below:
                    Turbine Class     Baseli ne Enqi ne
                         Tl                T53
                         T2                JT80
                         T3                TF39
Calculation of both the technical and final scaling parameters and normali-
zation of the parameters relative to the JT8D baseline engine case,  yields
normalized final scaling factors as shown in Table 23.  The scaling
factors used were 0.35, 1.00, and 1.6*+ for the Class Tl, T2, and T3
turbine engine classes, respectively.  These factors are applied to  the
total implementation cost per engine only, based on the assumption that
development costs are essentially independent of turbine engine class.
Again, reference to Figures 6 through 10 should aid in understanding the
procedures used.
Final Cost and Time Results for Current Engines in Service
          The final results of this analysis are presented in Tables 2*+ through
27 for both turbine and piston engines- now in service.  The tabulation includes
the engine classification, the baseline engine assumed, the emission control
method, the number of engine families in a given.engine class, the number
of total engines in a given engine class, the total development and  imple-
mentation cost for a given engine class, and the total development and
implementation time for a given engine class.  The latter two values of
total cost and total time are presented for engine classes as a function
of the several control methods selected.  Costs are further broken down
to show air carrier, general aviation, civil  aviation and military aviation
costs in addition to total costs for both turbine and piston engines.   The
result of Tables 2k and 25 are shown graphically in Figures 6 through 10.

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Total Implementation Cost/Enqine^. for "Production" Engines
          The analysis and results presented thus far,  for both turbine and
piston engines, apply to engine models and populations   now in existence
and assume  emission controls will be developed and implemented on an
overhaul basis, as previously explained.   Certain of these engines will
still be in production at the end of the  development period and the
"implementation" costs associated with production engines must be
treated differently from engines currently in service and requiring
a retrofit of the developed control systems.   Implementation costs were
analyzed for production engines on a basis similar to that presented
previously.  However, the cost associated with the useful life remaining
in a discarded combustor system cannot be included and  it is assumed
that the additional installation cost, if any exists, associated with the
new emission control system will certainly be lower than that for a
retrofitted engine now in service.  The continuing additional cost per
engine per year was assumed to be the same as for a retrofitted engine and
10 years was again used as a value for "engine life" in order to have the
cost results on  a comparable basis.  Since future engine production
values are unknown, results are presented on the basis  of a 10 year imple-
mentation cost per engine.  A "sample calculation" for  both turbine and
piston engines is presented in Tables 28  and 29, respectively.  These
resul.ts can be compared with those presented in tables  19 and 21 and are
somewhat lower, which seems reasonable.  Final results  for all classes of
engines, including the three turbine classes, is presented in Table 30-
As indicated, the same scaling factors previously presented have been
used for the turbine engine classes.

Control Methods Applicable to Future Engines
           Intensified interest in controlling emissions from aircraft turbine
engi.nes has already stimulated research on combustors for the next engine
generation.  Current combustor design practices are recognized to offer
only limited emission reduction.   In late 1968, the National Academy of
Engineering recommended government support for the development of com-
bustors using variable geometry and air atomization fuel injectors (Ref 29).

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The advantage lies in controlling local combustion zone fuel-air ratios
over the entire operating range.  This departure from current design practice
does not represent a new concept, but rather a method for achieving low
emissions from the current design concept.
          A more radical suggestion for reducing emissions in the next
generation of engines is a new design concept - viz,  the use of staged-
combustion (Ref 16).   The idea is to introduce a series of separate com-
bustion zones with independently controlled fuel injection in each zone.
Air atomization fuel  injection would be used in all zones.  Again the
objective is to maintain control of local  fuel-air ratios over a wide
operating range of the combustor.  Several fluid dynamic and combustion
problems must be solved before staged-combust ion becomes workable.  The
only serious development problems in the case of variable geometry center
on the added mechanical and control system complexity.
          Reduced emissions is not the only factor.promoting development
of more complicated combustors for the next engine generation.  Better control
of the mixture can also provide more uniform turbine inlet temperature
profiles.  As turbine inlet temperatures  increase with the next generation;
more uniform profiles over the entire flight map may be a definite require-
ment for practical thermomechanical design of cooled turbines.  The
feasibility of advanced combustors for reduced emissions should be assessed
with th i s in mi nd.

                  Basis for the Cost and Time Estimates
          Either of the control methods applicable to future engines will
require development of new combustors.  In the past, the development of ad-
vanced component design concepts has to a large extent been supported by
the federal government - by NASA or by the military.   Indeed, the USAF
ATEGG type program might be ideal for developing variable geometry or staged-
injection combustors.  Even after the technology is established, however,
each new engine requires separate additional development of its components.
The total development cost for an advanced combustor is thus a somewhat
misleading figure when assessing the practicality of emission control
methods.  New combustors will  be developed regardless of emission requirements,

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                                                                      50
The number of interest is rather the incremental  cost which will  result
if emission criteria necessitate variable geometry or staged-combustion.
The cost and time for developing demonstrator combustors using variable
geometry or staged-combustion are estimated below.   Also estimated are
the fractions of the total cost and time which will result from emissions
control rather than from normal evolution of advanced combustors  for new
engines.  The development costs and times are broken down into design
and testing categories in the same manner as in the preceding treatment
of control methods for current engines.  An additional category,  per-
taining to incorporation of prototype combustors  into engines covers
the effort required to integrate the combustor with other components.
          There is a second approach to assessing the cost of emission
control in future engines - viz, the incremental  increase in engine
purchase price which results from more complicated combustors. Hardware
and assembly costs will increase with added design complexity.  Total
engine costs vary radically with parameters unrelated to combustion (e.g.,
airflow and weight).  For this reason, the incremental costs of emission
control in future engines are best defined in terms of the percentage
of the total engine cost associated with the combustor.   In the JT8D the
combustor represents roughly U.5 per cent of the  engine cost (from Ref 2,
assuming 11K for the combustor and 250K for the engine).  The combustor
costs as a per cent of the engine price are included in Table 31, both
for variable geometry and for staged-combustion.
         ,ln sum, then, three cost numbers are provided:  advanced proto-
type combustor development cost; fraction of development cost associated
with emission control; and fraction of engine purchase price associated
with different combustor concepts.  All raw cost  numbers assume an engine
size essentially the same as the JT80.

                          Discussion of Results
          The various cost and time numbers for conventional combustors,
for combustors incorporating variable geometry, and for staged-injection
combustors are summarized in Table 31«   The discussion below examines the

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advantages and disadvantages of each emission control  method for future
eng i nes.

                       Variable Geometry Combustors
          Since variable geometry combustors using air atomization fuel
injectors were recommended in 1968 by the National Academy of Engineering,
it seems  safe to assume that development efforts are already underway.
Air atomization fuel injectors are not expected to cost more than con-
ventional injectors once production levels are reached (Ref 30).   The
major cost lies rather in the added mechanical complexity of a combustor
with hot  moving parts and in the need for an actuation and control system
to vary the geometry during engine operation.  Any gains in engine per-
formance  or in turbine weight (as a result of better inlet temperature
profile)  will at least be offset by the additional weight of the variable
geometry  combustor.  The incremental cost and time associated with
introducing this type of combustor in future engines consists primarily
of the development and manufacturing problem of varying the geometry.
          As indicated in Table 31, the design effort  required by
variable  geometry  is estimated to be twice that of a fixed geometry com-
bustor.  This figure assumes a 20 per cent increase in fluid design effort,
a 100 per cent increase in mechanical design, and a control design effort
comparable to the customary mechanical design effort.   The increased
cost of prototype  hardware represents first, higher tolerances on critical
varying geometry parts and second, additional actuation and control
components.  The increased test costs result first from time spent
optimizing the geometry at various operating conditions and second from
anticipated mechanical problems in actuating geometry  changes during opera-
tion.  The additional engineering effort required to incorporate a pro-
totype variable geometry combustor into an engine results from added control
system complexity.
          The purchase cost of a variable geometry combustor using air
atomization fuel injectors is expected to be about twice that of a comparable
fixed geometry combustor.   The combustor hardware cost should increase  by
50 per cent, and the rest of the additional cost stems from the actuation
and control hardware.

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                                                                      52

          Since no new combustion concepts are involved with the variable
geometry combustor, the essential engineering problem is to design an
actuation and control system which is compatible with the rest of the
engine.  The only other issue is assuming adequate life of more critically
designed parts.  The development time estimated for a prototype combustor
of this type reflects these considerations.

                       Staged-Injection Combustors
          Staged-combustion is a more radical departure from current com-
bustor design practice.  The problem with variable geometry is to implement
a concept which will surely work from a combustor performance standpoint.
The problem with staged-injection is to develop and to prove the concept
itself.  Several combustor performance difficulties are anticipated.  These
are best understood by describing the concept in slightly more detail.
          One approach to staged-injection uses two air atomization injec-
^ors where one  is used now.  One of these fuels a pilot burner, and the
other  introduces the major part of the design fuel flow into a prechamber.
Fuel is premixed and vaporized in this prechamber before entering the
combustor proper.  A serious technical problem is the danger of flash-back
into the prechamber.  High gas velocities are needed in the prechamber for
mixing, and a considerable pressure drop is needed between the prechamber
and combustor proper to prevent flash-back.  Careful fluid dynamic design
of a more complicated network is needed if pressure losses are to be
acceptable.  On the other hand,   the flexibility provided by a pair of
injectors should improve combustor flame stability.
          The costs shown in Table 31 for the staged-injection combustor
reflect the need for technological development of the concept.  The much
larger engineering design and test effort indicated will be devoted to com-
bustor rig exploratory development programs.   Different arrangements of
the prechamber and pilot will require examination with particular attention
to a fluid dynamic design which will provide adequate prechamber mi-xing,
low pressure losses, and no flash-back problems.  Once an acceptable pro-
totype staged-injection combustor is obtained, it can more readily and
less expensively be incorporated into an engine as compared to the variable
geometry combustor.  No actuation or complicated control system is needed -

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                                                                     53

only two fuel lines with separate controls of the type currently used in
zoned afterburners.  Compressor diffuser designs will, however,  doubtlessly
requ i re revis ion.
          The production cost of staged-combustion is greater than that of
conventional designs first,  because twice as many fuel injectors are needed
and second, because the structural design must provide a more complicated
flow.path.   However, staged-combustion,  once developed,  should offer a
noticeable cost savings versus variable  geometry.

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                   EFFECTIVENESS OF CONTROL METHODS:
                    GROUND OPERATIONS MODIFICATIONS
Introduction
          This section of the report examines how effective seven sug-
gested ground operations changes would be in reducing aircraft emissions.
The next section will evaluate the cost and time for implementing the
changes.  The suggested changes are:
          1.  Increase engine idle RPM.
          2.  Use a minimal number of engines for taxi  operations and
              increase the idle RPM of the engines used.
          3»  Minimize unnecessary engine time by a system for controlling
              engine start and gate departure.
          k.  Minimize taxi time by parking aircraft near runways and
              using auxiliary vehicles to transport passengers to and
              from the terminal.
          5.  Tow aircraft between runway areas and the terminal, thus
              eliminating the taxi mode of engine operation.
          6.  Provide ground-based auxiliary power supply in order to elimi-
              nate use of on-board auxiliary supply units while at the gate.
          7.  Provide auxiliary equipment for emptying fuel  drainage
              reservoirs.
The effectiveness of the various changes in reducing aircraft emissions has
been evaluated for a single representative airport, Los Angeles International
Airport.  Each of the seven changes is discussed separately below.

Control Method Effectiveness

                       Increase Engine Idle RPM
          Two categories of turbine engine emissions, carbon monoxide and
hydrocarbons, result from incomplete combustion.  This occurs primarily at
low engine power settings because the combustor is optimally configured
for full power operation.  By operating engines nearer the combustor de-
sign condition, the emission rates for CO and hydrocarbons will be reduced.

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                                                                     55
Aircraft braking power and brake wear ultimately constrain the extent
to which the  idle RPM can be  increased.  Brake overheating already oc-
curs occasional ly dur.ing ground operation.
          Essentially a doubling of engine power was assumed to get a
benchmark for  the effectiveness of a higher idle in reducing emissions.
Figure  12 approximates the relationship between power and fuel flow.
Although this  approximation cannot be extrapolated to zero power output,
.it suffices for estimating emission reduction with idle power setting
change.  Figures 13 and 14 give CO and hydrocarbon emission rates versus
engine  power  setting.  Figures 12 through \k thus supply sufficient in-
formation to  calculate the per cent emission reduction which results from
doubling the  power during aircraft idle.
          Table 32 summarizes the reduction in engine emissions which
results from  doubling idle power output.  The table also indicates the
uncontrolled  emission rates for each engine and the number of engines  in
each aircraft  class (as per Ref 6).  Although increasing the idle RPM  re-
duces emissions per unit mass of fuel, increased fuel flow can offset  the
improvement  (as in the case of hydrocarbons for Class 2 aircraft).  Thus
the full benefit of increased idle RPM will be realized only if not all
engines are  in use during ground operations.

                    Uj>e Minimal Number of Engines
                        at Increased  Idle RPM
          Thrust levels for taxi can  be kept the same by using less than
the full complement of engines, but at a higher power output level.  Again
the benefit will be in reducing carbon monoxide and hydrocarbon emissions
which occur  predominately at  low power settings.  Using fewer engines  (and
less fuel) per aircraft during ground operations will also provide an
across-the-board cut  in emissions.  Implementation of such a change is
straightforward with  the sole exception of requiring fire-safety pro-
visions at the ends of. runways while departing aircraft are starting
engines.  At  least one airline currently saves fuel by shutting down the
center  engine on arriving Boeing 727  aircraft, while taxiing to the gate.

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                                                                     56
          The question with this method of controlling emissions at air-
ports  is how many engines are minimally needed for taxi.  In the extreme
it  is  possible to taxi with a single engine.  This would provide the maxi-
mum reduction in emissions.  Airline pilots do not expect that the un-
balanced thrust from single engine taxi of two and four engine aircraft
would  be unacceptable; tests are nonetheless needed to confirm the safety
of such operation as a standard procedure.  A more serious factor milita-
ting against use of a single engine is the power level which would be re-
quired to resume taxi after the aircraft comes to a complete stop.  With
fully  loaded aircraft on slight grades a  100 per cent power output from
a single engine may well be necessary to  resume taxi.  The hazardous jet
blast  area would have to be extended from a current value of 150 feet to
more than kQO feet.  The ramifications of the increased jet blast might
require substantial modification of airport taxi procedures and rules.
          The extent to which the number of engines used during taxi can
be reduced thus remains unclear.  For this reason two sets of reduced.
emission numbers have been derived:  one assuming single engine opera-
tion and the other, two engine operation for all commercial  aircraft.
Table  33 summarizes the reduction in emissions which would result if only
one or two engines were operating (at a higher power level)  during taxi.
The reductions for the taxi mode are substantial-- particularly if single
engine taxi proves to be acceptable.  As discussed in the next section of
the report, the savings in fuel from single engine taxi  operation would
surely be attractive to the airlines.

             Controlled  Engine  Start-Up  and  Gate Departure
          The idea is to restrict engine operation while the aircraft is
on the ground to that required for taxi.  The engines would be shut down
at the gate.  They would be started under the direction of a ground traf-
fic control system which, among other things, would eliminate delays at
the end of the runway.  Such an airport ground traffic control  system offers
many evident advantages besides reduced emissions.  However,  several  factors
militate against its implementation.  The traffic control  system would have

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                                                                     57
 to be extremely complex  if  current  runway  utilization  levels are  to be
 maintained.   Moreover, a  prime  reason  for  current delays at th'e end of
 the runway is the unavailability  of gates  for arriving aircraft.  Air-
 lines di spatch aircraft  simply  to open  a gate,  regardless of how  soon
 clearance for take-off will  be  granted.  Thus either more gates,  or an
 intermediate parking area for departing aircraft, or more uniformly
 scheduled traffic levels  would  be necessary  to  implement this  ground
 operation change.   Nevertheless the orderly  growth of  air transport
 operation will  doubtlessly  require  automated ground control to maximize
 airport  utilization.  Thus  this method  for reducing emissions  is  likely
 to appear increasingly practical  with  time.
           This control method will  eliminate delay mode emissions, as
 defined  in Reference 6.   In the case of Los Angeles  International Air-
 port  mode times are as follows:
              Mode                       Time
           Taxi                  12 minutes
           Delay                112  seconds
           Maintenance          69 seconds  at idle power
                                23 seconds  at cruise power
 Table 3^ summarizes the  aircraft  emissions at Los Angeles Airport
 which result from each mode of  ground  operation.  Table 35 gives  the
 reduction of the emissions  achievable  by eliminating the delay mode.
 Carbon monoxide and hydrocarbon levels  at  Los Angeles  Airport  can be  re-
 duced by about 10 per cent.  At other  airports, where  the delay mode
 represents a larger fraction of ground  operation time, the reduction  can
 be more  dramatic.

                 Intermediate Passenger Transportation
           From the point  of view  of emissions the use  of lounges  for
 transporting passengers  to  and  from aircraft is attractive only if the
 aircraft can be parked near the runway  to  be used.  Otherwise  taxi times
.would not be markedly reduced from  those of  current operation.  Ideally
 aircraft parking areas would be located adjacent to the runways,  midway

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                                                                    58

along their length.  Even then the minimum taxi time will correspond
to the runway length, which is not a substantial reduction over current
taxi times.  Moreover., practical  safety requirements will increase the
taxi distance since parked aircraft should not be exposed to the hazards
of landing aircraft.
          The general conclusion, then, is that modifying existing airports
to use intermediate passenger transportation between the terminal and  an
aircraft staging area is unlikely to reduce aircraft emissions.  The stag-
ing area at Dulles  International  Airport,  for example,  is no closer on the
average to the ends of the runways than is the terminal.  Introducing a
staging area for each individual  runway at existing airports is scarcely
feasible since land shortage is already a problem at most.  New airports
designed to stage aircraft in the vicinity of runways might show some
advantage in emissions,  but the advantage would be slight.  Current air-
port design practices already attempt to locate the terminal to minimize
taxi times, commensurate with safety.  Even should lounges be pollution-
free, then, it is doubtful that airport emissions will  improve with the
mobile lounge type of operation.

                          Towing  of  Aircraft
         •Using auxiliary vehicles to tow aircraft around airports will
dispense with aircraft emissions  from the taxi mode altogether.  Tow
tractors would be used not only to move the aircraft clear of the gate,
but then to tow.the aircraft to a staging area at the end of the runway.
Once clearance is granted, engines would be started at the staging area.
Arriving aircraft would  correspondingly shut down engines at the end of
the runway and would then be towed into the gate.  This type of operation
has on occasion been contemplated in the past because of concern with
jet blast and aircraft maneuverability (for example, by Pan American dur-
ing the advent of turbojet powered commercial aircraft).  The crucial  dis-
advantage stems from a'maximum speed capability of below 10 miles per  hour
for current tow vehicles.  Since  taxi times would more than double, towing
aircraft around airports would require radical revisions of airport pro-
cedures and of airline schedules.

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                                                                     59
          The effectiveness of towing in reducing airport emissions in-
volves a trade-off between reduced aircraft and increased tow vehicle
emissions.  The trade-off is defined on the basis of kilometers travelled,
assuming an aircraft taxi speed of 17.5 kilometers per hour.  The values
of aircraft emissions for the taxi mode (as per Ref 6) are given in Table
36.  This table also indicates values for diesel powered tow vehicles ob-
tained from Reference 31; tractors are assumed to use 17 litres per kilo-
meter.  Comparison of aircraft and tow vehicle emissions shows that even if
tractors were required to do a double journey, there would be substantial
reductions of carbon monoxide and hydrocarbons for most of the aircraft
classes.  However, NOx emissions might increase to an unacceptable level.
          Table 37 shows the effect of eliminating the taxi  mode emissions
entirely.  These values should be taken in conjunction with those of Table
36 to obtain the actual reduction from using tractors.

               Use Ground-Based Auxiliary  Power  Equipment
          There are two ways in which on-board auxiliary power units could
be eliminated from use while at the gate:   by using portable electric and
air supplies or by equipping each gate with a centrally supplied air and
electric system.  The latter method is of limited practicality except pos-
sibly for a newly designed airport.  Mobile units are more feasible with
exi sting ai rports.
          The emissions for on-board auxiliary power units are given in
Table 38.  They are based on those for turboprop engines at take-off
conditions (Ref 6), scaled according to fuel flow rate.   API) operating
details have been obtained from an information sheet on the GTCP-85, pub-
lished by Garrett, and from Reference 11.
          Table 38 also gives the reduction in emissions which would re-
sult from eliminating the use of on-board  auxiliary power units.   The re-
duction is essentially negligible.

     Use Auxiliary Equipment  for  Emptying  Fuel  Drainage  Reservoirs
          Fuel  which collects in the engine drainage reservoirs is cur-
rently dumped as part of the take-off procedure.  The emission levels

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                                                                    60
associated with this operation at Los Angeles International  Airport are
indicated in Table 2**.  A demonstration is being held on August 18, 1971,
of an auxiliary device which extracts and stores the fuel  in the drainage
reservoirs prior to aircraft take-off.  This device is assumed to be 100
per cent effective from the point of view of emissions.   Thus, all  emis-
sions from fuel dumping shown in Table 24 would  be eliminated by imple-
menting this ground operation control procedure.

Conclusions
          Table 39 summarizes the reductions in  carbon monoxide and hydro-
carbon emissions which would result at Los Angeles International Airport
from the seven suggested ground operation changes.  The distribution of
activity among aircraft classes (Ref 6) for the  first two control  methods
has been taken as follows:
                    Aircraft Class           Per Cent
                           2                     3
                           3                    56
                           4                    22
                           5                     6
                           6                    13
Pollutants other than CO and hydrocarbons appear to be less  affected,
although NOx emissions may increase with the use of tractors to tow air-
craft.  By combining minimal number of engines with controlled departure
to eliminate runway delays, a substantial reduction in emissions can be
achieved— indeed a reduction at least comparable to the use of tow
vehicles.  Use of passenger lounges and avoidance of using on-board APU's
offer no advantages in reducing emissions.  The  maximum effect obtainable
by combining the various control methods is a reduction of emissions to
about 50 per cent of their uncontrolled level for this airport, assuming
two engine taxi; and to about 40 per cent, assuming single engine taxi.

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                                                                    61
               IMPLEMENTATION COSTS AND TIMES OF CONTROL
               METHODS:GROUND OPERATIONS MODIFICATIONS
          This section of the report presents estimates of the costs and
times required for implementing various ground operation changes to con-
trol aircraft emissions.  Constraints on feasibility which are difficult
to assess in terms of time and money required for implementation are also
reviewed.  The effectiveness of the different ground operation changes in
controlling emissions is discussed in the preceding section.   Attention
here is confined to the feasibility of the changes independently of their
effectiveness.  Seven operation changes are examined:
          1.  Increase engine idle RPM.
          2.  Use minimal engines for ground operations and increase the
              idle rpm of these engines.
          3.  Reduce unnecessary engine time by a system for controlling
              engine start and gate departure.
          k.  Reduce taxi time by parking aircraft near runways and using
              auxiliary vehicles to transport passengers to and from the
              terminal.
          5.  Minimize engine time by towing aircraft between runway areas
              and the terminal.
          6.  Provide ground-based auxiliary power supply in order to
              eliminate use of on-board auxiliary supply units while at
              the gate.
          7.  Use auxiliary equipment for emptying the fuel drainage
              reservoirs of each engine.
Time and cost estimates have been made for a single representative airport,
Los Angeles International Airport.  Costs will necessarily vary from air-
port to airport.  The basis, for making the estimates is accordingly dis-
cussed so that comparable numbers for other airports can be derived.

Basis for Estimates
          The fundamental assumption made in evaluating the feasibility of
the seven ground operation changes is that current operation levels at

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                                                                    62

Los Angeles International Airport remain in effect.   Specifically,  the
peak hour load was assumed to be 120 operations involving 10,000 passen-
gers.  LA currently has 77 gates, but some of these  must be paired  when
servicing Boeing 7^7 aircraft.   It was therefore assumed that servicing
facilities for 75 aircraft must be available at any  one time-- either
gates or parking facilities.   Five categories of cost have been distin-
guished:  land, construction, equipment, automation  procedures, and op-
erating.  Each of these is defined and the ground rules for deriving
numbers are described below.   The bases for the cost estimates for  each
operation change are summarized in Table **0.
          Additional land purchase is needed for those ground operation
changes which require aircraft parking facilities other than those  at
the terminal.   Space required for servicing varies from aircraft to air-
craft, and provision for maneuver must be made.  For estimation purposes,
an aircraft was assumed to require an average of 1.2 acres of parking space.
Land purchase prices in the vicinity of airports vary widely.  A represen-
tative price of $50,000 per acre was assumed in this study, which corres-
ponds to assessed valuation in the vicinity of Logan International  Airport
in Boston.
          Two types of construction costs can be incurred in implementing
ground operation modifications:  additions or alterations to the terminal
facility and additional taxiway and aircraft parking surfaces.  Terminal
construction costs have been estimated from the costs required to modify
gates when the 7**7 aircraft were introduced.  Surface costs have been
predicated on 12 inch thick concrete, at a cost of $500,000 per acre of
surfacing.
          Different suggested ground operation changes require purchase of
different types of new equipment.  Use of tractors to tow aircraft  between
the terminal and the runway areas will require purchase of additional tow
vehicles.  At a minimum it was assumed that 80 vehicles would be needed to
service 75 gates at peak load without inconvenience.  Airlines currently
maintain about 15 tow vehicles per twenty gates.  Thus, about 25 new trac-
tors would be needed at LA International Airport.  The price of tractors
varies from $20,000 for one adequate for a Boeing 727 to more than  $50,000

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                                                                    63
for wide-body aircraft.  An average price of $30,000 per tractor was
assumed.
          Use of lounges to transport passengers between the terminal
'and the aircraft will require purchase of lounges.  At Dulles Inter-
national Airport lounges costing over $200,000 can transport 110 passen-
gers at a time.  One such lounge per gate should more than suffice for
peak hour loads at LA International.
          Mobile auxiliary power units cost approximately $20,000 for air
supply and $15,000 for electrical supply.  Again the availability of one
air supply and one electrical  supply unit per gate should suffice for
eliminating use of on-board auxiliary power units on the ground.  It was
assumed that currently only 50 per cent of this requirement is satisfied.
          To empty at the gate the fuel which collects in the fuel drain-
age reservoirs will require purchase of the proper auxiliary equipment.
An FAA demonstration of such a piece of equipment was held on August 18,
1971.  This particular design costs $500.  LA International Airport would
require 75 of them-- one per gate.
          In initiating a complicated ground control system, automation
equipment will be needed— in particular, a computer system with rapid
information through-put capacity and with auxiliary communication equip-
ment between aircraft and control.  For estimation purposes an IBM 360-65
computer was assumed as a bench mark.
          Initiation of a ground control system will also require the de-
velopment and implementation of automated procedures.  If computer control
is to be adopted, programs will have to be developed to provide the computer
with techniques for maintaining control.  Programming cost consists pri-
marily of labor at roughly $30 per man hour.  Even without a computer con-
trolled ground traffic pattern, new schedules and procedures will be needed
to implement either the use of tow vehicles or passenger lounges.  Again a
labor cost of $30 per man hour was assumed.
          Various types of operating costs were recognized.  Aircraft op-
erating expenses on the ground were estimated on the basis of fuel costs
at idle for JT8D engines.  The basic rule is that each engine consumes 1200
Ibs/hr of fuel during idle, at a cost of $48 per hour.  Operating enqines

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at an increased idle speed, based on Boeing 727 experience, increases
consumption to 1800 Ibs/hr.  Los Angeles International Airport had
JtO.OOO operations during 1970.  If it is assumed that the average opera-
tion involved 20 minutes of idle and taxi time and that the average "air-
craft" has 2.7 engines, then the ground fuel consumption at LA alone is
$17,000,000 per year.   The cost savings which would result by reducing
aircraft engine ground operation are accordingly of large potential.
These cost savings are in part balanced by the additional  costs for labor
and fuel used by auxiliary vehicles.   They are also likely to be balanced
by the reduction in total capacity which results when ground operations
require significant increases in time.  The assumed incremental operating
costs described below reflect these various considerations.
          In estimating the time required to implement each ground opera-
tion change it was assumed that purchase of land and of equipment would
encounter no unusual problems.  Construction times and times required for
introducing automation were estimated on the basis of current experience.
Time estimates should be regarded as quite approximate since numerous
social  and political factors may interfere with the rapid implementation
of ground operation changes.

