A/C No. 17F
                        