Discussion of Results
          Table k\ summarizes the costs and times required for implementing
each of the seven considered ground operation changes.  Money and time,
however, are not the only factors affecting the feasibility of these changes.
Some changes have advantages other than those associated with aircraft emis-
sion levels, while others involve disadvantages in terms of airport operation
which cannot readily be assessed numerically.  For this reason a synopsis of
the method of implementation and the advantages and disadvantages of each of
the seven changes is presented below.  Table k2 summarizes the factors which
affect the implementation of the changes.  Included in the table are the re-
quirements for implementation, advantages other than emissions, and con-
straints other than time and cost.

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                                                                    65

                           Increase Idle RPM
          If all engines were to be operated on the ground at an in-
creased idle RPM, fuel  consumption would obviously increase.   The in-
creased operating cost shown in Table 41 is predicated on this assump-
tion.  The extent to which the idle RPM can increase is constrained  by
the capacity of the aircraft brakes— in particular, by the need to  avoid
overheating and excessive wear of the brakes.   Implementation of an  in-
crease in idle RPM requires only a modification of cockpit procedure since
the idle speed is fully under the pilot's control.  Thus no prominent
initial costs would occur with implementation.
          This control  method would probably not be adopted without  a cor-
responding reduction in the number of engines  operating, so that total air-
craft thrust would remain essentially the same.  Brake problems would in
this way be eliminated.  The net effect on the operating cost of this com-
bination of control methods, as discussed below, could be a substantial re-
duction in fuel expenditures for ground operations.  American Airlines, for
example, cuts Boeing 727 fuel costs on the ground by shutting down the center
engine and by operating the out-board engines  at higher output levels.

                 Reduce Number of Engines During Taxi
                         and Increase Idle RPM
          Total aircraft thrust during ground  operations can be maintained
by using fewer engines operating at higher power output levels.  Aircraft
emissions would-be reduced on two counts:  shut-down engines would produce
no emissions, and engines operating at higher  output would produce less
carbon monoxide and hydrocarbon emissions.  The change  in airport pro-
cedure would call for unnecessary engines to be shut down upon landing and
not to be restarted until at the end of the runway prior to departure.
Whether one or two engines would be necessary for effective ground opera-
tions to be maintained at airports remains an open question.  However,
except for an answer to this question,  implementation of the change would
not be difficult since no equipment purchase or construction is entailed.
Indeed, the suggested change in effect provides a more efficient method for
achieving ground thrust requirements.  Thus reduced fuel consumption would
be a direct consequence.

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                                                                    66

          The principal constraint on the minima] number of engines
needed is the thrust required to resume taxi once the aircraft comes to
a complete stop.  A fully loaded Boeing 727 requires approximately 50 per
cent of take-off power from two engines to  resume taxi following a pro-
longed stop on a slight grade.  Single engine operation would require a
100 per cent power level.  The resulting jet blast along taxiways may prove
hazardous.  More space (e.g., in excess of ^00 feet) between aircraft wait-
ing for departure at the end of the runway would doubtlessly be needed with
single engine operation.  There is also a question on the safe maneuverability
of two and four engine aircraft taxiing with unbalanced thrust produced by
a single engine.  Still, two engine ground operation appears reasonable with
most commercial  aircraft, and single engine operation is not out of the ques-
tion.  An airport procedure change to provide fire protection equipment and
personnel would be necessary were engines to be started not at the gate, but
at the end of the runway.  A slightly more elaborate staging area at the end
of the runway might also be needed at some airports.
          The initial costs in implementing this ground operation change
would be negligible.  Reduced fuel consumption during ground operations
would yield operating cost savings, as indicated by the negative numbers
in Table k\.  In particular, single engine operation would result in a $7-5
million annual cost savings at Los Angeles  International Airport, and two
engine operation would result in a $3 million savings.  The additional labor
cost for fire protection at the end of the  runway is negligible by compari-
.son-- less than one-half million dollars annually at LAX.  Implementation of
two engine operation should require little  time since all factors other than
fire protection are at the pilot's command.  Single engine operation should
await a series of tests to establish its practicality and safety.  Since
fuel costs as well as" emission levels show decided gains from using fewer
engines, a more detailed examination of this change is surely merited.

                       Controlled Gate Departure
          The idea'is to restrict engine operation on the ground to that
required for taxi.  The engines would be shut down at the gate.  They

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                                                                     67
would be started under a ground traffic control  system which, among other
things, would eliminate delays at the end of the runway.   Such an airport
traffic control system offers many evident advantages, but several factors
mi 1i tate against i t.
          The fundamental problem centers on the incompatibility of the
times required for arrival  and departure procedures if the latter are
initiated from the gate rather than from the end of the runway.  The time
required for an aircraft to proceed from a final holding pattern to land-
ing is of the order of magnitude of hundreds of  seconds.   The time re-
quired for an aircraft to be towed clear of the  gate,  to start engines, to
taxi  to the end of the runway, and to take-off is more of the order of mag-
nitude of thousands of seconds.  For example, the average taxi time alone at
LA International Airport is 12 minutes (Ref 6).   Moreover, the time from en-
gine start to take-off is not uniform since it depends on the distance from
the gate in question to the runway in use.  For  a controlled gate departure
procedure to work with current peak load conditions, a complicated computer
based system with automated communication techniques would be needed.  The
computer would be programmed on the basis of queuing theory to supply air-
craft at the runway end automatically.  The program would take into account
the time required for the aircraft to reach the runway from its gate as well
as the sequence in which permission to start is  requested.  Contingencies
associated with arrivals, with weather, and with emergencies would be taken
into consideration.  Procedures for assuring fair treatment of all airlines
regardless of terminal location and procedures for continuous monitoring
after permission to start, could in principle be introduced.   Implementation
of so complicated a ground control system would  scarcely be straightforward,
particularly given the current complexity of airport procedures with minimal
ground control.
          A second constraint on controlled gate departure is that much of
the current delay at the end of runways results  from an insufficient number
of gates.  Airlines dispatch aircraft to open a  gate for use even though
the aircraft will be unable to take off.  Thus,  a second requirement for
controlled gate departure is either an increase in the number of gates or a
parking area from which the ground traffic control system would take over.

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                                                                     68

 For  example, aircraft could be towed to the parking area under direction
 of .the  computer when gate space  is needed, but when engine start per-
 mission can not yet be granted.  Provision for 20 per cent of the gate
 capacity  for such  intermediate parking should suffice except during ex-
 traordinary circumstances.
          A final  constraint on  controlled gate departure is the need to
 supply  electrical  power and air  conditioning without the use of the air-
 craft engines.  Boeing 707's, 720's, and McDonnel1-Douglas DC-8's do not
 have on-board auxiliary power units, so that ground-based facilities would
 be required for these planes.
           Introduction of an automated ground control system, as indicated
 in Table  k], involves substantial effort and expenditures.  Were this
 ground  operation change viewed purely in terms of reduced aircraft emis-
 sions,  it would be of dubious merit.  However, the orderly growth of com-
 mercial air transport in the present social climate is likely to require
 more effective utilization of existing airports.  Automated ground control
 would surely provide one step toward improved utilization, though the step
 may  seem  small compared to improved air traffic control.  Thus in judging
 the  costs for controlled gate departure, shown in Table k\, the reader is
 encouraged to keep the total airport picture in mind.

                 Intermediate Passenger Transportation
          From the point of view of emissions the use of lounges  for trans-
porting passengers to and from the aircraft is attractive only if the air-
craft can be parked near the runway to be used.   Otherwise taxi  times would
not be markedly reduced from those of current operation.   Parking space for
75 aircraft near the runways at LA International  is not remotely  available.
Safety questions may also discourage locating parking areas near  runways.
The large costs associated with modifying an existing airport to  this type
of operation result to a dominant extent from the cost of a parking area.
In the case of a new airport this type of operation would appear  far more
practical  since terminal  construction costs can be reduced in far greater
proportion than the cost of the  lounges and parkinq space.

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                                                                     69

          To implement this change at an existing airport requires purchase
of land,  construction of parking space near runways, purchase of passenger
transportation vehicles, and possibly some added purchase of aircraft ser-
vice and  power supply vehicles.   Again either ground-based or on-board
auxiliary power units will  have to suffice for air conditioning.  Obviously
airline schedules would also require revision.  It might bfe competitive on
a cost basis simply to build a new airport using this type of operation.
Nevertheless, from the point of view of emission control the feasibility
of this operation change is contingent upon whether aircraft parking areas
can be made available quite close to runways.  Since taxi time correspond-
ing to runway length will at a minimum remain necessary, the gain in emis-
sions will probably not be significant.  The operating cost reduction in-
dicated in Table ^1 is predicated on a 50 per cent  reduction in taxi and
idle time.  A more realistic assumption might be no reduction in taxi and
idle time,  in which case the operating cost at LAX would increase by $5
mi 11 ion per year.

                           Towing of Aircraft
           The principal difficulty  in towing aircraft between the runway
and the terminal is the substantial  time the operation would require.  Tow
vehicles are currently  limited to 8 miles per hour  loaded (15 miles per
hour unloaded); this speed drops off markedly on a  grade (Ref 32).  Thus
the average  time required  from  the  gate until departure  at  LA  International
Airport will  increase  from  \k minutes,  to at  least 30 minutes.  The average
time  required  for  towing into the  gate after  landing will be around  20
minutes,  as  compared  to a current  taxi average of  less  than  7 minutes.   Such
 increases  in  ground  time would  necessitate  revision of  airline  schedules,
particularly  those associated with  short-haul and shuttle type  flights.  Thus
the  implementation cost of a  towing operation is a  minor consideration com-
pared  to  potential ramifications of  the time  loss problem.  Several man-years
of scheduling effort will be  required  per airport.  Some new aircraft may  be
needed to maintain current capacity.   There  is even the  possibility of  lost
revenue because, for example, the  gate-to-qate  time from Los Angeles  to  S.i".
Francisco will double.

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                                                                    70

          In assessing the cost of towing aircraft, several assumptions
were made.  First, it was assumed that with proper scheduling the increased
ground time could be absorbed in such a way as to avoid loss of revenue to
the airlines.  Such scheduling would require larger than normal  implementa-
tion labor.   A major operating expense would result from increased crew-
hours during towing.   It was assumed that for ^00,000 operations at Los
Angeles Airport the crew time would increase by 150,000 hours, at a cost
of $200 per crew hour.  When this expense is added to the cost of operating
the tow vehicles, all cost savings associated with aircraft engine fuel con-
sumption are offset.
          Implementation of the towing procedure thus requires not only ad-
ditional  towing vehicles, but also schedule modifications to allow for more
than a 100 per cent  increase in ground taxi times.  The alternative of new
tow vehicle designs capable of 30 mile per hour operation is possible, but
it would require the development of a new generation of tow equipment and
the formulation of quite different ground rules for towing safety and re-
liability.  Towing would finally require the on-board auxiliary power units
to supply adequate air conditioning throughout the towing period; special
provisions would be needed for those aircraft without on-board auxiliary power
uni ts.

                  Ground-Based Auxi1iary Power Supply
          There are  two ways in which on-board auxiliary power units could
be eliminated fromuse while at the gate:  by using portable electric and
air supplies or by equipping each gate with a centrally supplied air and
electric system.  The latter method is of limited practicality except pos-
sibly for a newly designed airport.  With existing airports mobile units
are more feasible.   Implementation will require purchase of adequate equip-
ment.  From the point of view of over-all ground operation, ignoring emis-
sions, experience with the first generation of jet powered aircraft has led
to the standard use of on-board auxiliary power units.  The operational com-
plexities associated with ground-based equipment are well known (Ref 33).

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                                                                    71
                     Auxiliary Equipment to Empty
                       Fuel  Drainage Reservoirs
          Equipment has recently been developed for extracting and tempo-
rarily storing the fuel which collects in the engine fuel  drainage reser-
voirs (Ref 3^).  The device hooks up to each engine in turn,  and it would
be used as part of the standard aircraft servicing procedure  at the terminal
gate.  The devices cost $500 per unit.  One per gate should suffice.   Thus
at Los Angeles International Airport only a $38,000 expenditure is needed to
eliminate fuel dumping from the take-off procedure.  The equipment in ques-
tion is currently being demonstrated.  Implementation could proceed quite
rapidly once equipment is purchased and personnel are trained.

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                                                                      72

                         EMISSIONS MEASUREMENT

 I ntroduct ion
          Reliable methods of measuring pollutant emission rates from
aircraft engines are required to support a program of emission control.
Emission measurements are required to evaluate the effectiveness of
control methods, and specific measurement methods must be incorporated
in emission control standards.
          An assessment has been conducted of the state of emission
measurement technology to determine whether measurement techniques are
sufficiently well-advanced to support the development of emission con-
trol methods and the implementation of emission standards for aircraft
engines.  The conclusion drawn from this assessment is that current
measurement technology will meet most of the requirements of an emission
control program.  Certain measurement techniques are inadequate at present
but development of improved techniques appears to be proceeding at a
satisfactory rate.
          Measurement of emission rates from an aircraft engine involves
three major requirements:
          1.  A test procedure specifying engine operating conditions.
          2.  A sampling technique for obtaining a representative sample
              of exhaust gas.
          3.  Analysis instrumentation for determining pollutant con-
              centrations  in  the exhaust gas sample.
Aircraft engine manufacturers and certain government agencies have devoted
substantial effort toward providing for these requirements for emissions
measurements for turbine engines.  Representatives of these organization
have formed a committee under the auspices of the Society of Automotive
Engineers,  referred to as the SAE E-31 Committee, for the purpose of
defining standard measurement procedures and equipment.  This assessment
of turbine  engine emissions measurement technology is based to large degree
on the work of the SAE E-31 Committee.

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                                                                      73

          Less progress has been made in defining measurement technique
specifically applicable to aircraft piston engines.   The techniques which
have been developed for automobile engines are applicable in general to
ai rcraft engines.

Test Procedures
          Two types of test procedures can be used in measuring emissions
from mobile sources.  In the first type, emission rates of all  pollutants
of interest are measured at each steady state engine operating  condition.
These measured rates are then averaged, with appropriate weighting factors,
to determine the total emissions for a complete operating cycle.   In the
second type of procedure,  the engine is actually operated through a com-
plete operational  cycle and a composite sample is collected and analyzed.
The weighted average emission rate for the operational cycle is obtained
directly.  This procedure  is more effective for operating cycles  which
involve transient  operations such as starting and acceleration.
          Only the first type of procedure has been used to date  with air-
craft engines.  Operational cycles which have been defined for  aircraft
generally include  steady operating conditions only.   An additional factor
is that current sampling techniques for turbine engines require long
sampling times to assure that representative samples are obtained.  With
this requirement,  it  is not feasible to obtain composite samples  for a
complete operating cycle.
          Test procedures  for standardized emission measurements  should
be based on a sequence of  measurements at well-defined, steady  operating
conditions.  Conditions which affect emission rates should be defined
carefully.   These  include  engine speed and power level, fuel type,  inlet
air temperature, pressure, and humidity.

Exhaust Sampling Techniques

                            Turbine Engines
          The primary objective in exhaust gas sampling is obtaining a
representative sample of exhaust gas of a known quantity or at  a  known

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flow rate.  Apparatus used for sampling generally consists of a probe,
sampling  line, a flow measuring device, a pump capable of drawing the
desired flow rate through the system, and collection devices for captur-
ing pollutant samples.
          Effort is underway to standardize the design of sampling probes
(Ref 35).   The SAE E-31 Committee recommends that probes be of stainless
steel with an orifice area such that the principle pressure drop occurs
in the orifice itself.  If a mixing probe is to be used, they specify that
all sampling holes be equidiameter  (Ref 36).  The probe need not be designed
to achieve isokinetic sampling since departures from this condition only
cause errors for particulates whose diameters are greater than 3-5 microns.
Particulate emissions from aircraft engines are primarily less than 1
micron in diameter.   As a notable example of this lack of need for isokinetic
sampling,  Pratt 5- Whitney (Ref 37)  tested an aircraft engine exhaust with
two probes installed back to back:  one facing upstream; the other down-
stream.  No detectable difference in the smoke density was observed as
measured by the two probes as a function of engine power level.  Further,
probe orientation was not critical as long as they were stationed within
the exhaust stream and secondary air had not diffused into the stream.
          The SAE E-31 Committee and others (Refs 38 and 39) have found
that multipoint sampling of engine exhausts is necessary (due to wide
spatial variations in stream characteristics) in order to achieve repre-
sentative values of engine emission rates.  The SAE therefore recommends
that samples be collected at at least twelve locations at a minimum of
three different radial positions  in each of four sampling quadrants.  The
location of these twelve points is  specified by the E-31 Committee; pro-
cedures are also identified for point location if more than twelve samples
are collected.  Either mixing or  individual probes are acceptable (Ref 36).
The SAE also recommends that the axial sampling plane be no further than
one exit nozzle diameter from the engine exhaust.  However, with after-
burning engines, combust.ion is by no means complete at the engine exit
plane.  Champagne (Ref *+0) reports  that the Arnold Engineering Development
Center is conducting tests to produce preliminary solutions to this problem;
The E-31 Committee will attempt to write a separate standard for measurement
of emissions from afterburning engines later this year.

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                                                                      75
          The sampling line, which conveys the gas sample from the probe
to the collection and measurement apparatus, must be designed such that
no changes in sample composition or physical state occur during transit.
The line must therefore be short, of small bore (0.18 to 0.32 in I. 0.,
Ref 36), and be constructed of materials  (stainless steel or Teflon)
which do not adsorb or react chemically with pollutant materials (Ref 41).
The line must also allow free passage of particulate matter.  As an
illustration of the necessity for these requirements, Reference k2 con-
tains a discussion of the reduction of NOX by CO when catalyzed by certain
metals frequently used in sample lines.   In sampling engine exhaust gases,
it is also necessary to maintain the sampling line temperature at a level
at which condensation of organic vapors and water do not occur (about 350
deg F, Ref 36).  This requirement is more severe with turbine engines
than with gasoline-fueled piston engines.  Turbine engine fuels, which
have higher boi1 ing points than gasoline, give rise to organic emissions
which also have high boiling points.  This requirement for heating the
sampling line often is neglected; however, the E-31 Committee has recom-
mended in their test procedure that sample lines be heated to 350 deg F
to minimize this adsorption/desorption phenomenon.  At the present time,
line heating is accomplished primarily via electrical heating tapes;
however, their use has been somewhat problematic and heat transfer fluids
may be employed in the future (Ref 43).
          The types of pollutant collection devices to be used in a sampl-
ing system depend upon the measuring techniques to be employed.  Many
measuring techniques do not require pollutant collection, but indicate
pollutant concentration directly by measuring some property of the gas
sample.  These techniques are utilized either by connecting the measuring
device directly to the sampling system, or by collecting a gas sample in
a container (grab sample) and transporting it to the measuring device.
Separate (heated) sample lines may eventually be employed for grab samples
to prevent their upsetting the flow into continuous monitoring equipment
(Ref

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                                                                      76
                             Piston Engines
          Sampling techniques for aircraft piston engines are not as
critical as with turbine engines since exhaust gases are thoroughly
mixed when they reach the exhaust stack exit.  Also, fewer condensible
vapors are encountered and particulates generally are not measured.
The sampling technique initially proposed by the Department of Health,
Education, and Welfare for automobile emission measurements (Ref 45)
appear to be appropriate for aircraft piston engines.

Instrumentation
                    Range and Accuracy Requirements
          An analysis has been conducted of the range and accuracy of
the instrumentation necessary to measure emission rates of all pollutants
of concern from aircraft engines.  Allowance has been made for potential
reductions in emission rates resulting from future equipment modifications.

                         Pollutants Considered
          In a previous .characterization of aircraft engine exhaust gases
(Ref 1), Northern Research and Engineering Corporation indicated that emis-
sions that should be considered for control and measurement should include,
but not be limited to:  total organics (hydrocarbons), carbon monoxide,
oxides of nitrogen, sulfur dioxide, carbon dioxide, total particulates,
visible smoke, and odor.  Reexamination of the literature (Refs 46 and 47)
shows that species such as peroxyacyl  nitrates, olefins, and aromatics
(ingredients in photochemical smog); polynuclear hydrocarbons (potentially
carcinagenic); acrolein (aldehyde)  formaldehyde, carbonyls, and unsaturated
hydrocarbons (all apparently related to odor intensity); ozone (oxidant);
lead; and unburned fuel (including  drainage) are now often cited as atmo-
spheric contaminants emitted in aircraft engine exhausts.  The majority
of these species are, however, emitted in extremely low quantities and at
concentrations below which satisfactory continuous measurement techniques
have been developed.  Furthermore,  many of these species are constituents

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                                                                      77
 of emissions which are themselves difficult to measure.   As a result,
 with the exception of total aldehydes and unburned fuel  (including
 drainage), these additional species are omitted from this analysis.
           Until  recently,  nitrogen oxides in aircraft engine exhausts
 were considered  to consist primarily of NO with only trace quantities
 of other oxides.   Recent measurements (Ref 34) with turbine engines  have
 revealed,  however, that NCL concentrations are not negligible under  some
 conditions.   Thus, two measurements for NO and N02, or a combined measure-
 ment for the two species,  are required to indicate total NOX emission rate.

                          Instrumentation Range
           Existing data (Refs 1,  3, 37, 41, and 48 through 54)  on air-
 craft engine exhaust emissions are summarized in Table 43-  The column
 entitled "Recommended Range" in Table 44 gives the suggested sensitivity
 of instrumentation for each pollutant.  These ranges reflect emissions
 levels  of  both piston and  turbine aircraft now and in the near future
 after satisfactory control  methods have been established.   These ranges
 correspond in a  large part to the forthcoming recommendations (Ref 36)
 of the  Society of Automotive Engineers Committee E-31, which as produced
 an "Aerospace Recommended  Practice" (Ref 55) covering the measurement of
 visible smoke from turbine engines under test cell conditions.   The  absence
 of data and  specifications for smoke and odor emissions reflects the
 specialized  nature of these emissions in that they are not measured  and
 quantified in a  conventional manner (Kefs 55 and 56).

                           Instrument Accuracy
          Automated pollution measurement  instruments can,  in general,
measure specie concentration with an accuracy of +  1 - 2 per cent
 (Ref 57).  This sensitivity, however,  does not reflect the circumstances
under which the instruments are required  to operate; that  is, it does
not reflect the entire "system" accuracy  (Ref 58).  Further, these limits
are,  in many cases, far more restrictive  than practically  necessary.    The
accuracies recommended  in Table 44  therefore  reflect the sensitivity which
a given  instrument should be required  to meet, exclusive of  interferences

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                                                                       78

from other pollutant  species,  in characterizing aircraft  engine  exhausts.
 In a majority of cases,  these  recommendations  are consistent with  those
proposed by  the SAE E-31 Committee  (Ref  36).

                         Instrument  Availability
          A  wide variety of  instruments  are  available  for analyzing  exhaust
samples from aircraft  engines.  Broderick  (Ref 59)  compiled a  table  of
measurement  methods in use by  nine  organizations  that  are concerned  with
quantification of aircraft emissions.   In  this study,  NREC contacted
several additional organizations to expand and update  this analysis.
These organizations are:
           1.  Air Force Aero Propulsion  Laboratory;  Captain 0.  L.  Champagne.
          2.  Cranfield  Institute of Technology;  by Dr. R. S.  Fletcher of
              the NREC staff.
          3.  Rolls-Royce  (Derby);  Dr.  Brian Edwards.
          k.  Lockheed-California Company; Mr. E. F. Versaw.
          5*  Southwest  Research  Institute;  Mr. C.  T.  Hare.
          6.  AiResearch Manufacturing  Company; Mr.  J. M.  Haasis.
          7.  U. S. Department  of the Interior, Bureau of Mines; Mr.  R. W. Hum.
          8.  Curtiss-Wright Corporation;  Mr.  T.  P.  Gagandize.
Table ^5 is a compilation of the results of  Broderick's report and of  this
survey.   In several  cases, organizations use more than one method  to  deter-
mine a particular constituent;   in several cases, organizations do  not
measure all of the pollutant species  included  in the table.  The instruments
listed in Table ^5 and alternative  instruments are described in  the Appendix.

Recommendat i ons

                                CO and CO-2
           NREC concurs with  the recommendations of  the SAE E-31  Committee
 (Ref 36) and recommends  the  use of  NDIR instrumentation for monitoring CO
and CO..   Low  level emissions  should be measured  with  supplemental instru-
mentation  such as small  gas  chromatographs.

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                                                                      79
                           Total Hydrocarbons
          NREC concurs with the recommendations of the SAE E-31 Committee
 (Ref 36) and recommends the use of FID instrumentation for monitoring total
hydrocarbons.  Low level emissions should be measured with supplemental
 instrumentation such as small gas chromatographs.  Hydrocarbon distribution
should be determined with gas chromatographs.

                    Oxides of Nitrogen (NO and NOj
          NREC concurs partially with the recommendations of the SAE E-31
Committee and recommends the use of NDUV instrumentation for monitoring
NO^.  However, chemiluminescence monitors are recommended for monitoring
NO because of their greater accuracy at low NO concentrations.

                                  19-2
          NREC recommends that SO. emissions be calculated from the sulfur
content of the fuel rather than measured by any type of  instrumentation.
 If a measurement program is selected, the West-Gaeke wet chemical procedure
 is recommended.  "Faristors" are not reconmended at this time, as they have
not yet been field tested in an aircraft emissions program.

                               Aldehydes
          NREC recommends that the 3-MBTH wet chemical procedure be employed
for measurement of total aliphatic aldehydes.  Formaldehyde should be deter-
mined by the chromotropic acid procedure and acrolein by the 4-hexylresorcinol
method.

                              Particulates
          No instrument can be recommended at present for measuring mass
emission rates of either dry or total particulates.  Filtration or
 impingement techniques are not sufficiently sensitive to measure partic-
ulate concentrations in current engines.   Until suitable instruments are
developed, approximate indications of dry particulate emission rates can
be obtained from correlations with smoke measurements.

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                                                                      80

                                 Smoke
          Smoke should be measured according to the procedures (and
forthcoming sampling modifications) recommended in the SAE ARP-1179
(Ref 55).

                                  Odor
          NREC makes no recommendations for .odor measurement other than
suggesting that dilution thresholds be determined for aircraft exhausts
by means of human odor panels.

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                                                                      81


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                                                                      83
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                                                                      84
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                                                                      85
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                                                                       86
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103-   Stockham,  J.  and Betz,  H. ,  Study of Visible Exhaust Smoke from Air-
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105-   Fish,  B.  R.,  On the Measurement of Odor. Presented at Symposium on
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106.   Dravnieks,  A.,  O'Donnell, A., Scholz, R. ,  and Stockham, J. D. , jjjgs
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108.   Somers,  J.  H. and Kittredge, G. D., Review of Federally Sponsored
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109«   Heylin,  M.,  "Pollution Control  Instrumentation", Chemical & Engineering
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110.   Soderholm,  L. G., "Ultraviolet-Absorption Technique Measures Auto Air
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111.   Groth,  R.  H.  and Zaccardi,  V. A., Development of a High Temperature
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112.   Leonard,  D.  A.,  Feasibility Study of Remote Monitoring of Gas Pollutant
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113«   Leonard,  D.  A.,  Development of a Laser Raman Aircraft Turbine Engine
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                                                                       89
117.   Dix,  R.  E.,  Benek,  J.  A.,  MacDermott, W.  N.,  and Tempelmeyer, K. E. ,
      Experience with a Mass Spectrometer Probe for Studying the Formation
      of Oxides of Nitrogen. Presented at the 64th Annual Meeting of the
      Air Pollution Control  Association, June 27-July 1, 1971.
118.   Bogdan,  L. and McAdams, H.  T.,  Analysis of Aircraft Exhaust Emission
      Measurements (CAL No.  NA-5007-K-1), Cornell Aeronautical  Laboratory,
      Inc., Cornell University,  Buffalo, N. Y., October 15, 1971.

-------
                                     90
TABLES

-------
                                      TABLE 1  - AIRCRAFT CLASSIFICATION SYSTEM
Ai rcraf t
Category
Air
Carrier
General
Av iat ion
Mil! tary
Class
1
2
3
1*
5
6
7
8
9
Ref I
Classi-
f icat ion
—
~
1
2
*4
3
6


Tvpe
Supersonic
Transport
Jumbo Jet
Transport
Long-Range
Jet Transport
Med i urn-Range
Jet Transport
Turboprop
Transport
Business Jet
Piston-Engine
Util ity
Over
1*00,000 Ibs
Gross Weight
100,000 Ibs -
1*00,000 Ibs
Gross Weight
Examples
Concorde
Tupolev TU-IM*
Boeing 7^7
Douglas DC-10
Boeing 707
Douglas OC-8
Boeing 727
Douglas DC-9
Lockheed Electra
Fairchild Hiller
FH-227
Lockheed Jetstar
North American
Sabrel iner
Cessna 210
Centurion
Piper 32-300
Cherokee Six
Boe ing
Stratofortress
Lockheed
Star! if ter
Representative Engine
Model
R-R/Snecma
Olympus 593
P£WA JT9D
P6WA JT3D
P£WA JT8D
Al 1 ison
501-D13
P6WA JT12
Cont inental
10-520-A
P6WA TF33-P-3
P&WA TF33-P-7
Tvpe
Turbojet
Turbofan
Turbofan
Turbofan
Turbo-
prop
Turbojet
Opposed
Piston
Turbofan
Turbofan
Thrust
or
Power
37,290 LB-T
1*7,000 LB-T
18,000 LB-T
11*. 500 LB-T
3)750 ESHP*
.3,300 LB-T
285 ESHP
17,000 LB-T
21,000 LB-T
Engi nes
per
Air-
craft
1*
k
k
2.6
2.5
2.1
1""


Shaft Power



Representative of VanNuys and Tamiami

-------
TABLE  1 - AIRCRAFT CLASSIFICATION SYSTEM  (CONTINUED)
Aircraft
Category
Mil itary
V/STOL
Class
10
11
12
Ref 1
Classi-
fication


7
Type
10,000 Ibs -
100,000 Ibs
Gross Weight
Under
10,000 Ibs
Gross Weight
Hel icopters
and V/STOL
Examples
LTV Crusader
Cessna 172
Sikorsky S-61
Vertol 107
Representative Engine
Model
P&WA J57-P-20
Cont i nenta 1
10-360
General Elec-
tric CT58
Type
Turbojet
Opposed
Piston
Turbo-
shaft
Thrust
or
Power
18,000 LB-T
210 ESHP
1870 ESHP
1
Engine
Pef
Air-
craft


2
                                                                                    NJ

-------
                                 TABLE 2 - TURBINE ENGINES IN THE U.  S.  AIR CARRIER FLEET
                                                      (JANUARY.  1970)
A!re raft
  Class
         Manufacturer

AiResearch Division
Garrett Corporation
         Model

TFE731-2K
TPE331-2-20IA
        Type
                                                                        Turbofan
                                                                        Turboprop
                                                                        Turboprop
Maximum Pov;er
  or Thrust

3500 LB-T
665-715 ESHP
575 ESHP
Number
in Use
                                                                                                                  Total
   2
   3
   3
   3
   \
   2
   3
   3
   3
            Al1ison Divis ion
            General Motors Corporation
            General  Electric Company
Pratt & Whitney
Ai rcraft Divis ion
United Aircraft
Corporat ion
RolIs-Royce Ltd.
                                 501-DI3
                                 501-D22A
                                             CF6-6D
                                             CF6-50A
                                             CJ805-3B
                                             CJ805-23B
                                             CJ610-1.9.6
                                             CF700-2D2
JT9D-3A.7J5
JT3C-6.7
JT3D-1.3B.7
                                             JT8D-I.9.7
                                             JT12A-8
                           Turboprop
                           Turboprop
                                                            Turbojet
                                                            Turbofan
                                                            Turbofan
                                                            Turbojet
                                                            Turbofan
                                                            Turbojet
                                                            Turbofan
Turbofan
Turbojet
Turbofan
Turbojet
Turbofan
Turbojet
Olympus 593                Turbojet
RB.211-22B                 Turbofan
Conway RCo.12MK508.509     Turbofan
Conway RCo. ^2,i»3MK5*40      Turbofan
Spey RSp*4MK5!2             Turbofan
Avon RA-29-533             Turbojet
Spey RSp*4MK5H             Turbofan
Bristol-Viper 522          Turbojet
                        3750 ESHP
                             ESHP
                                                   68600  LB-T
                                                   ^0000  LB-T
                                                   A9000  LB-T
                                                   11650  LB-T
                                                   16100  LB-T
                                                   2850-3100 LB-T
                                                   ^4250 LB-T
                                                                                                                  Total
                                                                                                                  Total
            LB-T
13500
17000-19000 LB-T
17500 LB-T
li*500 LB-T
3300 LB-T
                        37290 LB-T
                        i«2000 LB-T
                        17500 LB-T
                        20370 LB-T
                        12550 LB-T
                        12600 LB-T
                        moo LB-T
                        3360 LB-T
                                                                                                                  Total
                           536
                            Bk
                           620
     161*
      2i+
       8
      10
     206

      6k
     160
    2811
     376
    2881
       8
    6300
                                                                                                               120
                                                                                                                         OJ

-------
                        TABLE 2 - TURBINE ENGINES  IN  THE  U.  S  AIR CARRIER FLEET (CONTINUED)
(JANUARY. 1970)
Ai rcraf t
Class Manufacturer
5 Rol Is-Royce Ltd.
5
5
5
5
5

5 Societe Turbomeca
5

5 United Aircraft of Canada


Model
Dart Da6-MK51*»
Dart Da7-MK532
Dart DalO-MK5**2
Dart Da7-MK529
Dart Da6-MK510
Tyne 12MK515

Astazou X 1 1
Bastan VIC

PT6A-20.27


Type
Turboprop
Turboprop
Turboprop
Turboprop
Turboprop
Turboprop

Turboprop
Turboprop

Turboprop

Maximum Power
or Thrust
1850 ESHP
2230 ESHP
3025 ESHP
2100. ESHP
J670 IStiP
5500 ESHP

731 ESHP
1065 ESHP

579-715 ESHP

Number
in Use
72
1^8
1A8
—
32
36
Total 598
_
-
Total 0
26
Total 26
TOTAL TURBINE ENGINES



Sources:  References 7, 8, 9, 10, and  11
775*4
                                                                                                                   vo
                                                                                                                   -p-

-------
                               TABLE  3A - TOTAL ENGINES  IN THE U. S. GENERAL AVIATION FLEET
                                             (TURBINE ENGINES)  (JANUARY.  1970)
Ai rcraft
  Class

   6
   6
   6
   6
   6
                                                                                     Maximum Pov/er
Number
   6
   6
   6
   6
   6
   6
   6
   6
   6
   6
   6
   6
   6
         Manufacturer

AiResearch Division
Garrett Corporation
A) 1i son Divis ion
General Motors Corporation

General Electric Company
Pratt & Whi tney
Aircraft Division
United Aircraft Corporation

Rolls-Royce Ltd.
            Societe Turbomeca
United Aircraft of Canada
   TOTAL TURBINE ENGINES

   Sources:  References 7, 8, 9,  10, and  11
Model
TPE33I-3U
TPE331-1-15IA
TPE331-143
ATF-3
TFE-731-2K

501-D13

CJ610-1.6.9
CF700-2D2

JT12A-8
JT8D-9.7

Dart Da7MK-529
Spey RSpl4MK5H-8
Viper 522
Viper 601
Dart Da7MK520
Dart DalOMK5i*2-it
Tyne 12MK5I5

Astazou XIV MK1

JT15D-1
PT6A-20.2.28

Type
Turboprop
Turboprop
Turboprop
Turbofan
Turbofan

Turboprop

Turbojet
Turbofan

Turbojet
Turbofan

Turboprop
Turbofan
Turbojet
Turbojet
Turboprop
Turboprop
Turboprop

Turboprop

Turbofan
Turboprop

or Thrust
8*»0 ESHP
665-715 ESHP
575 SHP
1*050 LB-T
3500 LB-T

3750 ESHP

2850-3100 LB-T
14250 LB-T

3300 LB-T
114500 LB-T
-
2100 ESHP
111400 LB-T
3360 LB-T
3750 LB-T
1815 ESHP
3025 ESHP
5500 ESHP

600 ESHP

2200 LB-T
579-715 ESHP

in Use
88
186
222
30
22
Total 5^8
12
Total 12
652
200
Total 852
6142
310
Total 952
562
138
131*
58
76
146
16
Total 1030
26
Total 26
2
1387
Total 1389
                                                                                                               1*809
                                                                                                             vn

-------
                              TABLE   3B - TOTAL ENGINES  IN THE U. S. GENERAL AVIATION FLEET
Ai rcraft
  Class
(PISTON ENGINES)
Manufacturer Model
Avco Lycoming Division 0-235
Avco Corporation 0-290
0-320
0-360
0-5^0
G0-*»80

10-320
10-360
I0-5*»0
TIO-320

Tl 0-360

TIO-5*»0

TIO-5*»1

TIO-5**7

IGSO-*t80

IGSO-5^0

Continental Motors Division 0-200
Teledyne Corporation 0-300
0-*»70
GO-300

W-670
(JANUARY, 19701
Type
Normal Carburation
Normal Carburation
Normal Carburation
Normal Carburation
Normal Carburation
Normal Carburation
and Gear
Fuel Inject ion
Fuel Inject ion
Fuel Injection
Turbocharged Fuel
Injected
Turbocharged Fuel
Injected
Turbocharged Fuel
Injected
. Turbocharged Fuel
Injected
Turbocharged Fuel
Injected
Fuel Injected,
Geared, Supercharged
Fuel Injected,
Geared, Supercharged
Normal Carburation
Normal Carburation
Normal Carburation
Normal Carburation
and Gear

Maximum Power
at Sea Level

115 ESHP
UO ESHP
160 ESHP
180 ESHP
260 ESHP
295 ESHP

160 ESHP
200 ESHP
300 ESHP
                                                                                               200 ESHP

                                                                                               310 ESHP

                                                                                               380



                                                                                               3*»0 ESHP

                                                                                               380 ESHP
                                                                                               100 ESHP
                                                                                               l*»5 ESHP
                                                                                               2*40 ESHP
Number
in Use
                                                                                                                         318
                                                                                                                        1302
                                                                                                                       20AOO
                                                                                                                        7610
                                                                                                                       16200
                                                                                                                         217

                                                                                                                        3010
                           87

                            12

                         2790

                         1150

                           258
                            53

                  Total  57335

                         30600
                          2)80
                         17050
                          1578

                           129

-------
                         TABLE  3B - TOTAL ENGINES IN THE U. S. GENERAL AVIATION FLEET (CONTINUED)
Ai rcraft
  Class
(PISTON ENGINES) (JANUARY, 1970)
Manufacturer
Continental Motors Division
Teledyne Corporation
Curt iss-Wr ight Corporation

Fairchild Engine Division
Fairchild Aircraft Company
Franklin Engine Company, .Inc.
Subsidiary of Allied Aero
Indus tries
Jacobs-Page Aircraft Engine
Company
Pratt & Whitney
Aircraft Division
United Aircraft Corporation
•
Model
10-360
10-1*70
10-520
TSI-520
GTS 10-520
R-975
R1820
R2600
Rl*360
Ranger R6-1*1*OC
2A-120
l*A-235
6A-335
6A-350
R-755A2
R-755B2
R-985
R- 131*0
R-1830
R-2000
R-2800
Type
Fuel Injection
Fuel Injection
Fuel Injection
Turbocharged Fuel
Injected
Fuel Injected,
Geared, Supercharged
Radial
Radial
Radial
Radial

Hor i zontal -Opposed
Hor i zontal -Opposed
Hor i zon ta 1 - Opposed
Hor izontal -Opposed
Radial
Radial
Radial
Radial
Radial
Radial
Radial
Maximum Power
at Sea Level
210 ESHP
260 ESHP
300 ESHP
310 ESHP
1*75 ES.HP
1200 ESHP
1700 ESHP
2200 ESHP
200 ESHP
50-90 ESHP
65-80 ESHP
150-165 ESHP
100-215 ESHP
21*5 ESHP
300 ESHP
1*50 ESHP
600 ESHP
. 1050 ESHP
11*50 ESHP
2300 ESHP
   TOTAL PISTON ENGINES

   Sources:  References 7,, 8,  9, and  11
  Number
  i n
                                                                                                                           1*29
                                                                                                                         12930
                                                                                                                          3330

                                                                                                                            58

                                                                                                                   Total  7321*4
                                                                                                                            3**
                                                                                                                           350
                                                                                                                           136
                                                                                                                           299
                                                                                                                           819
Total
                                                                                                                   Total
                                                                                                                   Total
Total
         55
         55

         26
          8
        21*2
        1900
        2176
                                                                                                                           275
                                                                                                                           669
         92
        1190
        901*
         78
        55*4
Total   2818

     137116

-------
                      TABLE
                                            - TOTAL ENGINES IN THE U.  S.  MILITARY FLEET
                                       (TURBINE AND PISTON ENGINES)  (JANUARY.  1970)
Ai rcraft
  Class

   8
   10
         Manufacturer

General Electric Company

Pratt & Whitney
Aircraft Division
United Aircraft Corporation

Al 1ison Division
General Motors Corporation

Curtiss-Wright Corporation

Pratt & Whitney
Aircraft Division
United Aircraft Corporation
AiResearch Division
Garrett Corporation

Al) i son D ivi s ion
General Motors Corporation
            Avco Lycoming  Division
            Avco Corporation

            Curtiss-Wright  Corporation
    Model
TF39

J57



T56


R-3350

JT3D
TF33
                                     T76
                                     T56
                                     T63
                                     J71

                                     T53
                                     YT55

                                     J&5
                                     R1300
                                     R1820
                                     R3350
        Type

Turbofan

Turbojet



Turboprop


Radial Turbo-Comp.

Turbofan
Turbofan
Turboprop


Turboprop
                       Turbofan
                       Turboprop
                       Turboprop
                       Turbojet

                       Turboprop
                       Turboprop

                       Turbojet
                       Radial
                       Radial
                       Radial
Maximum Power
or Thrust
*»1100 LB-T
18000 LB-T

*»910 ESHP
3^00 ESHP
18000 LB-T
21000 LB-T
6000 ESHP
715 ESHP
15000 LB-T
^910 ESHP
317 ESHP
1900 ESHP
3750 ESHP
10500 LB-T
600 ESHP
1200 ESHP
3*tOO ESHP
Number
in Use
258
2000
Total 2258
1769
200
28
2*400
215
Total **612
826
*4000
1906
135
\2kkS
2*«93
137
11
2069
217
     Including Military  Helicopters
                                                                                                                         oo

-------
                            TABLE  *4  - TOTAL ENGINES  IN THE U. S. MILITARY  FLEET"  (CONTINUED)
Ai rcraft
  Class
(TURBINE
Manufacturer
General Electric Company



Pratt & Whitney
Aircraft Division
United Aircraft Corporation








AND PISTON ENGINES)
Model
T58
T61»
J79
J85
TF30
TF33
J52
J57
J58
J60
T73
J75
F100
R 13*40
R2800
(JANUARY, 1970)
Type
Turboshaf t
Turboshaf t
Turbojet
Turbojet
Turbofan
Turbofan
Turbojet
Turbojet
Turbojet
Turbojet
Turboshaf t
Turbojet
Turbofan
Radial
Radial
            RolIs-Royce Ltd.


   11       Allison Divis ion
            General Motors Corporation

            Avco Lycoming Division
            Avco Corporation

            Continental Motors Division
            Teledyne Corporation

            General Electric Company

            United Aircraft of Canada


   TOTAL MILITARY ENGINES

   Sources:  References 1, 7. 8, 9, and 1
Dart MK 529-8X


J33


0-1435
GO-480

J69
0-1470

J85

T7** (PT6)
Turboprop


Turbojet


Normal Carburet ion
Normal Carburation

Turbojet
Normal Carburation

Turbojet

Turboshaft
Maximum Pov;er
  or Thrust

1870 ESHP
3925 ESHP
17900 LB-T
2900-5000 LB-T

13^00 LB-T
21000 LB-T
11200 LB-T
16900 LB-T
30000 LB-T
3300 LB-T
14500 ESHP
26500 LB-T
30000 LB-T
600 ESHP
2300 ESHP

2100 ESHP
1*600 LB-T


260 ESHP
295 ESHP

1*420 LB-T
2*40 LB-T

2900-5000 LB-T

579. ESHP
                                                                    Number
                                                                    in Use
                                                                                                                          3159
                                                                                                                           1*58
                                                                                                                         10083
                                                                                                                          AOOO

                                                                                                                          1509
                                                                                                                          1307
                                                                                                                          3733
                                                                                                                          6231

                                                                                                                           878
                                                                                                                           208
                                                                                                                          11422

                                                                                                                            22
                                                                                                                            70
Total 57323

         20
        81*4
        1419

       555*4
        173

       3020

        1*32
Total 10*432


      7^625
                                                                          VD
                                                                          VD

-------
                         TABLE  5A - TOTAL ENGINES IN THE U. S. CIVIL HELICOPTER AND V/STOL FLEET
                                       (TURBINE AND PISTON ENGINES) (JANUARY. 1970)
Ai rcraft
  Class
     .'.
   12"
         Manufacturer

AlIison Oivi s ion
General Motors Corporation

Avco Lycoming Division
Avco Corporation
            General Electric Company


   TOTAL CIVIL HELICOPTER ENGINES

   Sources:  References 7, 8, 9, and 11
     Model

250-C18


T53
VO-*O5

V0-5*»0

HI 0-360

IVO-360
                                     T58
                                     CT58
        Type
Turboshaft
Turboshaft
Vert ical-Opposed,
Normal Carburation
Vert ical-Opposed,
Normal Carburation
Horizontal-Opposed,
Fuel  Injected
Vert ical-Opposed,
Fuel  Injected

Turboshaft
Turboshaft
Maximum Power
  or Thrust

317 ESHP


1900 ESHP
265 ESHP

305 ESHP

205 ESHP

180 ESHP
                                               1870 ESHP
                                               1870 ESHP
Number
iri Use
      836


      323
      550

      755

      530

      100
                           281
                            29
     Heli copters
                                                                                                                       o
                                                                                                                       o

-------
                         TABLE  SB - TOTAL ENGINES IN THE U.  S.  CIVIL HELICOPTER AND V/STOL FLEET
                                       (TURBINE AND PISTON ENGINES) (JANUARY. 1970)
Ai rcraft
  Class

   12*
         Manufacturer

AiResearch Division
Garrett Corporation

Avco Lycoming Division
Avco Corporation
            General Electric Company



            Pratt & Whi tney
            Ai rcraft Divi s i on
            United Aircraft Corporation

            United Aircraft of Canada

   TOTAL V/STOL ENGINES

   TOTAL CLASS 12 ENGINES

   Sources:  References 7, 8, 9» and 11
     Model

TPE33I
        Type
                                     0-5^*0
                                     ALF301
                                     J85
                                     YT58
                                     CF700

                                     R2000
                                     PT6A
Turboshaft
                       Geared, Normal
                       Carburation
                       Normal Carburation
                       Turbofan
                       Turbojet
                       Turboshaft
                       Turbojet

                       Radial
                       Turboshaft
Maximum Pov/er
  or Thrust
715 ESHP
                        295 ESHP

                        300 ESHP
                        2730  LB-T
                        2900-5000  LB-T
                        1870  ESHP
                        A250  LB-T

                        1*450  ESHP
                        715 ESHP
jjumber
i n Use
        15


        k(>

        2k

         2
         b
         1
                           285

                           391

                          3795
     V/STOL

-------
                                                                     102

                                   TABLE 6

                            ENGINE CLASSIFICATION


Tl - Small turbine engines (nominally less than 6000 LB-T or equivalent
     shaft horsepower).

                          Examples:  JT12A, T58

T2 - Turbine engines (nominally 6000 to 29,000 LB-T or ESHP).

                          Examples:  JT8D, CJ805

T3 - Turbine engines (nominally 29,000 to LB-T or ESHP and greater)

                          Examples:  JT9D, CF6

 PI  -  Piston  engines  (all  opposed  configuration engines).

-------
TABLE 7
AIRCRAFT TURBINE ENGINE

Engine
Class Manufacturer
Tl-l All ison Div.
TI-2 CMC
TI-3
TI-4
TI-5
TI-6
TI-7 AiResearch D?v.
TI-8 Garrett Corp.
TI-9
TI-10
Tl-ll Avco-Lycoming Div.*
Tl-l 2 Avco Corp.
Tl-13
TI-14 Continental Motors
TI-15 General Electric Co.
TI-16
TI-17
TI-18
TI-19
TI-20
TI-21
TI-22

" Basel ine Engine

Eng ine
Fami 1 y
Model No.
J33
J71
T56
501
T63-
250
T76
TPE331
ATF3
TFE731
151
T55
ALF301
J69
T58
CT58
GE1
GE12
T64
J85
CJ610
CF700




Thrust
Engine or
Type Power
TJ
TJ
TP
TP
TP
TP
TP
TP
TF
TF
TS
TS
TF
TJ
TS
TS
TJ
TS
TS
TJ
TJ
TF

4600
1*910
3750
317
317
715
715
4050
3500
1900
3750
2730
1920
1870
1870
5000
1500
3925
5000
3100
4250

LB-T
ESHP
ESHP
ESHP
ESHP
ESHP
ESHP
LB-T
LB-T
ESHP
ESHP
LB-T
LB-T
ESHP
ESHP
LB-T
ESHP
ESHP
LB-T
LB-T
LB-T

CLASSIFICATION SYSTEM


Type
Combustor No.
CN (6)
CN (6)
CA (1)
CA (1)
A
A
A
A
A
A
A
A
CA (1)
CA (1)
CA (1)
A
A
A
A
A

; A G
620 12
- 836
4 511
30
22
- 323
285
29
8 652
10 201





Maximum
Production
Capacity Aircraft
in Use Per Year Classes
M
20
135
5769
1906
826
12449
2493
5554
3159
458
7022

-
.G =
M =
T =
T
20
135
5769
632
1906
836
826"
515
30
22
12772
2493
5554
3444
29
458
7022
660
211
20
100
1000
500
1000
500
1300
1000
650
600
600
300
150
1000
500
500
Ai r Carrier Fleet
General Aviation
Mi 1 i tary Fleet
Total Engines in
11
10
9,10
5,6
10
12
10
12,5,6
6
5,6
10,12
10
11
10,12
12
10
10,11 ,12
4,6
4,6,12
Fleet
Use

Total
No.
In Use

..9.238
J393
15265
5554
1 1 824

0
v*>

-------
TABLE 7  (CONTINUED),
AIRCRAFT TURB

Engine
Class Manufacturer

TI-23 Pratt & Whitney D
TI-2** Vac.
TI-25
TI-26
TI-27
TI-28

TI-29 Rolls-Royce Ltd.
TI-30
TI-31
TI-32
TI-33
T 1-3*4
TI-35
TI-36 Bristol Eng. Div.
TI_ v; Rolls-Royce Ltd.
' ' J f
TI-38 Societe Turbomeca
TI-39 United Aircraft
Tl-^tO of Canada Ltd.
TI-M
-
TI-^2 Westinghouse
Population unknown.




Eng i ne
Fami 1 y
Model No.

i v . J 60
JT1.2A
T73
T3*4
PT2
ST9

Dart Mk 510
511+
520
529
532
5*42
Tyne 12
VIPER 522
601

ASTAZOU XIV
JT15
T7*4
PT6

J3^





Engine
Type

TJ
TJ
TJ
TP
TP
TS

TP
TP
TP
TP
TP
TP
TP
TJ
TJ

TP
TF
TS
TS

TJ




INE ENGINE CLASSIFICATI



ON SYSTEM

Thrust
or Type
Power Combustor

3300
3300
1*050
6000
6000
1500

1670
1850
1815
2100
2232
3025
5500
3360
3750

600
2200
715
715

3UOO
TOTAL




LB-T
LB-T
ESHP
ESHP
ESHP
ESHP

ESHP
ESHP
ESHP
ESHP
ESHP
ESHP
ESHP
LB-T
LB-T

ES:J,P
LB-T
ESHP
ESHP

LB-T

CN (8)
CN (8)
CN (8)
CN (8)
CN (8)
—

CN (7)
CN (7)
CN (7)
CN (7)
CN (7)
CN (7)
CN (10)
CA (1)
CA (1)
j
A
A
A
A

--
Tl ENGINES






A
-
8
-
-
-
-

32
72

-
1^8
1*48
36
2


-
_ .
-
26

-
A
G
M
T

No.
G
-
6*42
_
-
-
-

_
_
76
562

**6
16
I3*»
8

26
2
_
1672

-
= Air



Max imum
Product i on
Capacity Aircraft
in Use Per Year Classes
M
878
_
208
215

*

^
_
_
-
_
_
-
^


-
_
*432
T
878 220
650 no
208 200
215 60
30
_

32
72
76
562
1*48
19*4
52 - -
136
58

26
2
1*32 100
- 1698 50

*
Carr
= General
= Mi 1
i tary
= Total En

-
ier Fleet
Aviation Fleet
Fleet
gines in Use

10
*»,6, 1 0
10
9
9
--

5
5
6
5,6
5
5,6
5,6
U,6
6

6
6
5
5,11 ,12

10





No.
In U^:«







1951






—up


IS-

26


__. 	 	 _, _
? 1 3 ?.


TO:' 73
o
.r-


-------
                                                TABLE 7 (CONTINUED)
AIRCRAFT TURBINE ENGINE CLASSIFICATION SYSTEM

Engine
Class

T2-1
T2-2

T2-3

T2-5

T2-6
T2-7
T2-8
T2-9
T2-IO
T2-11
T2-12
T2-13
T2-14
T2-15

T2-16
T2-17
T2-18
T2-19
T2-20


Engine
Fami 1 y
Manufacturer . Model No.

All ison Div. GMC T4l
Curt iss-Wr ight Corp J65
.
General Electric J79
Co. CJ805
TF34
•
Pratt & Whitney Div. J52
Vac.-'- JT8D
J57
JT3C
J75
IT/i A
w 1 • »»
TF33
JT3D
TF30
JTF10

Rolls-Royce Ltd. AVON RA29
CONV/AY CO 12
CONV/AY C042
SPEY MK 51 1
MK 512


Engi ne
Type

TF
TJ

TJ
TJ.TF
TF

TJ
TF
TJ
TJ
TJ
TJ
TF
TF
TF
TF

TJ
TF
TF
TF
TF



Thrust
or
Power

15000
10500

17900
1 1 650 , 1
9000

11200
14500
18000
13500
26500
17500
21000
19000
13400
131*00

12600
17500
20370
1UOO
12550


LB-T
LB-T

LB-T
6100
LB-T

LB-T
LB-T
LB-T
LB-T
LB-T
LB-T
LB-T
LB-T
LB-T
LB-T

LB-T
LB-T
LB-T
LB-T
LB-T





Type
Combustor No. in Use

CN (10)
CA (1)
'
CN (10)
CN (10)
A

CN (9)
CN (9)
CN (8)
CN (8)
CN (8)
CN (8)
CN (8)
CN (8)
CN (8)
CN (8)
_
CN (8)
CN (10)
CN (10)
CN (10)
CN (10)

TOTAL T2 ENGINES
A
-
—
•
-
188
-

-
2831
-
160
-
376
-
2811
.
-

1*0
-
-
-
120

A = Ai
G M
-
- 137

- 10083
-
-

- 3733
310 -
- 8231
-
11*22
-
- 3707
28
- 1509
-

-
-
-
138 -
-

r Carrier
G = General Avi






M = Mi
1 i tary Fl
T
-
137

10083
188
-

3733
3191
8231
160
11*22
376
3707
2839
1509
-

1*0
-
-
138
120

Fleet
at ion
eet
. 	 T - Total Enoines in


Max imum
Product i on
Capacity Aircraft
Per Year Classes

500
100

1400
700
--

500
250
2000
1000
300
150
700
350
400
200

— _
__
__
_ _
--


Fleet

Use

10
10

10
3,4


10
i; £
8,10
3
10
3
9,10
3-9
10
--

4
3
3

'i.






Total
No.
In Use



M7



Toiyr










25168





298
35874


o
Baseline Engine
                                                                                                                        vn

-------
TAD I?  7 (CONTINUED)
AIRCRAFT TURB



Engi ne
Class

T3-1
T3-2
T3-3
T3-4
T3-5
T3-6
T3-7

T3-8
T3-9


Engine
Fami 1 y
Manufacturer Model No.

General Electric* JF39
Co. CF6
GE9
GE4
Pratt & Whitney Div. J58
Vac. JT11D
JT9D

Rolls-Royce Ltd. RB21 1
OLYMPUS 593


INE 7JIGINE CLASS IF




1 CAT ION SYSTEM






Thrust
Engine
Type

TF
TF
TF
TJ
TJ
TJ
TF

TF
TJ
or

Power

41100
40000
68600
30000
30000
47000

42000
37290

LB-T
LB-T

LB-T
LB-T
LB-T

LB-T
LB-T
TOTAL T3 ENGINES


Vv
RA«;P 1 i i


tc Fnoinp<;









Type
Combus tor

A
A
A
__
--
A

A
A
A =
G =
M ~
T =


No. in Use
A G M
- - 258
_
-
-
_
64 - -

— - _

Air Carrier
General Avi
Mi 1 itary Fl
T
258
-
- -
_
-
64

_


Max imum


Product ion
Capaci ty
Per Year

500
250
~ •"
500
250
500
^
^ —
** **
Ai rcraf t
Classes

8
2
"
10
--
2

2
1
Fleet


Total
No.
In Use




258



64

	 —
322
at ion F 1 eet
eet
Total Engines i

n Use





-------
                                           TABLE 8

                          AIRCRAFT  PISTON  ENGINE  CLASSIFICATION  SYSTEM'*


Engi ne
Class

P'l-1
PI-2
PI-3'
PI-*4
PI-5
PI-6
PI-7
PI -8
PI -9
PI-10
Pl-ll
PI-12
PI-13
P|-l*4
PI-15
PI-16
PI-17
PI-18
PI-19
PI-20
PI-21

PI-22
PI-23
PI-2*4
PI-25
PI-26
PI-27
PI-28

Engine
Fami ly
Manufacturer Model No.

Avco-Lycomi ng 0-235
Avco Corporation 0-290
0-320
0-360
0-*435
0-5*40
G0-*480
10-320
HIO-360
10-360
10-5*40
TIO-320
TIO-360
T 10-5*40
TIO-5*4l
TIO-5*47
IGSO-*480
IGSO-5*tO
VO-*435
V0-5*40
IVO-360

Continental Motors 0-200
DIV, Teledyne Corp. 0-300
0-*470
GO-300
w-670
10-360
I0-*470


Engine
Type

HO.NC
HO.NC
HO.NC
HO.NC
VO.NC
HO.NC
G.HO.NC
1 ,HO
1 ,HO
1 ,HO
I.HO
T, ,HO
T, ,HO
T, ,HO
T, ,HO
T, ,HO
I.G.S
I.G.S
VO.NC
VO.NC
1 ,VO

HO.NC
NO.NC
HO.NC
G,HO,NC
--
1 ,HO
1 ,HO
"
Thrust
or
Power

115 ESHP
1*40
160
180
260
260
280
160
180
200
300
160
200
310
380
--
3*40
380
260
305
180

100
1*45
2*40
1*45
--
210
260



No.
G
318
1302
20*400
7610
-
1622*4
263
3010
530
*458
2*430
87
12
2790
1150
258
10*»0
53
550
755
100

30600
2180
17050
1578
129
*429
*4960



in Use
M T
318
1302
20*400
7610
81*4 81*4
1622*4
*4l9 682
3010
530
*458
2*430
87
12
2790
1150
258
10*40
53
550
755
100

30600
2180
173 17223
1578
129
*429
*4960
Max imum
Product ion
Capac i ty
per year

1173
15
3700
2100
_ _
2700
306
__
__
__
«. _
_ _
__
__
200
• _
_ _
_ _
__
__
--

3187
1700
__
__
—
55*4
2000

Total
A i rcraf t i n
Classes Use

7
7
7
7
1 1
7,12
7,11,12
7
12
7
7
7
7
7-
7
7
7
7
12
12
12
-60573
7
7
7,11
7
7
7
7
Radial engines not included
G = General Aviation Fleet
M = Mi Iitary Fleet
T = Total Piston Fleet
                                                                                                               o
                                                                                                               —j

-------
                                        TABLE 8 (CONTINUEDI
PI-29
PI-30
Pl-31

PI-32
PI-33
PI-34*
PI-35
            Manufacturer
Franklin Engine CO
AIRCRAFT PISTON ENGINE C
Enqi ne
Fami 1 y
Model No.

10-520
TS10-520
GTSI 0-520
2A-I20
**A-235
6A-335
6A-350

Enq i ne
Type

1 ,HO
T.I.HO
G.T.I ,HO
HO.NC
HO.NC
HO.NC
HO.NC
LASSIFICATION SYSTEM
Thrust
or
Power

300
310
^35
50-90
65-80
200
230


No. in Use
G M
12930
3330
58
26
8
2*+2
1900
  T
12930
3330
  58

  26
  8
 2k2
1900
                                                                            Maximum
                                                                           Produc1i on
                                                                            Capac i'ty
                                                                            per year

                                                                           2600
Aircraft
Classes

7
7
7
7
7
7
7
                                                                                                    73^17
                                             TOTAL  PISTON  ENGINES
                                                                                                    21/6

                                                                                                    1^3,130
                                              HO = Horizontally  Opposed
                                              VO = Vertically  Opposed
                                              R  = Radia1
                                              NC = Normal Carburet ion
                                              I  = Fuel  Injection
                                              G  Geared  Propeller Drive
                                              T  = Turbo-Supercharged
                                              S  = Supercharged
                                                           G = General Aviation Fleet
                                                           M = Mi 1i tary Fleet
                                                           T = Tola 1  Pi ston  Fleet
                                                                                                              o
                                                                                                              CO

-------
                                                      TABLE  9

                             AIRCRAFT TURBINE AND  PISTON  ENGINE  CLASSIFICATION  SUMMARY
Total
Families
Class (Population)
Tl k2
(48773)
T2 20
(3587*0
T3 9
(322)
Air
Carrier
Fami 1 i es
(Population)
6*
dm)
10
(6576)
7
(64)
General
Aviation
Fami 1 ies
(Population)
16*
(6137)
2
(448)
0
(o)
Total
Civil
Aviation
Fami 1 ies
(Population)
22
(7251)
12
(7024)
7
(64)
Total
Mi 1 i tary
Fami 1 i es
(Populat i ori)
20
(41522)
8
(28850)
2
(258)
  TURBINE
   TOTAL
POPULATION
 84969
7754
  6585
  14339
 70630
••  Placement of engine  families  in these categories  is based upon majority of engine applications since some
   families are used  in both air carrier and general aviation categories.
  PISTON
   TOTAL
POPULATION
                        39
                      (136166)
136166
(*
(*
                         *)
                         *)
   34
(134760)
                    134760
   34
(134760)
                      134760
(1406)
                       1406
** Radial Engines not included
oWt Air  carrier  piston engines not  included
                                                                                            o
                                                                                            vo

-------
                                                                   no
                            TABLE  10
              EMISSION  CONTROL METHODS:  MODIFICATION OF
                         TURBINE ENGINES
 I.   Methods  applicable  to  existing  engines
           tl.   Combustion  chamber  redesign  (minor)  - Minor modifi-
                cation of combustion chamber and fuel nozzle  to achieve
                best  state-of-art emission performance.
           it2.   Combustion  chamber  redesign  (major)  - Major modifica-
                tion  of  combustion  chamber and  fuel  nozzle  in-
                corporating advanced fuel  injection  concepts  (car-
                buretion or prevaporization).
           t'3.   Fuel  drainage contro]  -  Modify  fuel  supply  system or
                fuel  drainage system to  eliminate  release of  drained
                fuel  to  environment.
           t4.   Divided  fuel  supply system - Provide independent  fuel
                supplies to subsets  of fuel  nozzles  to  allow  shut-down
                of one or more subsets during  low  power operation.
           t5.   Water injection -  Install water injection system  for
                short duration use  during maximum  power (take-off and
                climb-out)  operation.
           t6.   Modify compressor air bleed  rate  - Increase air
                bleed rate  from compressor at  low  power operation  to
                increase combustor  fuel-air  ratio.
I I.   Methods applicable  to  future engines
           t7.   Variable-geometry combustion chamber -  Use  of variable
                airflow  distribution to  provide independent control
                of combustion zone  fuel-air  ratio.
           t8.   Staged  injection combustor - Use  of  advanced  combustor
                design concept involving a series  of combustion zones
                with  independently-controlled  fuel  injection  in each
                zone.

-------
                                                                     11
                                TABLE  11
             EMISSION  CONTROL  METHODS:  MODIFICATION OF PISTON
                                  ENGINES
 1.   Methods  applicable  to  existing engines
           pi.   Simple air  injection  - Air  injected at controlled
                rate into each  engine exhaust  port.
           p2.   Thermal  reactors  - Air  injection  thermal  reactor
                installed in  place of, or downstream of,  exhaust
                manifold.
           p3.   Catalytic reactors for THC  arid CO control  - Air  in-
                jection  catalytic reactor  installed  in exhaust system.
                Operation with  lead-free or  low-lead fuel  required.
           p4.   Direct-Flame  Afterburner -  Thermal  reactor with  in-
                jection  of  air  and additional  fuel  installed  in ex-
                haust system.
           p5.   Water injection - Water  injected  into  intake  manifold
                with simultaneous reduction  in fuel  rate  to provide
                operation at  leaner fuel-air ratios.
           p6.   Positive crankcase ventilation.-  Current  PCV  system
                used with automotive  engines applied to aircraft
                engines.  Effective only  in  combination with  one of
                preceding control methods.
           p7.   Evaporative emission  controls  - A group of control
                methods  used  singly or  in combination  to  reduce
                evaporative losses from  the fuel  system.   Control
                methods  commonly include charcoal  absorbers and vapor
                traps in combination  with  relatively complex  valving
                and fuel flow systems.
I I.   Methods  applicable  to  future engines
           p8.   Engine  redesign - Coordinated  redesign of combustion
                chamber  geometry, compression  ratio, fuel  distribution
                system,  spark and valve  timing, fuel-air  ratio, and
                cylinder wall temperature to minimize emissions while
                maintaining operational reliability.

-------
                            TABLE 12A
             EMISSION CONTROL METHOD EFFECTIVENESS:
                  TURBINE ENGINE MOD IFI CAT IONS
Control Method                     tl  - Combustion Chamber Redesign (minor)
Best current emission rates assumed to be attainable through minor
comb us tor
Enqi ne
Class
Tl



T2



T3



Basis for
redesign (lb/1000
Pol lutant
CO
THC
.NOx
DP
CO
THC
NOx
DP
CO
THC
NOx
DP
estimates
Ib fuel)
Mode
Idle/Taxi
25
10
3
0.2
^5
10
2
0.2
50
10
3
0.1

Approach
5
1
7
0.5
6
1
6
0.5
3
1
10
0.1

Take-Off
2
0.2
11
0-5
1
0.1
12
0.5
0.5
0.1
i+0
0.1

It is assumed that emission rates for all  engines within a given
class can be reduced to common, optimum levels (on a lb/1000 Ib
fuel  basis) by minor combustor modifications.   These optimum
emission rates are based on the best performance reported for each
engine class, excluding extreme data points, as shown in Figures 1-4.

-------
                                                                  113

                            TABLE 12B
             EMISSION CONTROL METHOD EFFECTIVENESS:
                  TURBINE ENGINE MODIFICATIONS •
Control Method                     t2 - Combustion Chamber Redesign (major)
Emission Rate with Control  Method Installed (as  fraction of best  current
rate for
Enqi ne
Class
Tl
T2
Basis for
engine class)
Pol lutant
DP
DP
estimates
J
Mode
Idle/Taxi . Approach Take-Off
0.5 0,5 0.5
0.5 0.5 0.5

Estimates based on reports of carbureting fuel  injector performance
and reduction of smoke emission.   Concept is incorporated in some
Class T3 engines.  Estimates based on assumption that best emission
rate for Class Tl and T2 engines  is at visibility threshold at maximum
power.  Carburetion appears to reduce smoke level,  and presumably
particulate emissions, to approximately one-half that level (Refs 12 fl
13).

-------
                            TABLE 12C

             EMISSION CONTROL METHOD EFFECTIVENESS:
                  TURBINE ENGINE MODIFICATIONS
Control Method                     t3 - Fuel  Drainage Control

Emission Rate with Control  Method Installed (as fraction of best current
rate for engi
Engine
Class
Tl
T2
T3
Basis for est
ne class)
Pol lutant
THC
THC
THC
imates
Take-Off
Mode (Drainage
Idle/Taxi Approach Mode)
0
no change 0
0

Estimate based on the assumption that fuel drainage can be completely
eliminated by collecting drained fuel and returning to fuel  tank.

-------
                                                                  115

                            TABLE 12D
             EMISSION CONTROL METHOD EFFECTIVENESS:
                  TURBINE ENGINE MODIFICATIONS

Control Method                     t4 - Divided Fuel  Supply System
Emission Rate with Control  Method Installed (as fraction of best  current
rate for
Enqine
Class
Tl
Tl
T2
T2
T3
T3
Basis for
engine class)
Pol lutant
CO
THC
CO
THC
CO
THC
estimates
Mode
Idle/Taxi
0.25
0.25
0.25
0.25
0.25
0.25

Approach Take-Off


no change



Control method results in combustion zone fuel-air ratio similar
to that at approach condition.  Reduction in CO and THC from idle to
approach is approximately 90 per cent.   Effectiveness  reduced  by one
order because combustor is not operating at  a "wel1-designed condition.

-------
                                                                  116

                            TABLE 12E
             EMISSION CONTROL METHOD EFFECTIVENESS:
                  TURBINE ENGINE MODIFICATIONS
Control Method                     t5 - Water Injection
Emission Rate with Control Method Installed (as fraction of best current
rate for
Enqi ne
Class
Tl
T2
T3
engine class)
Pol lutant
NOx
NOx
NOx
Mode
Idle/Taxi Approach Take-Off
0.25
0.25
no change
0.25
Basis for estimates
Assumed that water injection used at take-off only and at a rate
equal to twice the fuel rate.  Also assumed that water is injected
into compressor or diffuser by system similar to those in current
use.  Effectjveness based upon published results with steam injection
(ftef  1*+).  Water injection assumed to be of equal effectiveness when
injected upstream of combustor.

-------
                                                                  117

                            TABLE 12F
             EMISSION CONTROL METHOD EFFECTIVENESS:
                  TURBINE ENGINE MODIFICATIONS
Control Method                     t6 - Modify Compressor.Air Bleed Rate
F.mission Rate with Control Method Installed (as fraction of best current
rate for
Enqi ne
Class
Tl
Tl
T2
T2
T3
T3
engine class)
Pol lutant
CO
THC
CO
THC
CO
THC
Mode
Idle/Taxi
0.5
0.5
0.5
0.5
0.5
0.5
Approach Take-Off



no change

Basis for estimates
Assumed that fraction of air which can be bled is small so that
engine operating point  is nearly unchanged.  Assumed that combustor
f/a varies inversely with air bleed rate, and that CO and THC
emissions at idle vary as:
                            (f/a)"3 -
                                          3
This relationship based upon data from NREC Report 113^-1 (Ref 1).   If
maximum air bleed rate is 20 per cent, CO and THC emission rates
are reduced by 50 per cent.

-------
                                                                       18
                                TABLE 12G
                 EMISSION CONTROL METHOD EFFECTIVENESS:
                      TURBINE ENGINE MODIFICATIONS
    Control  Method   .                  t7 - Variable-Geometry.Combust ion  Chamber
                                    or t8 - Staged Injection Combustor
    Emission Rate with Control  Method Installed (as fraction of best current
rate for engine class)
Enqine
Class
Tl



T2



T3



Basis for
Pol lutant
CO
THC
NOx
DP
CO
THC
NOx .
DP
CO
THC
NOx
DP
estimates :
Idle/Taxi
0.1
0.1
NC
0.5
0.1
0.1
NC
0.5
0.1
0, 1
NC
0.5

Mode
Approach
NC
NC
NC
0.5
NC
NC
NC
0.5
NC
NC
NC
0.5

Take-Off
NC
NC
0.5
0.5
NC
NC
0.5
0.5
NC
NC
0.5
0.5

a.  Assumed that combustor primary zone operates at a constant f/a
    equal to normal f/a at approach power condition (primary zone
    equivalence ratio = 0.6).   CO and THC emissions at idle reduced to
    levels corresponding to approach power,  or by 90 per cent.

b.  Combustor incorporates design characteristics which provide well-
    mixed combustion zone.  This feature and constant f/a operation
    combine to reduce NO emissions at full  power by 50 per cent (Ref 16)
    and particulate emissions by 50 per cent-at al.l power leve.ls as  in control
    method t2.

-------
                               TABLE 13
         CURRENT UNCONTROLLED EMISSION RATES - PISTON ENGINES
Pol lutant
CO
THC
NOx
(as N02)
(lb/
Idle
896
48
7
1000 Ib-fuel)
Mode
Taxi Approach
882 918
76 80
4 4
Take-Off
849
18
6
Basis for Estimates:
          Rates listed are average rates for nine engines measured
during aircraft operations (Ref 3).  Total hydrocarbon (THC) emission
rates have been increased by 50 per cent to account for crankcase blow-by
emissions.  Evaporative emissions are not included in these rates.

-------
                                                                     120
                                TABLE
                    EMISSION CONTROL EFFECTIVENESS:
                      PISTON ENGINE MODIFICATIONS
          Control  Method
Controlled Emission Rate"
 p] - Simple Air Injection

 p2 - Thermal Reactor

 p3 - Catalytic Reactor

 pk - Direct-Flame Afterburner

 p5 - Water  Injection

 p6 - Positive Crankcase Venti-
      lation

 p7 - Evaporative'Emission Control

 p8 - Engine Redesign
(fraction
CO

0.5
0.25
0.25
0.1
0.25
NC
NC
0.5
of uncontrol
THC
(exhaust .
only)
0.5
0.25
0.25
0.1
0.24
**
Vn.Wf
0.5
led rat
Lead

NC
NC
0.1
NC
NC
NC
NC
NC
 Basis for Estimates

          Review of published results..on effectiveness of automotive emis-

sion controls; in particular, References 17,  18,  and 19.
     Fractions listed are considered to be applicable to all operating modes.
     PCV would eliminate blow-by emissions when used in combination with pi,
     p2, p3, pk,  or p5.   Blow-by THC emission estimated to be equal to 30 per
     cent of uncontrolled exhaust emission.

     Evaporative  controls would reduce THC emissions due to evaporation from
     fuel supply.  Magnitude of uncontrolled emissions is unknown.

-------
                                                          TABLE  15

                            TOTAL AIRCRAFT TURBINE ENGINE  DEVELOPMENT  COST/TIHE  SAMPLE  CALCULATION
                                                                                                 Total  Total    No.
                                                                                                  Dev.   Dev.    of      Total
                                           Total  Total                                              &     &    Engine    Dev.
                                            Dev.   Dev.                                            Test   Test   Families   Cost
                                             &      &     Tool    Tool    Tool     Tool    Total  Total    &     &     in       Per
         No.    Control  Dev.  Dev.  Test  Test  Test   Test   Design  Design  Procure  Procure  Tool   Tool   Tool   Tool    Class    Class
Engine Engines  Method	Cost  Time  Cost  Time  Cost   Time    Cost    Time   .Cost     Time    Cost   Time   Cost   Time     T 2	T 2
$/FAM yrs.$/FAM yrs.$/FAM yrs.
JT8D
JT8D
JT8D
JT8D
JT8D
JT8D
3191 ti
3191 t2
3191 t3
3191 tk
3191 t$
3191 tt
360k 1-2
720k 2-3
360k 1-2
720k 2-3
200k 1
k
1080 1-2
360k 1-2 720k 2-4
720k 2-3 1 .44m 4-6
360k 1-2 720k 2-4
720 2- 3 l.44m 4-6
360k 1-2 560k 2-3
720k 2-3 1.8m 3-5
$/FAM yrs. $/FAM
10k
120k £-1 60k
20k
240k 1-3 A 120k
15k
I8ok 1-3 A 90k
20k
50k £-1 I0k
20k
240k 1-3 A 120k
yrs.
*-!
1-3 A
1-3 A
1-3 A
i"!
1-3 A
$/FAM
130k
I80k
260k
360k
I95k
270k
260k
360k
6ok
260k
360k
yrs. $/FAM yrs.
1-1 900k 2l-5 20
V
l-l! l.8m 5-7! 20
l-l! 990k 3-5! 20
l-l! l.8m 5-71 20
1-1 620k 21-4 20
l-l! 2.2m 4-6! 20
$
18"
36m
20m
36m
|2m
43-

-------
                                                      TABLE  16
Engine

 JT8D
 JT8D
 JT8D
 JT8D
 JT8D
 JT8D
TURBINE ENGINE DEVELOPMENT COST/T
CATEGORIES; AIR CARRIER,
Note:



Total
Develop-
ment and
Control Test and
Method Tool Cost
$/FAMILY
t, 900k
t2 1.8m
t3 990k
t^ 1.8m
t 620k
2.2m
Civil Aviat

Number .
of Ai r
Carrier
Engi ne
Fami 1 i es
in C lass
T2
_ _
10
10
10
10
10
10
ion Engines

Total
Deve lop-
ment Cost
for C lass
T2 Air
Carrier
Engi nes
$
9m
I8m
9-9m
18m
6.2m
22. Om
= Sum of


Number of
Genera 1
Avi a t i on
Fami 1 i es
i n C lass
T2

2
2
2
2
2
2
IME SAMPLE CALCULATION FOR SEPARATE
GENERAL AVIATION. MILITARY
Ai r Carrier
Total
Develop- .
ment Cost
for C lass
T2 Gen-
era 1
Aviation
Engi nes
$
l.8m
3.6m
2.0m
3.6m
1.2m
it.it"1
and Genera

Number of
Civi 1
Aviat ion
Engi ne
Fami 1 i es
i n C lass
T2

12
12
12
12
12
12
1 Avi at i on
Total
Deve lop-
ment Cost
for C lass
T2
Civi 1
Avia t i on
Engi nes
$
10. 8m
21. 6m
11. 9m
21. 6m
7.km
26. km
Engi nes

Number of
Mi 1 i tar y
Avia t i on
Engi ne
Fami lies
i n C lass
J12_

8
8
8
8
8
8

Total
Deve lop-
ment Cost
for C lass
T2
Military
Avia t ion
Engi nes
$
7-2m
1*4. it™
8.1m
li*.i*m
i*.6m
I6.6m

-------
                                                         TABLE 17

                          TOTAL AIRCRAFT PISTON ENGINE DEVELOPMENT  COST/TIME  SAMPLE  CALCULATION
Engine
Control  Dev.  Dev.  Test  Test  Total  Total   Tool    Tool    Tool     Tool    Total Total   Per    Total   No,  of   Total
 Method  Cost  Time  Cost  Time   Dev.   Dev.  Design  Design  Procure  Procure  Tool   Tool  Family   Time   Engines   Dev.
                              6-     &     Cost    Time    Cost     Time    Cost   Time   Total   Dev.  Families   Cost
                             Test   Test                                             One-     &       in     for
                             Cost   Time                                             Time    Test    Class   Class
                                                                                   Cost    Tool     PI      PI
                           yrs  $    yrs. $
                                  yrs.   $
                                       yrs.
$
yrs,
yrs.  $
yrs
Piston
Piston
Piston
Piston
Piston
Piston
Piston
P,
P2
P3
pi,
P5
P6
P
62k  i-l   170k i-
                            232
        6l
            i/3A 70
                                                 1-2
                       228k  1-2  350k  1-2  578k  2-k

                       2l6k  1-2  350k  1-2  566k  2-k

                       228k  1-2  350k  1-2  578k  2-k
                                 I70k i-l  231k   1-2

                                 95k  i-l  95k   i-l
                                           117
30*
120k
60k
120k
15k
5k
5k
i-i
i-l
i-i
i-i.
i-i
i i
V 2
i-i
IOK
30k
15k
30k
5k
5k
5k
i-i
i-l
i-i
i-l
i-i
i-i
i-i
ko
150k
75k
150k
20k
iok
,ok
i-l
1-2
i-l
1-2
i-l .
i-l
i-l
272
728k
6k} k
728k
25 lk
105k
I27k
li-3
3-6
2i-5
3-6
li-3
1-2
li-2i
35
35
35
35
35
35
35
9-5M
25.6N.
22. *4M
25.6M
8.8M
3.7M
k.S*

-------
                                                   TABLE 18

                       PISTON  ENGINE DEVELOPMENT COST/TIME SAMPLE CALCULATION FOR SEPARATE
                              CATEGORIES; AIR CARRIER. GENERAL AVIATION. MILITARY


                 Note:   Civil  Aviation Engines = Sum of Air Carrier and General  Aviation Engines






Control
Method
^ . —
pl
P2
P,
3
P4
Pr
5
P6
P.,



Total
Develop-
ment and
Test and
Tool Cost
$ /FAMILY
272k
728k
691k
728k
25lk
105k
12?k

Number
of Air
Carrier
Engi ne
Fami 1 i es
in Class
PI
_ _
0*
0
0
0
0
0
0

Total
Develop-
ment Cost
for Class
PI Air
Carrier
Engines
$
0
0
0
Q
0
0
0


Number of
General
Aviation
Fami 1 ies
in C lass
PI
— —
34
3*t
34
34
34
34
34
Total
Develop-
ment Cost
for C lass
PI
General
Avi at ion
Engi nes
$
' 9.3m
24. 8m
21.7
24. 8m
8.5m
3.6m
4.3m

Number of
Civil
Aviat ion
Engine
Fami 1 ies
i n C lass
PI
— —
34
34
34
34
34
34
34

Total
Develop-
ment Cost
for C lass
PI Civi 1
Aviat ion
Engi nes
$
9.3m
24. 8m
21.7k
24. 8m
8.5m •
3.6m
4.3m

Number of
Mi I i tary
Aviat ion
Engine
Fami 1 i es
in C lass
PI
V •
1
1
1
I
1
1
1
Total
Develop-
ment Cost
for Class
PI
Mi li tary
Aviat i on
Engi nes
$
272k
728k
641 k
728k
251k
-05k
127k
Air carrier piston engines  not  included.

-------
                                                       TABLE 19
        Control
Enqi ne  Method
JT8D
JT8D •
JT8D
JT80
JT8D
JT80
TOTAL AIRCRAFT TURB
Lost
Serv ice
Life
Cost/
Enq i ne
$/Eng
2500
2500
500
2500
0
0
Add.
1 ns tal-
lat ion
Cost/
Enqi ne
$/Eng
2000
*4000
1000
2000
2000
1500
10 Years
Total
Add.
Instal-
lation
Cos-t/
Enqi ne
$/Eng
8000
16000
itOOO
8000
8000
6000
INE ENGINE
Cont inu-
inq Add.
Cost/
Enq i ne/
Year
$/Eng/Yr
2500
k2kO
0
0
760
0
IMPLEMENTATION COST/TIME SAMPLE CALCULATION
10 Years
Cont i nu-
i nq Add.
Cost/
Enq i ne
$/Eng
25000
i*2*+00
0
0
7600
0
10 Years
Total
Imple-
ment
Cost/
Enq i ne
$/Eng
35500
60900
i*500
10500
15600
6000
Total
No. of
Enqi nes
in Class
."T 2
3587*4
3587*4
3587*4
3587*4
3587*4
3587*4
10 Years
Total
Imp le-
ment
Cost for
. Class T2
Enq i nes
$xlo'S
1275
2180
161.
376
560
215
Total
T ime
Be tv/een
Over-
hau 1 s
(TBO)
Yrs.
2 1/2
2 1/2
2 1/2
2 1/2
2 1/2
2 1/2
                                                                                                       Imp Ie-
                                                                                                       ment
        Imp 1e-
        ment
Start   Finish
Date
1977
1979
1977
1979
1976
1978
Date
1979
1983
1980
1982
1978
1981
                                                                                                                K>
                                                                                                                NJ1

-------
                                                      TABLE 20
Engi ne

 JT80
 JT8D
 JT8D
 JT8D
 JT8D
 JT8D

TURBI
NE ENGINE
IMPLEMENT AT
CATEGORIES: AIR






Control
Method

--
t,
t2
t3
t^
t5
1 £
Note


10 Years
Total Im-
plementa- .
tion Cost/
Engi ne

$/ENG
. 35,500
60,900
^,500
10,500
15,600
6,000 '
ION COST/TIME SAMPLE CALCULATION
CARRIER, GENERAL AVIAT
FOR SEPARATE
ION, MILITARY
Civil Engines - Sum of Air Carrier and General Aviation Engines

Number
of Ai r
Carr i er
Engi nes
in Class
T2

--
6,576
6,576-
6,576
6,576
6,576
6,576
Total
Implement
Cost for
Class T2
Air
Carr i er
Engi nes
..
$x!0b
233
koo
30
69
103
39

Number of
General
Aviation
Engi nes
in C lass
. T2

--
M»8
kkB
kkB
kkB
kkB
kkB
Total
Implement
Cost for
Class T2
General
Aviat i on
Engi nes
-6
$x!0b
16
27
2
5
7
3

Number of
Ci vi 1
Aviat ion
Engi nes
i n C lass
T2

--
7,02k
7,02k
7,02k
7,02k
7,02k
7,02k
Total
Impl ement
Cost for .
Class T2
Civil
Aviat ion
Enqi nes
-6
$xlO
250
i*28
32
7k"
110
1*2

Number of
Mi 1 i tary
Aviat ion
Engi nes
in C lass
T2


28,850
28,850
28,850
28,650
28,850
28,850
Total
Impl ement
Cost for
Class T2
Mi Li tary
Aviat i on
Engi nes
-6
$xlO D
1,025
1,752
129
302
*450
173

-------
TABLE 21
TOTAL AIRCRAFT PISTON ENGINE IMPLEMENTATION COST/TIME SAMPLE CALCULATI






Enqi ne

- —
Piston
Piston
Piston
Piston
Piston
Piston
Piston





Control
Method

--
P.
pi
p
P;

P6
P?


Lost
Service
Life
Cost/
Enq ine

$/Eng
25
25
25
25
0
0
0


Add.
Instal-
lat ion
Cost/
Enqine

$/Eng
U50
850
825
850
300
150
500
10 Years
Total
Add.
Instal-
lation
Cost/
Enqine

$/Eng
900
1700
1650
1700
600
200
1000




10 Years
Cont i nu-
inq Add.
Cost/
Enqi ne/
Year

$/Eng/Yr
30

230
1^2
0
50
100
10 Years
Cont i nu-
inq Add.
Cost/
Enqi ne

$/Eng
300
1^20
2300
Ht20
0
500
1000
Total
Imple-
ment
Cost/
Enqine

$/Eng
1225
31^5
3975
31**5
600
700
2000
Total
No. of
Enqi nes
in C lass
PI
•
— —
136,166
136,166
136,166
136,166
136,166
136,166
136,166
10 Years
Total
Imp le-
ment
Cost for
Class PI
Enqi nes
" 6
$x!0°
167
i+30
5^2
1+30
82
96
272
ON

Total
T ime
Between
Over-
hauls
(TBO)

Yrs.
5
5
5
5
5
5
5




Imple-
ment
Start
Date

— -
1975
1978
1977
1978
1975
197*»
197**




Imple-
ment
Finish
Date

— —
1980
1983
1982
1983
1980
1979
1979

-------
                               TABLE 22

PISTON ENGINE  IMPLEMENTATION COST/TIME SAMPLE CALCULATION FOR SEPARATE
         CATEGORIES:  AIR CARRIER. GENERAL AVIATION.  MILITARY


.Note:  Civil Engines = Sum of Air Carrier and General Aviation Engines





Control
Method
--
pl
P2
P3
pk
P5
P6
P7


10 Years .
Total Im-
plementa-
tion Cost/
Engi ne
$/ENG
1,225
3,1**5
3,975
3,1**5
600
700
2,000

Number
of Air
Carrier
Engi nes
i n C lass
PI
--
0
0
0
0
0
0
0
Total
Implement
Cost for
Class PI
Air
Carrier
Engi nes
$xlO~6
0
• 0
0
0
0
0
0

Number of
Genera 1
Aviat ion
Engi nes
in C lass
PI
--
13**, 760
13**, 760
13**, 760
13**, 760
13**, 760
13**, 760
13**, 760
Total
Implement
Cost for
Class PI
General
Aviat i on
Engi nes
$xlO
165
**2**
536
^2^
81
95.
270

Number of
Civil
Aviat ion
Engi nes
i n C lass
PI
.
13**, 760
13**, 760
13**, 760
13**, 760
13**, 760
13**, 760
1 3*», 760
Total
Imp lement
Cost for
Class PI
Civil
Aviat ion
Enqi nes
$xlO~6
165
k2k
536
k2k
81
95
270

Number of
Mi 1 i tary
Aviation
Engi nes
i n C lass
PI
--
1 ,**06
1,**06
1 ,**06
1 ,*»06-
1 ,**06
l,**06
1,**06
Total
Impl ement
Cost for
Class PI
Mi 1 i tary
Avia t i on
Engi nes
$xlO~6
1.7
k.k
5.6
*t.**
0.8
1.0
2.8
                                                                                        OO

-------
                                               TABLE  23
                            TURBINE ENGINE COST SCALING PARAMETER SUMMARY


Engine SFC OPR W T(P)
Ib/HP-HR P2/P](lbs) Ibs(ESHP)
T53 0.56 8 561 igoo
*JT8D 0.63 18 3309 15500
TF39 0.58 25-7 7311 141100
10 Year 10 Year
Total Total
Imple- Imple-
ment ment
Cost/ Cost/
SFCxOPR 2W/T P P/P... Engine /T" /f77%~ Engine
$/ENG. -tfTbs " $/EMG.
i*.i»8 0.59 5.07 0.1*3 15250 1*3.6 0.35 121400
11.35 0.1*3 11.78 1.00 35500 125 1. 00 35500
11*. 95 0.36 15.31 1.30 146200 205 1.64 58300
P = Technical Scaling Parameter = J_(SFCxOPR)+ 2W 1
T J
SFC = Specif!
OPR = Over-AI
W = Engine
T = Engine
c Fuel Consumption
1 Pressure Rat io
Dry Weight
Thrust
Base Iine Engine

-------
                                     130
TABLE 2k
FINAL COST/TIME RESULTS FOR TOTAL TURBINE
Cost
Seal i ng
Factor
0.35
0.35
0.35
0.35
0.35
0.35
1.00
1.00
1.00
1.00
1.00
1.00
1.6it
1.64 .
1.64
1.64
1.64
1.64







Engine
Class
Tl
T 1
T 1
T 1
T 1
Tl
T2
T2
T2
T2
T2
T2
T3
T3
T3
T3
T3
T3
2T =T1
2T =T1
ST =TI
£T =TI
£T =TI
£T =T1

Baseline Control
Engine Method
T53 t,
T53 t2
T53 t3
T53 t^
T53 t$
T53 t&
JT8D t]
JT8D t2
JT8D t
JT8D . t^
JT8D t
JT8D t6
TF39 t,
TF39 t2
TF39 t3
• TF39 t^
TF39 t5
TF39 t6
+ T2 + T3 t]
+ T2 + T3 C2
+ T2 + T3 t3
+ T2 + T3 ^
+ T2 + T3 t5
+ T2 + T3 . t6

Total
Fami 1 ies
w
It 2
[i o
42
42
42
20
20
20
20
20
20
9
9
9
9
9
9
71
71
71 '
71
71
" 71
ENGINE POPULATION

Total
Engines
48,773
48,773
48,773
48,773
48,773
48,773
35,874
35,874
35,874
35,874
35,874
35,874
322
322
322
322
322
322
84,969
84,969'.-
84,969
84,969
84,969
84,969-
Total
Dev. and
Implement
Cost, $
643- OM
1116. OM
120. OM
257. OM
295. OM
196. OM
1293.0M
2226. OM
181. OM
412. OM
572. OM
258. OM
26. 8M
48. 4M
11. 3M
21.7M
13. 9M
23. OM
1963M '
3390M •
312M
691M
881M
477M .
Total
Dev. and
Implement
Time, yrs
5-71
71-10
51-8
71-10
5-61
61-9
5-71
71-10
51-8
71-10
5-61
61-9
5-71
71-10
51-8
71-10
5-61
61-9
5-71
71-10
51-8
71-10.
5-61
61-9

-------
TABLE 25
FINAL COST /TIME RESULTS
FOR TURBINE ENGINE POPULATION BY SEPARATE
CATEGORIES: AIR CARRIER, GENERAL AVIATION,

Engine Control
Class Method
--
Tl tj
Tl t2
tj
Tl tfy
T, t5
Tl '6
T2 "t,
T2 t2
T2 t3
T2 tk
T2 t
T2 t6
T3 t,
T3 t2
T3 t3
T3 t.
Note; Ci
Cost
Seal i ng
Factor
--
0.35
0.35
0.35
0.35
0.35
0.35
1.00
1.00
1.00
1.00
1.00
1.00
1.64
1.64
1.64
1.64
vi 1 Engi ne = Sum
. Development
Cost Per
Fami ly
$/FAMxlO
0.90
K80
0.99
1.80
0.62
2.20
0.90
1.80
0.99
.1.80
0.62
2.20
0.90
1.80
0.99
1.80
of Air Carrier and Genera
Impl ement
Cost Per
Engi ne
$/ENGxl03
12.4
21.3
1.6
3-7
5-5
2.1
35-5
69-9
^•5
10.5
15.6
6.0
58.3
100.0
7.4
17-2
Air
Carrier
Total
Cost
$x!06
19-2
34.5
7-7
14.9
9.8
15-5
243.0
418.0
39-5
87-0
108.7
61.5
10.0
19.0
7-4
13-7
MILITARY


1 Aviation Engines
Genera 1
Aviat ion
Total
Cost
$xl66
90.5
159.3
25.6
51-5
43.6
48. 1
17.8
3.1.0
4.0
8.3
8.2
7-1
0.0
0.0
0.0
0.0
Civil
A vi at ion
Total
Cost
$xl66
109.7
193.8
33.5
66.4
53.4
63.6 -
259-8
449.6
43.5
95.3
116.9
68.6
10.0
19.0
7.4
13.7
Mi 1 i tary
Avi at i on
Total
Cost
$xl66
533-0
921.0
87-0
190.0
240.0
131.0
1032.2
1774.4
137-9
317.4
454.9
190.6
16.8
29-4
3-9
8.0

-------
                      TABLE 25 (CONTINUED)
FINAL COST/TIME RESULTS FOR TURBINE ENGINE POPULATION BY SEPARATE
CATEGORIES: AIR CARRIER, GENERAL AVIATION,
Engine Control
Class Method
T3 t,.
T3 t6
ET=TI+T2 +T3 t.
ET=TI + T2 4T3 t2
ET=TI+1 2 +T3 t_
ET=TI+T2 +T3 t^
ET=TI+T2 +T3 t
ET+TI+T2 +T3 t.
Cost Development
Seal ing Cost Per
Factor Fami ly
1.6** 0.62
\.6k 2.20
__ •
.
__
—
—
__
Implement
Cost Per
Engi ne
25.6
9.9
—
--
--
--
--
--
Air
Carr i er
Total
Cost
5-9
16.0
272.0
^72.0
5^.0
116.0
125.0
93.0
MILITARY
Genera 1
Aviation
Total
Cost
0.0
0.0 .
108.0
192.0
29.0
61.0
52.0
55.0
Civi 1
Aviation
Total
Cost
5-9
16.0
380.0
66*t.O
83.0
177.0
177.0
1^8.0
Mi 1 i tary
Aviat i on
Total
Cost
7.8
7.0
1583.0
2726.0
229.0
51^.0
70k. 0
329.0

-------
                                      133
TABLE 26

FINAL
COST/TIME RESULTS FOR TOTAL PISTON ENGINE
POPULATION .

Cost
Seal i ng
Factor

1.00

1.00

1.00

1,00

1.00

1.00

1.00


Engi ne
Class

PI

PI

PI

PI

PI

PI

PI
-

Baseline Control
Engine Method
Aircraft
Piston P.
Aircraft
P i s ton ?2
Ai rcraft
Piston P.
Ai rcraft
Piston P.
Aircraft
Piston P_
Aircraf t
P I s ton P.
Aircraft
Piston ?7


Total
Fam i 1 i es

35

35

35

35

35

35

35


Total
Engines

136,166

136,166

136,166

136,166

136,166

136,166

136,166
Total
Dev. and
Implement
Cost, $

176. 5M

453. 6M

564. 4M

453. 6M

90. 8M

98. 7M

276. 5M
Total
Oev. and
Implement
Time, yrs

61-8

8-11

71-10

8-11

61-8

6-7

61-71

-------
TABLE 27
FINAL COST /TIME RESULTS FOR PISTON ENGINE POPULATION BY SEPARATE
CATEGORIES: AIR CARRIER, GENERAL AVIATION,
Note: Civil Engine = Sum


Engi ne
Class
--
PI
PI
PI
PI
PI
PI
PI


Control
Method
--
P]
P2
P3
pit
P5
P6
P7

Cost
Seal i ng
Factor
--
1.00
1.00
1.00
1.00
1.00
1.00
1.00

. Development
Cost Per
Fami ly
$/FAMxl06
0.27
0.73
0.6it
. 0.73
0.25
0.11
0.13
of Air Carrier and Genera

Implement
Cost Per
Engi ne
$/ENGxl63
1.23
3.15
3.98
3.15
0.60
0.70
2.00
Air
Carr i er
Total
Cost
$x!06
0.0
0.0
0.0
0.0
0.0
0.0
0.0
MILITARY


1 Aviation Engines
General
Aviat ion
Total
Cost
$xl66
17**. 5
itit8.it
556.8
Mi8.7
89.7
97.6
273-3
Civi 1
Avi at ion
Total
Cost
$xl66
17^.5
itit3.it
556.8
itit8.it
89.7
97-6
273.3
Mi 1 i tary
Aviat ion
Total
Cost
$xl66
2.0
5.2
6.3
5.2
1. 1
1. 1
3.0

-------
                                             TABLE 28

           IMPLEMENTATION COST/TIME SAMPLE CALCULATION FOR "PRODUCTION"  TURBINE  ENGINES
Enq i ne
JT8D
JT8D
JT8D
JT8D
JT8D
JT8D
Additional
Insta 1 lat ion
Control Cost Per'
Method Enqine
$/Eng x lo"3
t, 1.0
t2 3.0
t3 0.5
t|, 1-5
t 1.8
t, 1.0
OF EX
10 Years
Total
Add! t ional
1 nsta 1 lat i on
Cost Per
Enqine
$/Eng x 10"3
12.0
2.0
6.0
7.2
ISTING DESIGN
Cont i nu i nq
Add! t iona 1
Cost/Engine/
Year
$/Eng/Yr x
2.5
0
0
0.76
0
10 Years
Cont i nu i nq
Additional
Cost Per
Enqine
$/Eng x 103
25.0
0
0
3.0
0
10 Years
Total
Implementa t ion
Cost Per
Enqi ne
$/Eng x 103
29.0
2.0
6.0
10.2
Effect i ve
Product ion ,
Start Date
1977
1979
1977
1979
1976
1978
This date assumes the control  system development  effort  is  initiated  1/1/72  and  that  the  maximum
development, test ing,  and tooling time is required,  as tabulated in Table 15-

-------
                                              TABLE 29
             IMPLEMENTATION COST/TIME SAMPLE CALCULATION FOR "PRODUCTION" PISTON ENGINES
OF EXISTING DESIGN





Enq i ne

Pi ston
Piston
Pi ston
Piston
Piston
Piston
Piston



Add! t iona 1
1 nsta 1 la t ion
Control Cost Per-
Method Enqine
$/Eng x 103
Pj 0.200
P2 0.500
P3 0.^*75
P^ 0.500
P5 0.150
P6 0.075
P., 0.100
7
10 Years
Total
Add i t i ona 1
Insta 1 lat ion
Cost Per
Enq i ne
$/Eng x 103
0.1+00
1.000
0.950
1.000
0.300
o. 150
0.200



Cont i nu i nq
Add i t iona 1
Cost/Enqi ne/
. Year
$/Eng^Yr x
0.030
0. 11+2
0.230
0. 1i»2
0
0.050
0.100


10 Years
Cont i nu i nq
Add i t iona 1
Cost Per
Enqi ne
$/Eng x 103
0.30
1.1+2
2.30
1.1+2
0
0.50
1.00


10 Years
Tota 1
Imp 1 emen ta t i on
Cost Per
Enqi ne
$/Eng x 10 3
0.70
2.1+2
3.25
2.^42
0.30
0.65
1.20

                                                                                            Effect i ve
                                                                                           Product i on,
                                                                                           Start Date'
                                                                                              1975

                                                                                              1978

                                                                                              1977

                                                                                              1978

                                                                                              1975
This date assumes the control  system development  effort  is  initiated 1/1/72 and that  the maximum
development,  testing, and tooling time is  required,  as  tabulated in Table .17-

-------
                                                                 137
                            TABLE  30




IMPLEMENTATION  COST/TIME  FINAL  RESULTS  FOR  "PRODUCTION"  ENGINES-
Enqi ne
Class

Tl
Tl
Tl
Tl
Tl
Tl
T2
T2
T2
T2
T2
T2
T3
T3
T3
T3
T3
T3
PI
PI
PI
PI
PI
PI
PI
TURBINE
Control
Method
t,
tz
t3
tk
t5
t6
t,
t2
'3
|5
t]
t2
t3'
t^
'5
pl
P2
P3
Pi
4
P5
P6
P7
AND PISTON
Seal i nq
Factor

0.35
Q.35
0.35
0.35
0.35
0.35
1.00
1.00
1.00
1.00
1.00
1.00
1.61*
1.61*
1.61*
1.61*
\'.ll
1.00
1.00
1.00
1.00
1.00
1.00
1.00
ENGINES OF. EXISTING
10 Year
Total
Implementat ion
Cost Per
Enq i ne
$/Eng
101,50
19,000
700
2,100
3,570
1 ,1*00
29,000
51*, 1*00
2,000
6,000
10,200
1*7,600
89,200
3,280
9,81*0
16,700
6,560
700
2,1*20
3,250
2,1*20
300
650
1,200
DESIGN
Implementat ion
Start Date

1977
'1979
1977
1979
1976
1978
1977
1979
1977
1979
1976
1978
1977
1979
1977
1979
1976
1978
1975
1978
1977
1978
1975
1971*
1971*

-------
                                                                         138
                                    TABLE 31
COST/TIME

Item Unit
Design Cost $
Prototype
Hardware Cost $
Testing Cost $
Cost of
1 ncorporation of
Prototype Design
into Demonstrator
Engine $
Total
Demonstrator Engine
Development Cost $
Prototype
Development Time Yrs
Fraction of
Development Cost
Attributable to
Emission Control %
Fraction of
Development Time
Attributable to
Emission Control ' %
RESULTS FOR FUTURE TURBINE ENGINES

New Combustor .. . . , . .
,. Variable Geometry
_ . T Combustor
Current Type
150K 300K
180K 280K
620K 740K

850K 1000K

1800K 2240K
2.0 3.5


0.0 34


0.0 43

Staged Injection
Combustor
550K
360K
850K

900K

' 2660K
5.0


47


60
Fraction of Engine
Purchase Price
from Combustor
k.S
8.5
7.0

-------
                                                                           139
                                        TABLE 32
Alrcraft
 Class
   2
   3
   4
   5
   6
Averaqe
Number
of
Enqi nes
£e_r
Ai rcraf t
4
4
2.6
2.5
2.1
REDUCTION IN EMISSION
INCREASE
CO

Uncontrol led
Idle Emissions
Per Enqine Of
Grams Per Hour
427000
68600
26000
5800
26700
FACTORS FOR
IN IDLE POWER
Pol
100 PER CENT
lutant

Hydrocarbons
Control led
Emiss ions
As Per Cent
Uncontrol led
Emissions
58
62
62
20
59
Uncontrol led
Idle Emissions
Per Enqine
Grams Per Hour
10500
30800
3540
1900
3130
Control led
Emissi ons
As Per Cent
. Of Uncontrol led
Emi ss i ons
108
91
71
30
61

-------
                                                          \ko
                       TABLE 33
REDUCTION IN TAXI AND IDLE EMISSIONS RESULTING FROM THE
USE OF THE MINIMUM NUMBER OF ENGINES FOR TAXIING
Number
Aircraft of
Class Engines
2 4 to 2
3 4 to 2
4 3 to 2
2 to 2
2.6 to 2 mean
5 4 to 2
2 to 2
2.5 to 2 mean
6 4 to 2
2 to 2
2.1 to 2 mean
2 4 to 1
3 4 to 1
4 3 to 1
2 to 1
2.6 to 1 mean
5 4 to 1
2 to 1
2.5 to 1 mean
6 4 to 1
2 to 1
2.1 to 1 mean
Control
Rate as
led Emission
a Per Cent of
Uncontrol led
Emiss
CO
29
31
42
62
48
10
20
16
30
59
56
15
15
21
31
24
5
10
8
15
30
28
ion Rate
Hydrocarbons
54
45
48
71
55
15
30
24
30
61
58
27
22
24
35
27
7
15
12
15
30
29

-------
TABLE 34
TOTAL AIRCRAFT
Pol lutant

CO
NOx
so2
particulates
lead
hydrocarbons
reactive
hydrocarbons
aldehydes
Approach
704
302
163
175
0.0205
843
6.36
111
Landing

288
1.09
2.81
1.25
0.0042V
117
0.253
3.81
EMISSI
Taxi

8720
33.2
67.6
37.7
0.153
3520
6.06
108
ONS FOR 1970
Idle &
Shut-
Oown
grams
32k
0.678
2.41
10.7
0.00106 0
141
0.127
4.38
AT LOS ANGELES INTERNATIONAL
Main-
tenance
x 10'6
864
50.5
22.5
26.2
.0241
426
0.581
13.2
Start-up
& Idle

728
2.27
5.63
3.12
0.0127
293
0.505
9.01
Delay
at
Runway
1360
5.16
10.5
5.87
0.0238
548
0.9*O
16.8
AIRPORT
Take-
Off

87.1
246
400
103
0.0155
29.8
4.49
2.87
C 1 imb-
Out

115
293
444
118
0.0502
39.1
6.10
3.22
Fuel
Dump'
ing
0
0
0
93. ^
0
93. ^
17.2
0

-------
                      TABLE 35




PERCENTAGE REDUCTION IN TOTAL AIRCRAFT EMISSIONS DUE TO
AVOIDING RUNWAY DELAYS AT LOS ANGELES INTERNATIONAL AIRPORT
Pol lutant
CO
NOx
so2
participates
lead
hydrocarbons
reactive
hydrocarbons
aldehydes
Delay
Mode
Emissions
Grams Per
Year x 1Q-&
1360
5.16
10.5
5.8?
0.0238
5^8
0.9^3
16.8
Total
Emissions
Grams Per
Year x 10'°
13200
93^
1120
57^
0.305
6060
U2.7
273
Controlled
Emi ss ions
Per Cent
Of Un-
Control led
Emiss ions
90
99.5
99
99
93
91
98

-------
                                                                  143
                              TABLE 36
Ai rcraf t
Class 1
Class 2
Class 3
Class 4
Class 5
Class 6
Diesel
Fuel led
Vehicles
CO
1*5900
9770
15700
3870
829
3210

EMISSIONS FOR TAXI MODE
Reactive
Aide- Hydro-
NO S0» hydes carbons
612' 	 1160 	
321 145 39.5 2k]
15.1 115 222 	
3k. 2 4.13 3.27 	
189 	
18.1 87.9 25.0 	

Total
Hydror
carbons
200
2410
7040
526
271
376

Partic-
Lead ulates
	 0
236
— - 46.5
	 48.5
	 20.1
	 3.87

Tractor
439  1030    91.1    6.13
51.1
20.4

-------
                      TABLE 37




PERCENTAGE REDUCTION IN TOTAL AIRCRAFT EMISSIONS DUE TO
ELIMINATION
Pol lutant
CO
NOx
so2
ti culates
lead
Irocarbons
eactive
Irocarbons
lehydes
OF THE TAXI MODE AT LOS
Delay
Mode
Emissions
Grams Per
Year x 10 ~°
8720
33.2
67.6
37.7
0.153
3520
6.06
108
ANGELES INTERNATI
Total
Emiss i ons
Grams Per
Year x 10 ~6
13200
93^
1120
574
0.305
6060
42.7
273
ONAL AIRPORT
Control led
Emi ss ions
Per Cent
Of Un-
Control led
Emi ssions
9b
94
93
50
42
86
60

-------
Total
                                                             145
                         TABLE  38

             POLLUTANTS FROM AUXILIARY POWER UNIT


                For Each  Mode  in  Grams
Mode
Taxi
Park
Taxi
Ascent
CO
19.7
157
39.3
19.7
NOx
40.5
324
81.1
40.5
Hydrocarbons
27.U
219
5^.7
27.4
Participates
6.84
54.7
13.7
6.84

 236
486
328
82.1
       For Los Angeles International  Airport  For  1970
                      ™Hydrocarbons"
Em!ss ions
 Without
 APU as a
 Per Cent
  of Un-
Controlled
Emissions
          NOx
                           Participates
99.5
             98.5
                 96

-------
                        TABLE 39

     COMPARATIVE REDUCTIONS RESULTING FROM CONTROL
  METHODS APPLIED TO LOS ANGELES INTERNATIONAL AIRPORT


                              Controlled Emissions as Per Cent
                                  of Uncontrolled Emissions
Control Method                      C0_       Hydrocarbons

1.  Increase engine idle rpm        71            93

2.  Increase idle rpm and use
    minimal engines for taxi:

    a.  two engines                 53            66

    b.  single engine               39            51

3.  Eliminate delays at gate
    and runway                      90            91

k.  Transport passengers be-
    tween terminal  and air-
    craft                          100           100

5.  Tow aircraft to avoid taxi
    emissions                       3^            42

6.  Avoid use of aircraft auxi-
    liary power units             99.5          98.5

7.  Control emptying of fuel
    drainage reservoirs            100          98.4

-------
                                                   TABLE **0

                              BASIS  FOR  ESTIMATING COSTS OF GROUND OPERATION CHANGES
                                     AT  LOS ANGELES  INTERNATIONAL AIRPORT
  Control
  Method

Increase
Idle
Speed

Minimal En-
gi ne Taxi :
2 Engines
1 Engine
Control led
Gate
Departure

Passenger
Transport


Ai rcraft
Towi ng
Ground-Based
APU
 Fuel Drainage
 Equ i pment
     Land
     Cost
 Construe t ion
     Cost
  Equipment
    Cost
   Automati ng
      Cost
18 Acres at
$50K per Acre


90 Acres at
$50K per Acre
18 Acres at
$500K per Acre

90 Acres at
$500 per Acre
IBM 360/65
75 Vehicles
$200K per
Vehicle

25 New Ve-
hicles $30K
per Vehicle


37 Ai r Supply
at $20K
37 Electrical
at $15K

75 Devices at
$500
25 Man-Years
$60K per Man-Year


3 Man-Years
$60K per Man-Year


8 Man-Years
$60K per Man-Year
         Per Annum
      Operating Cost
          Change

Fuel:  600 Ib per Engine-
Hour at $O.OVlb, 360K
Engine-Hours
Save 90K Engine-Hours
Add 200 Ib per Hour
Fuel for 270K Engine-
Hours

Save 227K Engine-Hours
Add 600 Ib per Hour
Fuel for 133K Engine-
Hours
Save 1200 lb-Fue.1 per
Engine-Hour frOK Engine-
Hours

Save 180K Engine-Hours
Spend $frOK Labor, $20K
Fuel per Vehicle

Save 360K Engine-Hours
Spend $UOK Labor, $20K
Fuel per Vehicle
Spend 150K Crew Hours

Spend $20K Fuel  per
Vehicle
                                                                        Add 75 Man-Years

-------
                                                     TABLE
Control Land
Method Cost
Increase
Idle
Speed
Minimal En-
gi ne Taxi :
2 Engines
1 Engine
Controlled $900K
Gate
Departure
Passenger $**500K
Transport
Aircraft
Towi ng
Ground-Based
APU
Fuel Drainage
IMPLEMENTATION COST AND
LOS ANGELES 1
Construction Equipment
Cost Cost
~ . --


__
..
$9000K $^OOOK

$^5,OOOK $15,OOOK
$750K
$1295K
$38K
TIME FOR OPERATIONS CHANGES
NTERNATIONAL AIRPORT
Total
Automating Initial
Cost Cost
$0


$0
$0
$1500K $l5,i+OOK

$180K $6^,680K
$^80K $1230K
$1295K
$38K
AT
Per Annum
Change in Cost
of Operation
$8500K


^$3000K
-$7500
-$1560

-$^000
to $5000K
+$** 17, ooo
$1500K
$3000K
T ime
Requi red
Negl i gible


b Months
I Year
5 Years

2.5 Years
1 Year
6 Months
6 Months
Equi pment
                                                                                                               CO

-------
                                              TABLE 42

                                 FACTORS AFFECTING FEASIBILITY  OF
                      OPERATING CHANGES AT LOS ANGELES INTERNATIONAL AIRPORT
   Control
   Method

 Increase
 Idle Speed

M i n i ma I
Engine Taxi
Control led
Gate
Departure
Passenger
Transport
Ai rcraft
Towi ng


Ground-Based
APU

Fuel Drainage
Equi pment
    Implementation
       Requires

1.   Pi lot Procedure
    Change

1.   Pilot Procedure
    Change
2.   Fire-Protection at
    Runway End

1.   Automated  Traffic
    Control

2.   Interim Parking
    Area

I.   Mobile Lounges

2.   Parking Area  Near
    Runways

1.   Tow Vehicles

2.   Revised  Schedules

1.   Air and  Electrical
    Supply Un i ts

1.   Equipment  and
    Personnel
   Advantages Other
    than Emissions
1.   Use Less Fuel
    for same thrust
I.   Expedites  Airport
    Traffic
1.   Use Less  Fuel
1.   Use Less  Fuel
1.
    Constraints and
     D i sadvantages

    Limited by Braking
    Capaci ty

    Limited by Jet Blast
    when Starting from
    Dead Stop
Complicated System
Requires Continuous
Updating
1.   Requi res Ai rport
    Expansion
1.   Requires Much More
    Taxi  Time
                             I.   Clutters  Parking
                                 Area

                             1.   Adds  a  Task  to
                                 Aircraft  Service
                                 Procedure

-------
                             TABLE *Q


CURRENT RANGES OF AIRCRAFT ENGINE EXHAUST EMISSION CONCENTRATIONS
Pollutant
Spec ies
Total
Hydrocar-
bons , ppmC
CO
ppm
NO
ppm
NOx
ppm
(as N02)
Dry Part.
mg/m3
Total Part.
mg/m3
a?
Total
Alde-
hydes
ppm
Turb i ne
Idle
75-
1025
100-
1600
1-
10
5-
19
0-
200
500- .
700
0.9-
2.5%
0.9-
60
Approach
2-
280
30-
\t*o
10-
1*0
10-
60
5-
150
300-
550
].k-
3-2%
0-
20
Cru i se
0-
150
0-
85
10-
110
15-
165
6-
60
200-
550
1.5-
3-2%
0-
20
Take-Off
0-
55
0-
70
7-
125
25-
300
2-
150
200-
i*50
2.0-
i». 1%
0-
30
Piston
Taxi .
3,000-
30,000
3%-
12%

70-
850


6-
12%

Idle
2,000-
30,000
. 5%-
11%

80-
1300


6-
11%
27
Ascent
• 900-
10,000
6%-
12%

90-
600


t*-
!*»%
16
Cru i se
Rich
900-
2800
.5%-
11%

80-
700


7-
13%
33
Cruise
Lean
200-
1800
o.^»%-
5%

600-
4800


11-
15%
18
Descent
900-
35,000
l%-
11%

• 75-
750
-

5-
12%
51
                                                                                         vn
                                                                                         o

-------
                           TABLE  Mt
                                                                151
INSTRUMENTATION  ACCURACY-REQUIREMENTS  FOR  EXHAUST  GAS  ANALYSIS
Pol lutant
Species




Total Hydrocarbons
ppmC





CO
ppm



NO

ppm


NOx (as NO )
ppm


DRK Particulates
mg/m3

Total Particulates
mq/m3
CO
2
(%)

Total Aldehydes
(as HCHO)
Recommended
Ranae

0-10

0-100
0-1000
0-10,000

0-5%
0-10
0-100
0-500
0-2500
0-20,000
0-15%
0-10
0-50
0-250
0-1000
0-5000
0-10
0-50
0-250
0-1000
0-5000
0-10
0-50
0-100
0-250
0-100
0-1000
0-2%
0-5%
0-15%
0-20%
0-10
0-50
0-100
Recommended
Accuracy
+5% full scale with
propane calibration gas
+2% ful 1 scale with
propane calibration gas
+ 1% full scale with
propane calibration gas
+1% full scale with
propane calibration gas
+1% full scale with
propane calibration gas
+5% full scale
+2% full scale
+1% full scale
+1% full scale
+1% full scale
+1% full scale
±5% full scale
±2.5% ful 1 scale
+2% full scale
+2% full scale
+1% full scale
±5% full scale
±2.5% full scale
+2% full scale
+2% full scale
+1% full scale
- +5% full scale
+5% full scale
+5% full scale
±5% full scale
+5% full scale
+5% full scale
+1% full scale
+1% full scale
•*•!% full scale
+1% full scale
+5% full scale
+2% full scale
+2% full scale

-------
                                                                      152
                                TABLE kS
        EXHAUST  GAS  ANALYSIS METHODS IN USE AT 17 ORGANIZATIONS

        Analysis Method                                  Number Using Method
                          Carbon Dioxide
Flame lonization (after conversion  to methane)                    (1)
Gas Chromatography    '                                            (2)
NDIR

                          Carbon Monoxide
Flame lonization (after conversion  to methane)                    (1)
Gas Chromatography                                                (2)
NDIR                                                             (17)

                            Hydrocarbons
Flame lonization with Heated  (*v 350-^00 deg  F)
Sample  Line                                                       (8)
Flame lonization, Unheated  (  <.300  deg  F line)                    (5)
Flame lonization, Line Temperature  not  Reported                   (5)
High Temperature Oxidation  to CO,  ( <£ 300  deg F
line)                            L                                 (1)
NDIR                                                              (1)

                            Nitric  Oxide
NDIR                                                             (12)
Saltzmann Method                                                  (2)
PDS                                                               (2)
Chemiluminescent Method                                           (1)
Electrochemical  Cell                                              (2)
Mass Spectrometer                                                 (1)
Faristor                                                          (1)

                          Nitrogen  Dioxide
NDUV                                                              (*+)
NDIR (by conversion  to NO)                                        0)

-------
                                                                      153
                          TABLE kS  (CONTINUED)
        EXHAUST GAS ANALYSIS METHODS  IN  USE AT  17 ORGANIZATIONS

       Analysis Method                                   Number Using Method^
                          Nitrogen  Oxides
Electrochemical Cell                                              (2)
Chemiluminescent Method                                           (2)
NDUV  (assuming exhaust  is NO and  NO.;  NO previously determined)  (2)
PDS                                                               (2)
Faristor                                                          (1)

                           Particulates
Mass Determination                                                (k)
Mass Determination and Sizing by  Electron                         (2)
Microscope                                                        (2)
Mass Determination and Wet Chemical Analysis                      (2)

                               Smoke
Per SAE, ARP 1179                                                (10)
Other                                                             (3)

                          Sulfur  Dioxide
Calculated                                                        (6)
Faristor                                                          (2)

                             Aldehydes
MBTH                                                              (6)

-------
                                      15**
FIGURES

-------

-------
90
    80
     70
     60
 0)
 3
 I
.d
-    50
O
O
o
-Q
X
V
-o
c
c
o
I/I
'i
     30
     20
     10
           480©
                       
-------
     18
     16
     12
 i
ja
o
o
o
X
0>
c
o
I/I
I/I
     10
       O Data from Reference 6.

         • Data from Reference  118,
          Tables  IV-300  through
          IV-312.
                                             28 (t
              Tl    T2   T3            Tl   T2   T3
                 Idle                  Approach
                        Engine Class and Power Level
                                                                       Q)
                                                               i
                                                                    1

                                                              Tl   T2   T3
                                                               Take-Off
    FIGURE 3 - TURBINE ENGINE EMISSION  DATA.  NITROGEN  OXIDES  (AS NO?)
                                                                                 157

-------

-------
   Assumpt I ons

        Turbi ne Engi nes

        1.   TBO = Time  Between Overhauls
                = 5000  hrs  = 2}2 years

        2.   Engine Life  = 10 years
                                  159

            Pi ston  Enqi nes

            1 .   TBO = 1500  hrs  =  5  years

            2.   Engine Life = 10  years
Cost
 Test!ng
 Tooli ng
 Cost
Servi c
Cost
4
/
ne

nt,
i
e ^ 	
\
Initial
Add i t iona
Instal lat
Cost
%
1
ion
1


\ '
1

»>

Y////////////;

TBO
— Ini

•>
»
t

TBO
ial Con

1
•»
<•.
V(
le

TBO
|
^
*•

TBO


;rsion Time

I

—



Co
--~ Ad
L Co
^ Ad
In
Cc
f
t
T
                                                                      Cont i nuous
                                                                      Add i tional
                                                                      Cost  per  Year
                                                                      Add!ti onal
                                                                      Installation
                                                                      Major Overhaul
                                                                      Ti mes
                 Development,
                 Testing &
                 Tooli ng
                 Time
Time (years)
                   FIGURE $ - EMISSION CONTROL COST/TIME MODEL FOR
                 TYPICAL AIRCRAFT ENGINE FAMILY CURRENTLY IN-SERVICE

-------
                                                                                  160
Class
Class
Class
     9
   322
FAMILIES
ENGINES
1
/
TF39
[1 1
t?
tl
tk
! Development il Implementation
S/Fam
X 10"° Years
o.q
1.8
1.0
1.8
t<; jl 0.6
t6

2.2

S/Eng
x lO"^ Years
2-5-5 il 58.3
5-7-5 1! 100.0
3-5-5
5-7-5
2.5-4
4-6.5
' 7.4
17.2
25-6
9-9
II
10
10
10
10
10
10

    20 FAMILIES
35,874 ENGINES

JT8D i
t] !
t?
t* \
Deve lopment
S/Fam
x. 10~6 Years
0.9
1.8
1.0
t'k li I -8
tj; |! 0.6
tfi i
1
2.2

2.5-5
5-7-5
3-5-5
5-7-5
2.5-4
4-6.5

Implementat ion
§/tng
x. 10--* Years
35.5
60.9
1 4.5
10.5
! 15.6
6.0

10
10
10
10
10
10

    42 FAMILIES
48,773 ENGINES

t]
t?
[3
tl,
:; Class
lj
IS x 10"6
;i 26.8 i
lj 48.4 !
'! 11.3
'I 21.7 i
T3
Years
5-7.5
7.S-10
5.5-8
7.5-10
t5 li 13.9 ' 5-6.5
t.
li 23.0 i
6.5-9
1! i
i! Class T2
1
i
5xlO-6 Ye
a r s "•'•'
t, li 1293 ! 5-7.5
t0 IJ2226 1 7-
13 '
tu !
181 : 5-
412 7.
5-10
5-8
5-10
tq !! 572 5-6.5
tg |
!
258 6.
i
5-9
• "!
                                                                    *To complete initial
                                                                     convers ion

/ jj Development
151 ji $/Fam
llx 10"6 Years
t] il 0.9
t2 1! 1.8
17 li 1.0
t^ II 1.8
C5 i! 0.6
tg, 11 2.2
2-5-5
5-7-5
3-5-5
5-7.5
2.5-4
1 mplementat i on
U/Eng
Ix 10"3 Years
12.4
21.3
10
10
1.6 | 10
1 3-7 i 10
5-5
4-6. b il 9 1
•^ 11 ^ • '
li ! li
10
IU


J
FIGURE 6 - SUMMARY OF TOTAL. TURBI NE ENGINE
.XV
POPULAT

Class Tl
!$ x 10"6 Years
t, il 643 1 5-7-5
t2 II 1116! 7-5-10
t, j| 12C ! 5-5-8
t^ !| 257 i 7-5-10
tj.
t^

| 295 i 5-6.5
1 196 ! 6-5-9
I 1
ION
                               COST/TIME ANALYSIS PROCEDURE

-------
                                                                                    161
Class PI
     35 FAMILIES
136,166 ENGINES

Opposed
Piston
Dl
D2
P-,

Pr
! Development
:1$/Fam
Jix 10"3 Years
iP272
!! 728
li 641
il 728
i! 251
p£ II 105
P7
!j 127
1.5-3
3-6
i Implementation
S/En.g
|c 10~3 Years
1.23
10
3.15 1 10
2.5-5 li 3.98
10
3-6 II 3.15 ! 10
1.5-3 ! 0.60
1-2
1.5-2.5
0.70
2.00
10
10
10


D,
P2
P3
Pz,
PC
P6
P. . 1
i Clas
$ x 10"6
176.5 •
^53- 6 i
56k. k l
453-6;
90.8;
1 98.7!
1.276.5 1
s PI
Years
6.5-8
8-11
7.5-10
8-11
6.5-8
6-7
6.5-7.5
                         FIGURE 6A - SUMMARY OF TOTAL PISTON ENGINE
                          POPULATION COST/TIME ANALYSIS PROCEDURE

-------
                                                                                   162
 Class T3
Class T2
Class Tl
                             7 FAMILIES
                            6k ENGINES
r
/
I im
ti
to
13
tL
tr
t£

Development
S/Fam/.
Ix 10"b Years
Implementation
$/Eng,
x 10 3 Years
O.q 1 2.5-5 li 58.3
1.8 5-7.5
i.o
1.8
0.6
2.2

3-5.5
5-7-5
2.5-4.
4-6.5

100.0
1 7.4
17.2
25.6
q.q

10
10
10
10
10
10

                                  A
                              10 FAMILIES
                           6,576 ENGINES

/
^JT8D
t,
t?
I Development
;$/Fam
Ix 10"b Years
0.9
1.8
t, || 1.0
tif il 1.8
tc
ti

0.6
2.2

2.5-5
5-7-5
3-5-5
Implementat ion
$/Eng
x lO'-J Years
35-5
60.9
**-5
5-7-5 !! 10.5
2.5-Jf
i|-6.5

15.6
6.0

10
10
10
: 10
10
10

                               FAMILIES
                               ENGINES

/ li Development
T53 .$/Ta?T
|p( 10-b Years
ti II 0.9
t, !' 1.8
t-.
ti;
tr
t£

1.0
1.8
0.6
2.2

2.5-5
5-7.5
3-5-5
5-7-5
2.5-4
4-6.5

Implementat i on
5/Eng
x lO--* Years
12.4
21.3
1.6
3.7
5o5
2.1

10
10
10
10
10
10


ti
to
i Class T3
$ x 10" Years
10
! 1Q
5-7-5
7.5-10
t; !! 7 ! q.q-8
"
t^
t,.
t^
14 I 7.5-10
6
16
6 1
5-6.5
6.5-9






                                                                     ^To complete initial
                                                                      conversion
                     FIGURE 7 - SUMMARY OF AIR. CARRIER TURBINE ENGINE
                          POPULATION COST/TIME ANALYSIS PROCEDURE

| Class
i $ x i cr6
t! II 243 !
to
T2
Years-
5-7.5
1 418 i 7-5-10
t; ii 40 •
tu
87 !
tq li 109 !
t6 H 62 ;
6 li i
5-5-8
7-5-10
5-6.5
6-5-9 :


t,
ro
t^J
t?
U
fr

Class Tl
$ x 10"6 Years
19
35
5-7. q
7.5-10
8 i 5.5-8
15
10
16

7-5-10
5-6.5
6.5-9


-------
                             0 FAMILIES
                             0 ENGINES
1
/
IE12
ti
to
t7
tii
t«;
t*

Development
$/Fam
x 10~b Ypars
0.9
1.8
1.0
1.8
0.6
2.2

2.5-i)
5-7-5
3-5.5
Implementation
$/Eng
x in-3 Ypsrs
58.3
100.0
7.4
5-7.5 II 17.2
2.5-4
4-6.5

25.6
q.q

to
10
10
10
10
10

Class T2
Class'Tl
    2 FAMILIES
      ENGINES

JT8D
Development
$/Fam
x ID'6 Years
t, :: 0.9
t2
ti
''i
tc
t6

1.8
1.0
1.8
0.6
2.2

2.5-5
5-7.5
3-5.5
5-7-5
2.5-4
4-6.5

Implementat ion
$/Eng
x 10"3 Years
35.5
60.9
4.5
10.5
15.6
6.0

10
10
10
10
10
10

   16 FAMILIES
6,137 ENGINES

(^
t]
t2
t3
t'",
tq
tfi

Development
$/Fam,
x 10'6 Years
0.9
1.8
1.0
1.8
0.6
2.2

2.5-5
5-7-5
3-5.5
5-7-5
2.5-**
4-b.5

Implementat ion
$/Eng
x 10-3 Years
12.4
21.3
1.6
3.7
5.5
2.1

10
10
10
10
10
10

                                                                                  163

t]
1 Class T3
$ x 10"6 Years
0
U il 0
t; ii o
U I 0
tp
! 0
tg ! o

1
5-7-5
7.5-10
5.5-8
7-5-10
5-6.5
6.5-9

                                                                    *To complete initial
                                                                     conversion
                 FIGURE 8 - SUMMARY OF GENERAL AVIATION TURBINE ENGINE
                        POPULATION COST/TIME ANALYSIS PROCEDURE

Class T2 '
$ x 10'6 Years^
t , il 18
to
t^
tL\
t5'
tr

31
k
8
8
7
5-7. «;
7-5-10
5-5-8
7-5-10
5-6.5
6.5-9
1

Class TI
$ x 10"6 Years
ti !l 91
to
t^
tL
^
tft

159
26
52
^
<48

5-7-5 !
7-5-10
5-5-8
7-5-10
5-6-5
b.i-9


-------
Class T3
 7 FAMILIES
64 ENGINES
1
/
TF39
Development
$/Fam
x IO"6 Years
t] li 0.9
t?
1.8
ti j! 1.0
t,-;
tc
u

]«8
0.6
2.2

Impl ementat ion
$/Eng
x 10'3 Years
2.5-5 il 58« 3
5-7.5 11100.0
3-5.5
5-7.5
2.5-4
4-6.5

7.4
17.2
25.6
9.9
I
10
10
10
10
10
10

                             12
                          7,024
   FAMILIES
   ENGINES

/
JT8D

t.
t^
Development
$/Fam,
x 10 Years
0.9
1.8
t; it i.o
t,
tc
t6

1.8
0.6
2.2

2.5-5
Implementat ion
$/Eng
x 10"-* Years
35.5
5-7.5 ft 60.9
3-5.5
5-7.5
2.5-4
4-6.5
4.5
10.5
15.6
6.0
II
10
10
10
10
10
10

                             22 FAMILIES
                          7,251 ENGINES
                                                                                  164

t,
tn
tt
til
tc
t£

Class T?
$. x 10~6 Years
10.0
19.0
5-7.5
7.5-10
7.4 1 5.5-8
13.7 1 7.5-10
5.9
16.0

5-6.5
6.5-9


t,
to
'3
t7,
tc
t£

Class T2
$ x 10"6 Years*
260 ,
450
44
95
117
69

5-7.5
7.5-10
5.5-8
7.5-10
5-6.5
. 6.5-9

                                                                    *To comp1e te initial
                                                                     conversion

/
lii
t]
t?
13
t
tc
^

Development
$/Fam
x 10'6 Years
0.9
1.8
1.0
1.8
O.b
2.2

2.5-5
ij-/«.b
3-5.5
5-7.5
2.5-4
4-6.5

Implementation
$/Eng
x 10-3 Years
12.4
21.3
1.6
3-7
5.5
2.1

10
10
10
10
10
10


t]
t?
t*
t/,
tc
t^

Class Tl
$ x 10'6 Years
1 10
194
34
66
53
64

5-7-5
/.5-IO
5-5-8
7.5-10
5-6.5
6.5-9

                  FIGURE 9 - SUMMARY OF CIVIL .AVIATION TURBINE ENGINE
                        POPULATION COST/TIME  ANALYSIS PROCEDURE

-------
                                                                                   165
Class
     3*»  FAMILIES
134,760  ENGINES

/ Ij Development
Opposed !i$/Fam_
Piston ilx 10'3 Years
pi !: 272
. P2 ij 728
P3 i| Ml
p4 ji /ZB
P5 il 251
p6 1! 105
P? I 127
! Implementat ion
fc/Eng,
be ID"3 Years
1.5-3 1! 1.23
3-6 ! 3-15
2.5-5
3-b
1.5-3
1-2
3-98
3. 15
0.60
0.70
1.5-2.511 2.00
10
10
10
10
10
10
10

1 Class
$ x 10"6
pi ii 17^.5i
p2 j! 448. k\
P3 i| 55b.b|
pk
P5
p6
M»8.M
89.7!
97.6!
P7 II 273.31
PI
Years i
6.5-8
8-11
7.5-10
8-11
6.5-8
6-7
6.5-7.5
                NOTE:  Air carrier piston engine population assumed negligible.
                       Therefore, air carrier population ° civil aviation population.
                    FIGURE 9A -  SUMMARY OF CIVIL AVIATION PISTON ENGINE
                          POPULATION COST/TIME ANALYSIS PROCEDURE

-------
Class
Class T2
Class TI
     2 FAMILIES
   258 ENGINES
'
TF39
Development
$/Fam
x 10"b Years
ti II 0.9
to
t-.
J
tl
t7
J
L
1.8
1.0
1.8
0.6
2.2

2.q-t;
5-7.5
•}_c;_q
5-7.5
2.5-4
4-6.5

Implementat ion
$/Eng
x 10'3 Years
58.3
100.0
7.4
17.2
25.6
9.9

in
in
in
in
in
10

                                  A
     8 FAMILIES
28,850 ENGINES

JT8D
tl
t,
t.
t/i
C5


Development
Implementat ion
$/Fam |j$/Eng
x 10-6 Years Ijx 10"-> Y^^rc
0.9
1.8
loO
i.a
0.6
2.2

2.5-5 II 35.5
5-7.5
3-5.5
5-7.5'
2.5-4
4-6.5

60.9
4.5
10.5
15.6
6.0

10
10
10
10
10
10

    20 FAMILIES
41,522 ENGINES

111
t]
t?
t-}
^
tq
t£

Development
x ID"6 Years
0.9
1.8
1.0
1.8
0.6
2.2

2.5-5
5-7.5
3-5.5
5-7.5
2.5-4
4-6.5
Implementat ion
$/Eng
x 10-3 Years
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                                                                                    167
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                                                                     168
FIGURE 11 - IMPLEMENTATION COST PER ENGINE VERSUS NORMALIZED
             COST PARAMETERS FOR TURBINE ENGINE

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8000
per
hour
6000
4000
2000
•Fuel  Flow

 (Turboprop)
                                                                           169
             800
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 600
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                                                        Class 5


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                                                                 * Class 6
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            Idle
                      50   '      Per Cent
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                  FIGURE  12.-.FUEL FLOW PLOTTED AGAINST POWER
                          FOR EACH AIRCRAFT CLASS ..

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                                                                     170
   CO
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 20  -
               Class 3
                                  50
Per Cent
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    FIGURE 13 - CO EMISSION FACTORS PLOTTED AGAINST  POWER
                   FOR EACH AIRCRAFT CLASS

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Hydrocarbons
  Emissions
   30 h
   x
  1000
 grams
  per
 hour
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   10
                                                                       171
                    Class  3
                                                                    Power
                                   50
Per Cent
100
           FIGURE \U -  HYDROCARBON EMISSION FACTORS PLOTTED
                 AGAINST  POWER FOR EACH AIRCRAFT CLASS

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                                                                      172

                               APPENDIX
                            INSTRUMENTATION

 Introduction
          The formation of the Committee on Aircraft Exhaust Emissions
Measurement (E-31) by the Society of Automotive Engineers in 1968
represents a significant step towards the development of acceptable
standards for characterization of aircraft engine exhausts.   This com-
mittee has issued an Aerospace Recommended Practice  (ARP-1179) on
"Aircraft Gas Turbine Exhaust Smoke Measurement" (Ref 55) that has been
widely accepted and adopted as a standard procedure by the aerospace
community.  Furthermore, the committee is completing work on a "Procedure
for the Continuous Sampling and Measurement of Gaseous Emissions from
Aircraft Turbine Engines" (Ref 36) that specifies instrumentation,
sampling, and test procedures that shall be used for measurement of
carbon monoxide, carbon dioxide, nitric oxide, and total hydrocarbons
 in turbine exhausts.  Before being discharged of its responsibilities, the
committee will also examine procedures for odor characterization and
measurement of particulates also in turbine engine exhausts.  They will
also reexamine the areas of emissions sampling procedures in the light of
discoveries made subsequent to their recommendations on smoke measurement.
          The forthcoming recommendations of the E-31 Committee on the
characterization of aircraft gaseous emissions reflect a state-of-the-
art analysis of existing measurement hardware.  The committee's report
does not, however, discuss alternative measurement techniques; it
instead specifies standard measurement techniques and procedures that
are to be followed in the aerospace community to insure the validity
of data comparisons from one test program to another.
          Consequently, to complement rather than duplicate the E-31
Committee's work, this discussion is directed towards various alternative
 instruments both available now, and under development, that cpuld be
used in an aircraft emissions measurement test program.  This
discussion will not include comparison of the cost and performance of

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                                                                    173
the various brands of a specific type of instrument; the reader is
referred to a recent study by Arthur D. Little, Inc. for such a com-
parison (Ref 60).  Reference 61 also contains information on cost and
detection principles for a number of commercially available continuous
moni tors.
          In this Appendix, measurement techniques are discussed for the
following ,pollutant classes:
          Carbon Monoxide  (CO)
          Carbon Dioxide (COj
          Total Hydrocarbons
          Nitric Oxide (NO)
          Total Nitrogen Oxides (NOx)
          Sulfur Dioxide (S02)
          Aldehydes
          Particulates
          Smoke
          Odor
The discussions  include, where data are available, reference to performance
characteristics, sensitivity, response time, costs, ease of use, auxiliary
equipment requirements, and portability for each specific type of instru-
ment.  Problem areas indigenous to each instrument type are enumerated;
instrumentation under development is identified; and, wherever applicable,
the recommendations of the SAE E-31 Committee are cited.

Measurement Techniques

                            Carbon Monoxide
          As discussed by  Broderick et al  (Ref 59), carbon monoxide
emissions in aircraft engine exhausts are  now measured by nondispersive
infrared analyzers, by electrochemical analyzers, by mercury vapor
analyzers, and by gas chromatographs.  At  the present time, the most
widely accepted and used of these instruments  is the NDIR analyzer.
The  instrument provides on-line analysis of emissions, has been suc-
cessfully used  in the field as a portable  unit  (Ref 3), can be easily

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operated by unskilled personnel, and carries the recommendation of the
SAE E-31 Committee as an industry standard (Ref 36).

                                 NDIR
          In an infrared analyzer, radiant energy passes through a cell
containing a reference gas and a cell containing the sample gas.  In
the sample cell, the radiation is absorbed by the components of interest
in regions where that specie has absorption bands.   The percentage
absorption relates to the concentration of that specie.  Interference
from other components of the sample gas that absorb in neighboring
bands is eliminated by optical filters or filter cells.  In the reference
cell, attenuation of the reference beam is negligible.
          After passage through the cells, the radiant energy passes
into a detector unit-- a closed container comprised of two compartments
separated by a metal diaphragm.  Both compartments are filled with the
species of interest  in the gaseous state.   The incoming energy from the
sample cell heats the gas in one compartment while the energy from the
reference cell heats the gas  in the other.  The difference in incoming
energy causes a pressure differential in the detector that leads to a
deflection of the cell diaphragm.
          Between the dual infrared energy sources is an optical chopper
that chops the energy beams at a prescribed frequency.  This chopping
causes the diaphragm to pulse cyclically.   Since the diaphragm  is part
of an amplitude modulation circuit, the pulsing causes a concentration
related change  in its capacitance that is ultimately relayed to a
recorder and/or controller as an electrical signal.  Cost of an NDIR
analyzer is in the vicinity of $3500 with the cost dependent on the
user's choice of concentration level, dynamic range, and packaging
arrangement.
          Infrared analyzers  suffer from two significant deficiencies.
interference from other molecular species, and lack of sensitivity,
stability, and specificity at  low concentration levels.  For CO mea-
surement, the first of these  deficiencies is primarily caused by the

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                                                                     175
presence of C0_ and HO in the sample stream.  This interference can,
fortunately, be largely eliminated by desiccants, absorbers, optical
filtersiand filter cells.   However, until recently, the second deficiency
could only be circumvented by the use of alternative Instrumentation
(e.g., a gas chromatograph) for engines operating at high power levels
(low CO emission rates).
          A state-of-the-art advancement in NDIR-instrumentation has
come about with the development of a-fluorescent source carbon monoxide
NDIR analyzer (Refs 62 and 63) •  This analyzer eliminates all unwanted
infrared radiation from the sample source and thus from the analysis
procedure (i.e., there  is no interference from other constituents of
the sample stream).  The detector  is typically solid state or pyroelectric
and hence, free from the .s.tabi 1 i ty problems associated with the typical
gas-filled detector (Ref>62) •  The instrument uses two isotopes of CO
as sources of fluorescent radiation and operates on a single optical
path thus eliminating the requirement for a separate standard cell.
Although still  in the prototype stage, the instrument has been accepted
by NASA for use on board the first orbiting sky lab (Ref-.£4).  Prototype
costs are estimated at $10,000-$15,000.  After commercialization, the
instrument is expected to reach a competitive cost position with existing
NDIR instruments.

                            Electrochemical
          Electrochemical  analyzers operate through a wet chemical process
where the transducer converts specie concentration to a current signal
by an electroxidation or electroreduction reaction.  For carbon
monoxide determination this reaction is SCO + 10  	i-p-
5CO  + I. (Ref 65).  The instrument is accurate at low concentrations
provided the sample stream.is properly dried to eliminate possible
interference from water.  The units cost approximately $2000 to $2500
and are thought to.require operation by skilled personnel (Ref 59).

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                                                                     176

                        Mercury Vapor Detectors
          The basis of operation of these detectors is the reaction
between carbon monoxide and mercuric oxide:  CO + HgO 	-—*-
CCL + Hg.  The elemental mercury liberated in this reaction is measured
and related to the carbon monoxide content of the sample stream.  Since
the analysis can be affected by hydrocarbon interference, sample lines
must be cooled to condense out these unwanted species.   The primary
advantage of mercury vapor detectors is their reputed accuracy at low
concentration levels (Ref 59)-
                          Gas Chromatographs
          All gas chromatograph instruments are comprised of six
basic elements:  a carrier gas supply system, a sample injection system,
a separation column, a column oven, a detector, and a signal output
system.  The heart of the system is the separation column which can be
either a flame ionization detector, a thermal conductivity detector,
or an electron capture detector.
          In a flame ionization detector, the change  in  ion concentration
during combustion of organic compounds relates to the carbon content
of the sample stream.  In a thermal conductivity detector, the difference
in the thermal conductivity of the species in the sample stream is
responsible for a different ability of each component to conduct heat
away from a set of filaments, causing a change in filament temperature.
The degree of this change is recorded by the signal detection system and
is proportional to each species concentration.  The basis for operation
of an electron capture detector is the difference in  the ability of
different compounds to-capture "free" electrons.   Using nitrogen as a
carrier gas, the detector ionizes the nitrogen molecules to liberate
free electrons.   The change in the electron concentration, recorded
as a change in current output, is a measure of the amount and electron
affinity of the specie(s) present.
          Gas Chromatographs are primarily thought of as laboratory
tools for use with grab samples from aircraft engine exhausts.   However,
by installation of an automatic sampling valve, a chromatograph can be

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                                                                     177
easily adapted for continuous monitoring in an emissions measurement
program.   Contrary to popular belief, chromatographs are easy to operate;
it is the interpretation of their data that presents a source of diffi-
culty to the unskilled operator.
          Gas chromatographs offer the advantages of wide dynamic range
(0.1  - 1000 ppm) and high measurement accuracy.   Although the basic
laboratory units are expensive (approximately $7000 including recorder),
the units can monitor several molecular species concurrently.  Further,
                                                                  2
one particular gas chromatograph, a small  (occupies less than 1  ft
of bench space), light (35 lb), portable unit, has now been developed
to sell at $1250 plus $1000 for the recorder system.  Such a unit would
be an excellent supplementary tool to an NDIR unit for low level emissions
monitor ing.

                             Supplemental
          A wet chemical technique also exists for the determination
of CO  (Ref 65.).  In this technique, the sample gas  is first cooled and
passed through an absorption train to remove unburned hydrocarbons,
C0_,  and other  interfering species.  The stream  is then heated
electrically,converting the CO to CO .  The CO   is then absorbed  in a
standard barium hydroxide solution and the excess barium hydroxide
titrated with hydrochloric acid.   The technique  is accurate to a  lower
limit of about  1 ppm.  There is no known carbon monoxide monitor which
operates on this principle.
          A second wet chemical technique for quantitative analysis of
carbon monoxide content in a gas stream involves the use of the carbon
monoxide indicator tube.  When highly purified silica gel, impregnated
with ammonium molybdate and a solution of palladium or palladium  oxide,
is digested  in  suIfuric acid it forms a si1icomolybdate which on
exposure to CO  forms molybdenum blue.  The depth of color  in the  detector
tube varies from faint green to deep blue in proportion to the amount
of CO present  in the gas sample.   This method can be on a continuous
basis for sampling CO by aspirating a metered flow of air through the
tube at a constant rate and observing the color  change with  respect to

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                                                                      178
 time.   The  procedure  is  not  now known  to  be  in  use  in  monitoring  air-
 craft  exhaust  gases;  it  has,  however,  been used for  sampling  aircraft
 turbine exhausts  with  some degree  of success  in the  past  (Ref 66).

                             Carbon Dioxide
          Carbon  dioxide is  a major constituent of aircraft engine  ex-
 hausts.   Present  in percentage level quantities in both  turbine and piston
 engine exhausts,  it  is most  frequently measured by NOIR  analysis  equip-
 ment.   Gas  chromatographic techniques  are also  employed  but generally
 only for laboratory analyses  of engine grab  samples.   Batch Orsat type
 analyses have  been employed  in the past (Ref  50), but  are no  longer in
 use.
          The  SAE E-31 Committee recommends  NDIR instruments  as  the s_tan-
 dard device for determination of C0_  in turbine engine exhausts  (Ref 36).
 A description  of  the  principle of  operation  of  NDIR  analyzers and gas
 chromatographs is presented  in the discussion of carbon  monoxide
 monitoring  equipment.

                          Total Hydrocarbons
          The  concentration  of total hydrocarbons  in aircraft engine
 exhausts is most  frequently  measured with a  flame  ionization  detector.
 Optical  spectrophotometers are also used  (Ref 66); gas chromatographs
 and mass spectrometers are used if determination of  specific  constituent
 concentrations is required.   In all cases,it  is imperative that  the sample
 line to the instrument be maintained at 300  to  350 deg F  to avoid conden-
.sation of the  less volatile  hydrocarbon constituents in  the sampl«>  <=» i-

                                   FID
          The  principle  of operation of flame ionization  detector has
 been previously discussed in  the section  dealing with  carbon  monoxide:
 gas chromatographs.  To  reiterate,  the flame  formed  by combustion of
 pure hydrogen  with air produces a  negligible  source  of ions.   If  a
 sample gas  containing  hydrocarbons is  introduced into  the flame,  a

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                                                                      179
complex ionization process occurs liberating a large number of ions.
By applying a voltage across the flame, a small ionization current  is
established in the detector system.   This current is then directly
proportional to the carbon atom concentration of the flame.
          FIDs have been shown to have poor measurement characteristics
below about 10 ppm in turbine exhausts (Ref ^1), although they are
reputedly able to make measurements  of hydrocarbon concentrations down
to 1  ppm.   On the more positive side, FIDs can be used for on-line
analysis of emissions, have been successfully employed in the field
as portable units (Ref 3), can be easily operated by unskilled personnel,
and carry the recommendation of the SAE E-31 Committee as an industry
standard (Ref 36).  Their cost is approximately $5500.

                      Optical Spectrophotometers
          NDIR spectrometers similar to those used for CO and C02 can
also be used for- determination of total hydrocarbons in exhaust emis-
sions.  George and Burl in (Ref 66),  for example, report collection of
grab samples from aircraft exhausts and their analyses with an IR
spectrophotometer set at the 3**5Q^#.  This technique clearly requires
elaborate calibration procedures and has therefore not seen wide
application in aircraft emissions measurement programs.

                          Gas Chromatography
          The instrument best suited for the constituent analysis of the
total hydrocarbon measurement is the gas chromatograph.  Linear tem-
perature programming  is generally employed to elute all individual
organics with a sensitivity less than I ppb (Ref 67).  The technique
is most frequently applied to grab samples of the exhaust stream.
FID units are not suitable for this  type of measurement as they are
not sensitized for a particular compound but, instead, detect all
classes of unburned hydrocarbons (Ref 68).

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                                                                      180
                          Mass Spectrometers
          Time of flight mass spectrometers operate on a principle of
separation of species according to their mass number.  The separation
is accomplished by ionizing the sample, accelerating the ionic species via a
grid system, and allowing the ions to drift through a region at the
nominal ion energy.  Since heavier ions travel slower than those of
lighter mass, a separation of the different molecular constituents is
ach ieved.
          Mass spectrometers are expensive units (about $15,000), require
the use of highly skilled operators, and are not suited for field use.
Their use in aircraft emissions analysis programs has been all but
nonexi stent.

               Nitric Oxide and Total Oxides of Nitrogen
          Nitric oxide and total oxides of nitrogen are measured by a
variety of overlapping techniques.  These methods include classical
batch wet chemical colorometric procedures, electrochemical analyzers
similar to those used for measurement of carbon monoxide, nondispersive
infrared spectrometers for measurement of NO, nondispersive ultraviolet
spectrometers for measurement of NO , gas chromatographs, faristors,
and chemiluminescence monitors.  The SAE E-31 Committee presently
recommends the use of NDIR units for measurement of NO, NDUV units for
measurement of NO  , and makes no recommendation for total NOx monitoring
equipment (Ref 3&) •  However, at this writing, chemiluminescence monitors
are undergoing extensive field testing by the EPA and may become the
industry standard for continuous measurement of NO and NOx.
          Sampling problems associated with measurement of emissions
are discussed earlier in this report.  However, it is imperative to
keep  in mind that: (1) NOx can be reduced by CO if catalyzed at elevated
temperatures by any of a variety of the metallic surfaces that are
frequently employed in sampling lines;  (2)  NO can be similarly catalyzed
to NO^; and  (3)  N02 can be easj.l.y lost  in the drying of the exhaust
sample prior to analysis . (Ref ^2).

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                                                                      181
                        Wet Chemical Procedures
          Many wet chemical procedures for the determination of nitric
oxide depend on the oxidation of the oxide to nitrogen dioxide.  The
sample is bubbled through an acid potassium permanganate solution where
all of the nitric oxide present is converted to an equivalent amount of
NO. (Ref 69).  The NO concentration is then determined by an optical
measurement of the color intensity produced by the reaction of the NO
with appropriate reagents.   Since NO and N0_ are the primary nitrogen
oxide constituents of aircraft engine exhausts, it is appropriate to
test a given sample twice  (or split the sample stream for individual
analyses)-- once for determination of the NO  content of the NOx and
once for determination of  the total NO and NO. in the sample.  The NO
concentration is determined by difference.
          The Jacobs and Hochheiser technique for determination of NO
(Ref 70) is frequently employed in the presence of high concentrations
of sulfur dioxide.  Air is aspirated through a fritted bubbler in  a
sampling train containing  a nitrogen dioxide absorbing solution.   The
absorbed nitrogen dioxide  is determined colorimetrically as the azo
dye.  Nitrogen dioxide concentration of the order of parts per hundred
million can be determined  by this technique.  Another method used for
NO. determination is based on the absorption of nitrogen oxides by a
solution of mixed reagent  consisting of sulfanilic acid, o£-naphthylamine,
and acetic acid in a glass bubbler (Ref 70-  The color produced is
compared to standards or observed spectrophotometrically at a wavelength
of 550 nanometers (nm).   ASTM designation E1607, issued in 1958, is a
modification of the above  principle, the major changes being the substi-
tution of N-(l, naphthy1)-ethylene diamine dihydrochloride for
 «•£• -naphthylene as the coupling agent and the use of a fritted bubbler
instead of an ordinary glass bubbler.   Again the resultant color can be
read with a spectrophotometer set at 550 nm.
           In the phenol disulphonic (PDS) acid procedure, the gas
sample  is fed  into an absorbent solution of hydrogen peroxide  in dilute
sulfuric acid.  The oxides of nitrogen  (NO and NO ) are converted to

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                                                                      182
nitric acid by the absorbent and the resulting nitrate ion reacted with
PDS to produce a complex whose yellow color is read colorimetrically
(Refs 72 and 73)-   The PDS procedure is recommended for gaseous mixtures
containing NOx from 5 to several thousand ppm.  It is specific only for
the total NOx in the exhaust stream.  No definite trend attributable
to contaminants ;n the exhaust stream has been noted for the PDS
procedure (Ref 7*0.
          The most commonly used wet chemical analysis method for
nitrogen dioxide and nitric oxide is the Saltzman method (Refs 69 and
75).  This method is intended for manual determination of nitrogen
dioxide in the atmosphere in the range of a few parts per billion to
about five parts per million.  The sample is obtained by drawing air
through fritted bubblers and nitrogen dioxide is absorbed in Griess-
Saltzman reagent (Ref 65).  A stable pink color is produced and may be
read visually or spectrophotometrically at 550 nm.  This method is also
applicable to the determination of nitric oxide after it is converted to
an equivalent amount of nitrogen dioxide by passage through a potassium permanganate
bubbler.  Ozone and sulfur dioxide are known to interfere with Saltzman
measurements (Refs 69 and 7^); however, their concentrations in aircraft
exhausts are usually not high enough to cause significant difficulty
with the technique.
          Another technique that has not seen much application to aircraft
engine,.exhaust analysis is the Griess-Ilosvay (Gl) colormetric method
(Ref 65).  A high-pressure mercury vapor lamp is used in the presence
of a butadiene solution to oxidize NO photochemically to NO .  The N0_
is absorbed in the Gl reagent and the  intensity of color measured.  For
simultaneous determination of NO and N0?, the sample stream is divided
into two portions with the NO in one converted to N0» by passage through
an acidified solution of potassium permanganate.   Both streams are then analyzed
for N07 content by the previously discussed procedure that employs an
absorbing solution of sulfanilic acid, N-(l-naphthy1)-ethylenediamine
dihydrochloride and acetic acid.

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                                                                     183
          All of these methods are batch type analyses which are slow,
require skilled personnel for performance, and do not yield continuous
data.   Some investigations have incorporated these techniques into
continuous analyzers by using a spectrophotometer and appropriate
valving.   For example, Ganz and Kuznetsuo (Ref 76) have developed an
automatic recording gas analyzer based on the measurement of the varia-
tion of the pH of a solution with the concentration of the oxides of
nitrogen in the gas stream passing through it.  Its operating principle
is that the interaction of nitrous gases with the absorbent  (5 per cent
hydrogen peroxide) yields a weak nitric acid solution and the change  in
concentration of the acid is dependent on the specific gravity and con-
centration of the gas passing through the solution.

                      Electro-Chemical Analyzers
          Electro-chemical analyzers similar to those used for carbon
monoxide can also be used for determination of NO  and NOx concentration
in exhaust emissions.  The units range  in cost from approximately $2000 to
$3000 with cost dependent on range anduthe SO  concentration  in the
stream.  The principle of operation and the relative advantages and
disadvantages of this instrument .are discussed in the section on carbon
monoxide measurement.

                                 NDIR
          NDIR spectrometers similar to those used for CO and C0?
can also be used for determination of nitric oxide in exhaust emissions.
This technique is,  in fact, the proqe.dure recommended by the SAE E-31
Committee for NO determination  (Ref 36).  The procedure is accurate and
reliable j_f_ care  is taken to eliminate  interference from other species
present in the exhaust, especially water vapor.  A combination of optical
filters and drying  agents are  the most  widely used methods of discrimi-
nation.  This interference problem is most acute at low concentrations
of nitric oxide.

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                                 NDUV
          NDUV units have been recommended by the SAE E-31 Committee for
NCL determination in turbine engine exhausts since it is now accepted
that NO and NO. are the prime nitrogen oxide constituents in aircraft
exhausts.  The principle of operation of NDUV units is as NDIR units;
only a different portion of the spectrum and a different optical cell
path length are employed.

                          Gas Chromatographs
          Gas chromatographs are well suited for the analysis of the
oxides of nitrogen especially at low concentration levels where they
would make excellent supplemental tools for NOIR and NDUV units.
Their relative advantages and disadvantages are discussed in the
section on carbon monoxide measurement.

                               Faristors
          Faristor is the trade name of a "plug-in sensor" marked
by Environmetrics Inc.   These units are low cost ($1750 to $2300)
electronic multigas analyzers that are "liquid-state nonohmic variable
resistors in which a pollutant-selective activating surface ruptures
the gas molecular bonds, releasing energy as a voltage signal proportional
to the pollutant concentration" (Ref 77)«  Faristors are sensitive to
NO, N0_, NOx, and S0_ with various modular units available for differ-
ent ranges of each of the species of interest.  Avco Lycoming (Ref 39)
is evaluating the applicability of these instruments for aircraft
exhaust measurements.  Their sensitivity in this application is as
yet unknown.

                      Chemiluminescence Monitors
          As evidenced above, most of the instruments and procedures
for determing oxides of nitrogen depend on coulometric or colorimetric
techniques.  The chemiluminescent procedure depends instead, upon the
formation of electronically excited nitrogen dioxide by the rapid reaction

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                                                                     185
of nitric oxide with ozone and the subsequent emission of optically
detectable light (Refs 78, 79, and 80).  Total oxides of nitrogen are
determined by thermal conversion of the nitrogen dioxide in the sample
to nitric oxide and remeasurement of the total NO.
          This procedure has a reported sensitivity from 1  ppb to
1000 ppm and offers the added advantages of continuous monitoring
without interference from other (pollutant) species typically present
in aircraft exhausts.  Chemiluminescent units are now available in
both modular and self-contained configurations and require only a small
vacuum pump as auxiliary equipment.  Instrument operation is possible
by unskilled personnel; cost per unit  is between $5^75 and $10,800,
depending on the range and configuration requirements and on whether
the unit is required to measure NO or NO and NOx.
          Application of this instrument to engine exhaust measurement
has shown it highly satisfactory for measurement of nitric oxide (Refs
81 ,and 82).  Measurement difficulties have, however, been encountered
for measurement of NOx  (Ref ^0) particularly  in turbine exhausts where
NOx £ NO.  Chemiluminescence units are now undergoing extensive testing
in the EPA's aircraft emissions baseline data collection program; the
results of this program should determine its suitability as a standard
for NO and NOx emissions quantification.

                            Sulfur Dioxide
          Sulfur oxides in aircraft engine exhaust is produced by the
combustion of sulfur impurities in the source fuel.  It is generally
accepted that all  of the sulfur present in the fuel is converted to
sulfur dioxide during engine operation; hence, it  is standard procedure
to calculate, rather than measure, the SO- content of the exhaust stream.
This can be done from a knowledge of the fuel's sulfur content, and of
the fuel-to-air ratio and fuel flow rate for the prescribed engine
operating conditions.
          Measurement of SO-  in engine exhaust is most frequently
accomplished by batch wet chemical analysis procedures although some
of these techniques have been adapted  for use in continuous monitoring

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                                                                      186
equipment.  The S0? content of aircraft exhausts can also be monitored
by Faristors, by electrochemical and conductivity analyzers, and by
remote spectrometers.  These techniques are, at most, infrequently
employed and are only mentioned here for completeness.

                             Wet Chemistry
          Katz (Ref  65) reports a large number of wet chemical pro-
cedures for determination of S0?; however  only the  West-Gaeke (Ref
83) and hydrogen peroxide methods (Ref 69) are widely used.
          In the West-Gaeke procedure, the sulfur dioxide  is reacted
with sodium tetrachlormercurate to form an intermediate dichloro-
sulfitomercurate ion..  This ion is reacted with acid-bleached p-
rosaniline and formaldehyde to produce a red-purple color  that may
be read visually or spectrophotometrically.  Nitrogen dioxide is
known to  interfere with this determination if the N(L is present at
concentrations greater than that of the sulfur dioxide.  Fortunately,
the NO. can be eliminated as an obscurant by addition of sulfamic acid
to the absorbent.  The technique is applicable for determination of SO.
in the range 0.005 to 5 ppm and is more sensitive than the hydrogen
peroxide  technique discussed below.
          In the hydrogen peroxide technique, sulfur dioxide is absorbed
in a solution of hydrogen peroxide which oxidizes it to sulfuric acid.
The solution acidity is then determined by titration with  a standard
alkali solution.  This method  is the preferred procedure if SO. is the
principle acid or basic atmospheric pollutant present in the exhaust
gas stream;  it is simpler to conduct than the West-Gaeke procedure and
applicable  in a concentration  range of about 0.01 to  10 ppm.

                                Faristors
          The discussion of Faristor operating principles  in  the sec-
tion on NO/NOx measurement  is  applicable here.  The Avco effort  (Ref  39)
will be the  first known application of these sensors  to aircraft exhaust
emissions.   Lockheed-California also has  Faristors, but their use  has
not as yet  been  reported.

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                                                                     187
                       Electrochemical Analyzers
          The discussion of electrochemical operating principles in
the-section on CO measurement is applicable here.  There has been no
known attempt to measure the SO. content of aircraft exhausts with such
analyzers.

                             Conductivi ty
          The instruments developed for S0? measurement via conductivity
techniques depend upon the H_0  wet chemical technique.  These instru-
ments have been specifically tailored for ambient, rather than source,
emissions monitoring programs.   They can, of course, be used in a source
measurement program if the source stream is diluted to reduce the SO.
concentration to detectable limits.

                             Spectrometry
          As discussed by Broderick (Ref 59) remote monitoring of SO
                                                                    2
by correlation spectrometry is technically possible but economically
infeasible.  Further development of the technique will be necessary
before it can be employed in a source emissions analysis program.

                               Aldehydes
          Wilson's paper (Ref 8**) and Stahl's survey (Ref 85) contain
thorough  reviews of the procedures for the determination of aldehydes in
air.   All methods for aldehyde determination-- either for total aldehydes
or for individual species (e.g., formaldehyde, acrplein)— depend upon
wet chemical analysis.  The only procedure for continuous aldehyde
analysis  is the Technicon Air Monitor IV-- at a price of $6^00_.  This
monitor makes use of the 3-MBTH wet chemical procedure  (Ref 86) for
total aliphatic aldehydes measured in equivalent formaldehyde units.
(A modified Schiff procedure using rosaniline and dichlorosulfulomercurate
is also available.)

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                                                                     188
                            Total Aldehydes
          A summary of the available methods for total aldehyde
measurement is also given in NREC Report No. 113^ (Ref I) and is not
repeated here.  The most extensively used method for determination of
total water-soluble aliphatic aldehydes (measured as formaldehyde) are
the 3-Methyl-2-benzothiazolone Hydrozone Hydrochloride (MBTH) method.
This procedure was developed by Sawicki (Ref 86) and subsequently
refined by Mauser and Cummins (Ref 69).  In this procedure, 3'MBTH
is reacted with the sample in the presence of ferric chloride in a
sulfamic acid solution to form a blue cation dye that is measured
spectrophotometrically at 628 m^  The procedure is specific for aldehyde
concentrations as low as 2 ppb.   Aromatic amines, heterocyclic imino
compounds, and carbozoles cause-interference with the analysis; however,
since most of these compounds are neither gaseous nor water soluble,
they do not generally interfere  in atmospheric or exhaust gas analysis.
          The disadvantage of the MBTH procedure is that the reaction
is more sensitive to formaldehyde than other aliphatic aldehydes or
branched-chained and unsaturated aldehydes  (Ref 8$).  This causes an
unequal response to each aldehyde which has been reported  (Ref 51)
to be responsible for inaccurate (low) measurement of total aldehydes
in aircraft turbine exhausts.  Further, high ratios of the concentration
of SO- or- olefins to total aldehyde concentration at low (1 ppm)
aldehyde levels may cause errors in the measured results (Ref 8?)•
          Two other techniques for carbonyl measurement are given in
Reference 87.  Their suitability for turbine exhaust measurements are
also discussed.

                       Formaldehyde and Acrolein
          There are a variety of procedures for measurement of individual
aldehyde concentrations; for example,  the ^-hexylresorcinol procedure
exists for acrolein (Ref 69) and the chromotropic acid method is used
for formaldehyde  (Ref 69).  These procedures are applied because  it
is frequently necessary to distinguish between  total aldehydes and  the
two major aldehyde constituents of aircraft exhaust— formaldehyde

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                                                                     189

and acrolein.  This is done in efforts to find correlations between
the odor and irritant properties of engine exhaust gases (Ref 88).
         In the chromotropic acid method, formaldehyde reacts with the
acid to produce a purple-violet monocationic chromogen whose color
intensity (read spectrophotometrically at 580 m^) is proportional to
the formaldehyde concentration.  Fromic acid, dextrose, methanol, phenols,
olefins, and aromatic hydrocarbons and similar compounds that decompose
under the test procedure are also detected; their presence in the
exhaust stream will cause somewhat low measurements.  The technique has
a sensitivity range of 0.01 to 200 ppm.
         Acrolein is also detected by a spectrophotometric procedure.
As discussed by Katz (Ref 65.)., acrolein reacts with ^-hexyl resorcinol
in the presence of mercuric chloride and trichloroacetic acid to
produce a blue-purple color whose intensity can be read by a spectro-
photometer or colorimeter at 605 m/£.  The procedure is quite sensitive
and specific; most organic constituents of the exhaust stream will not
interfere with the determinations.  The technique has a reported
sensitivity range from 20 ppb to 10 ppm.

                             Particulates
          The major problem ascribed to measurement of particulate
emissions from aircraft is one of definition.  All particulates,  large
or small, liquid or solid, emanating from an emissions .source are included
in the Los Angeles County Air Pollution District  (Ref 89)  definition of
particulate matter.  Specifically, they describe particulate matter as
any substance, liquid or solid, except unbound water, that exists in  a
finely divided form at ambient conditions.  Clearly, this definition
means that vapors of low volatility, for example, hydrocarbons, are
counted in two categories— as both hydrocarbons and particulates.
As a result, most aircraft emissions measurement programs are concerned
with particulate matter on a .dry basis; that is, with the liquid
droplets removed from the sample stream or. with the sampling and  collecting
system maintained at a sufficiently elevated temperature to avoid vapor
condensation.

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                                                                     190
          A good example of the discrepancy in the measured results
according to these two definitions is provided in Bristol's paper
(Ref 52) on aircraft gas turbine engine emissions.  Here it is shown
that particulates in the same exhaust stream are as much as 2 to 3 orders
of magnitude higher in concentration if measured by the Los Angeles
"wet" procedure than they are if measured on a dry basis.
          Both solid and liquid particulate emissions are of concern to
air pollution control agencies.  However, in the opinion of the NREC
staff, no particulate measurement device has been developed which
realistically simulates the condensation of vapors as it occurs in an
aircraft engine exhaust plume.  Therefore, the only particulate measure-
ments which have any quantitative significance are those which indicate
concentrations of solid or "dry" particulates.
          NREC Report No. 1134 (Ref ]), the study by Broderick (Ref 59) ~,
and the Los Angeles Source Testing Manual (Ref 89) provide thorough
summaries of the instruments and procedures available for particulate
mass, size, and size distribution measurement.  As a result, only a
summary of the more common types of particle detectors now available
is presented here.
          Collection devices that are most commonly used in monitoring
aircraft particulate emissions are based on filtration and impingement
(wet or dry) techniques.
          Filters remove particles from a gas stream by direct inter-
ception, by inertial collection, by diffusional deposition, by electrical
attraction, and by gravitational attraction.   In a given instrument
one or more of these mechanisms may be employed; details-of these
principles are given in Ref '90.  Filtration schemes are generally applicable
for particles in the 0.1 to 10 micron  (diameter) range; in most cases,
the analysis is completed by direct weighing of the filtrate and filter
medium.  Types of filters and filter holders are discussed in Reference 90;
typical cost of the widely used "Hi-.Vol" sampler which is based on the
direct filtration principle is about $200 to $300.

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                                                                      191

          Impactors or impingers are generally built as cascades to
simultaneously collect and classify particles by both mass and size.
Impactors are less frequently used in aircraft particulate emissions
measurement programs than direct filtration devices; their predominant
application has been with aerosols and dust laden process streams.
Impactors cost from $750 to $2000 with cost dependent upon the stage
requirements and upon the necessity (or lack of necessity) for main-
taining the sample stream at an elevated temperature.
          Mass monitors are devices that allow real-time measurements
of particulate concentration over a size range from 0.01 to 15 microns
and at concentrations up to 100,000 ^^.gms/m .  These instruments
operate by drawing the sample gas through a chamber where the particles
take on an electrostatic charge.  The stream then passes over a
vibrating piezoelectric sensor where an electric field forces the
particles into contact with the sensor.  The resonant frequency of the
sensor is thus reduced in direct proportion to the mass of the adhering
particles; this output signal can be monitored with standard digital
counting equipment (Refs 91 and 92).  Cost of a mass monitor is
$1800 to $2000, a complete system including a monitor,  indicator/printer,
auxiliary vacuum pump, and cabinet,  costs $4000.   One report of the use
of particle mass monitors in an automotive emissions program showed
a deviation of +30 per cent from deposits collected via filtration equip-
ment; this may be due to the presence of organic particles with the
lead particles or to temperature and humidity fluctuations in the diluted
exhaust streams (Ref 93).  Clearly, further development work is still
necessary on this type instrument.
          Other existing detection devices for particulate monitoring
that do not depend upon optical scattering techniques include electrical
mobility analyzers and beta gauge systems.  Electrical mobility analyzers
are used with particles 0.005 to 1.0 microns  in diameter and are based
on the attraction of charged particles to a metal surface of opposing
charge (Ref -59).  Beta gauge systems use a paper tape sampler to collect
particulate matter on a filter; the tape  is then placed between a beta
source and a radiation detector.  The attenuation of the. source energy
is proportional to the particle concentration  (Ref 93).   Both of these

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                                                                      192

instruments are in the prototype stage; the beta guage system has been
successfully employed in an automotive emissions program (Ref 93).
          Microwave laser radar and microwave spectrometers are both
available for measurement of particle size and density in exhaust
streams  (Ref 9^).   Units based on electrostatic precipitation are also
available (Ref 9*t).
          An interesting optical device for particle monitoring  is the
0.1 to 10 micron  (diameter) range is the  integrating "nephelometer"
described by Charlson (Ref 95).  This device measures the scattering
coefficient of light caused by particulate matter in the sample stream
and automatically relates the measurement to particle concentration and
to visibility.   The instrument is so designed that nearly the total
solid angle from full forward to direct back-scattering is observed.
A serious deficiency in the instrument is the needed assumption of a
constant particle size distribution and composition in its calibration
(Ref 96).  The instrument and sampling line can be maintained at a
sufficiently elevated temperature to avoid condensation of the less
volatile matter in the sample stream.  A  nephelometer has recently been
tested with aircraft engines at the Naval Air Propulsion Test Center,
but the  results of the test are unknown (Ref 97)*  Unit cost is about
$5300.
          Most other light scattering or  video scan devices have been
developed primarily for measurement of the size distribution of a sample,
rather than for determination of total particulate concentration.  These
devices  are expensive ($^000 for a sensor to $35,000 for complete systems),
have a limited dynamic range (e.g., 30),  and have an unsatisfactory  lower
sensitivity limit of about 0.1 microns.
          Condensation nuclei counters are used for determination of
the concentration of particulate matter in the 0.001 to 1 micron
(diameter) size range.  Particles of this size are important from an
emissions standpoint since they act as nuclei for the photochemical
smog  reactions.   Further, particulates in this size range are respirable
and thus potential health hazards.   It appears that, the majority of  the
particulate emissions from aircraft engines fall  into this category
(Ref 58) and are  clearly not measured by  convention filtration or

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                                                                     193

impingement techniques.  The basis of operation of condensation nuclei
counters is the ability of condensation nuclei to act as centers for
the condensation of water in a supersaturated environment.  Through the
condensation of the water on the nuclei, droplets are formed of visible
size.  Standard optical techniques are then applied for their detection
and measurement (Ref 98).  Condensation nuclei counters cost in the
vicinity of $6500,with compact portable units available at about $4500.
          Most currently avaiVable condensation nuclei monitors operate
in a range from 0.001 to 0.1 microns with a 20 per cent accuracy.   The
Department of Transportation Systems Research Center  in Cambridge, Mass.
is therefore developing a portable counter to fulfill the need for an
instrument operating in the range from 0.001 to 1 micron  (Ref .59%  The
design goals for this  instrument include the ability to accept sample
streams with concentrations from 10 to 10  particles/cc at input ambient
pressures from 0.05 to 1.0 atm with intake temperatures from -60-deg C
to 200 deg C and with a measured accuracy of 10 per cent across a spectrum
of 10 size ranges.  Reference 59 contains further reference details on
the need for condensation nuclei monitors for aircraft particulate
emissions monitoring.

                                 Smoke
          Three general techniques are applicable for smoke measurement.
These are:
          1.  Subjective analysis where visual comparison of plume
              darkness is made with a graded chart.
          2.  Light extinction where a light meter measures the
              attenuation of a  light source shone directly through a
              sample of the exhaust plume.
          3.   Indirect reflectance where the amount of  light reflected by
              filter paper  through which a fixed volume of the sample
              stream has passed is measured.
In all cases, a smoke  number  is calculated or assigned which relates the
darkness of the plume  to the amount of light absorbed and scattered by
the  smoke.  NREC Report No. 1134  (Ref 1) and the reports  of Shaffernocker
(Ref:99) and Toone  (Ref.100)  contain detailed discussion  of these  techniouo;

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          The first priority of the SAE E-31 Committee was to
develop a method and device for monitoring smoke emissions from
aircraft.   The committee agreed that, "... a stained filter technique
was the most satisfactory even though it missed the desire for a mea-
surement system thai was directly convertible into degree of visible
obscuration (Ref 101)."  This decision led to the SAE ARP-1179<(Ref 55)
which specifies test, sampling (e.g., probe orientation), and analysis
techniques to be followed to insure conformity of smoke measurement in
the aircraft industry.  At the present time, the committee is  considering
modifications to the sampling procedures established in the ARP in light
of information made available since its release.
          Several  instruments have been constructed which conform to
the specifications of ARP 1179-  One unit has a sale price of  $3200
without a sample line or a reflectometer; it is not, however,  generally
ava!1 able.
          As recognized by the E-31 Committee at  its inception, the
stained filter  technique does not  lead directly  into a measure of visi-
bility extinction.  However, correlations have been developed  which relate
the smoke meter reading to the mass concentration of dry particulates  (Ref  102)
and the opacity of the engine exhaust jet (Ref .103).

                                 Odor
          NREC's discussion of the origin and measurement of odor in
aircraft engine exhausts (Ref l.).is still an adequate and appropriate
summary of this emissions problem.  The report by Sullivan (Ref 10^)
the Public Health Service and the papers by Dravnieks (Ref 56) and
Fish  (Ref  105)  are more  recent surveys of  the general  topic  of odorous
emissions; Sullivan's study does contain a brief  section devoted  to
ai rcraft odors.
          Perhaps the most relevant statement about odor is made by
Fish (Ref 105) when he states "... with few exceptions, we  do not
yet know how to apply meaningful  weighting factors to obtain a useful
subjective measurement of odor based on qualitative and quantitative

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                                                                     195

 measures  of  gas  concentration."   Studies  by  Dravnieks  (Ref  106)  and Arthur D.
 Little,  Inc.  (Ref  107)  confirm this  contention by  identifying the composition
 of  odorous  compounds  in diesel  engine exhaust  (by,  for example,  gas chroma-
 to  graphic  separations) but  by failing to develop  adequate  correlations  of
 these concentrations  with a  suitable sensory scale.  Reference 108 contains
 a review'of  federally sponsored  research  on  diesel  engine exhaust odors.
          Not  even this latter type  of analysis has  been undertaken for
 gas turbine  exhausts.   Lozano et al  (Ref  50) do, however, report odor
 dilution  thresholds for turbine  engines as a function  of operating mode
 (power level)  and  engine type.
          As stated in an earlier section, the SAE E-31 Committee is
 planning  to address itself to this emissions problem in the near future.

                      Instruments Under Development
          The principle of operation of the  NO-NOx (and 0 )  chemi-
 luminescence monitor  involves measurement  of the light.energy emitted as the
specimen of  interest  is reacted with another  gaseous specie.  This
principle is by no means restricted to the determination of oxides of
nitrogen and ozone; systems based on the principle have already been
marketed for determination of sulfur dioxide  and hydrogen sulfide
 (Ref 102).   EPA is also developing similar methods  for measurement
of formaldehyde, aromatic hydrocarbons, chlorine, fluorine,  hydrogen
chloride,-arid some metals  (Ref 109).
          A device based on ultraviolet absorption has .been designed
to monitor unburned hydrocarbons in auto exhaust (Ref .110).   In the sample
chamber  the exhaust gas is exposed to UV  radiation.  A sensor tuned to
a wavelength band between  1850 and 2250 Angstroms then measures the
degree of absorption of the radiation by the  sample.  Since olefins
and aromatic hydrocarbons are excellent absorbers in this band (but
oxygen, water, and other common gases are  not), the  instrument is
particularly well-suited for determination of  reactive  hydrocarbons.
          A device for  separating reactive and unreactive hydrocarbon'
 in engine exhaust has al.so been developed  by  Groth and  Zaccardi at
Pratt £• Whitney (Ref.111).  This  unit  is subtractive  in nature;  that is,
chemical absorbents are used  in series with  a  heated FID  to remove

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  the reactive hydrocarbons from the sample.  In this way, the concen-
  tration of the reactive species that participate in the photochemical
  smog reactions can be determ.ined.
            McClatchie (Ref 62)  reports that a single path fluorescent
  NDIR unit similar to that constructed for monitoring CO is under development
  for NO measurement.   The unit promises to have greater sensitivity in
  the lower concentration ranges than conventional NDIR instruments and
  will be free of interference from water vapor and other obscurants.
            Broderick (Ref 59) discusses the'newly-developed technique of
  applying remote Raman spectroscopy to trace gas analysis.   Until
  development of the laser,the procedure was primarily a laboratory curio-
 -sity due to the requirement of lengthy exposure times with high-power
  mercury arc lamps (Ref.  112).  This analysis technique depends on light
  scattering; light absorbed by a molecule is re-emitted at  a shifted
  frequency.  This and the incident  frequency relate to specific character-
  excitation frequencies of the scattering molecule.   If the energy of the
  Raman photons for a particular molecule is known, measurement of the
  scattering relates to the concentration of that specie in  the sample stream.
  Champagne  (Refs kQ and  113) reports a contract between the Aero Propulsion
  Laboratory and Avco Everett for the development of an engineering proto-
  type of a field unit that could be used at either an aircraft test cell
  or at a flight line location.   The two year program will examine the
  technological feasibility of monitoring CO, C02, NO and NOx,  and total
  organics (C-H stretch band)  as they are emitted in aircraft exhausts.
  The first phase of this program is now underway and will determine the
.  appropriate molecular energy bands and potential obscurations (e.g.,  CO by CO
  or CO  by CO) at the elevated, temperatures (1200 to 1800 deg.F)  of interest.
             Hinkley and  Kelley  discuss  (Ref. 11A)  the development  of
  tunable  semi-conductor  diode  lasers which  show  promise  in  the creation
  of  extremely  sensitive  and  accurate NDIR  instruments.  As  discussed  by
  Broderick  (Ref 59)  such diodes could  be "tuned" to specific  wavelengths
  to  permit  monitoring of such  species  as  the  individual  components  of the total
  hydrocarbon  emission. An instrument specific to NO and which depends on
  tunable  infrared  radiation  from a Raman  spin-flip  laser has  been  reported

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                                                                     197
to detect NO contentrations in air samples at concentrations as low as
0.01 ppm (Ref 115).
          LIDAR or Light Detection and Ranging systems have been proposed
as atmospheric probes to measure and detect particulate concentrations in
the atmosphere.  These instruments depend on lasers as power sources and
on back scattering measurements to determine particle size distribution
and number density.  LIDAR is a tool for remote monitoring programs;
one drawback to its use is the necessity to make a priori assumptions
pertaining to particle size distribution and.index of refraction for
the purpose of instrument calibration.  Reference •)16 contains a review
of the technique and of its potential application as a pollution
monitoring tool.
          Dix et al (Ref 11?) discuss the use of a mass spectrometer as
a probe for studying the chemical  kinetics of the formation of oxides of
nitrogen in a simulated gas turbine combustor.   The' probe is suitable
                                           -3      -4
for* measurement of mole fractions in the 10   to 10   range, but
requires further engineering development before use as a mobile monitor
for engine emissions.

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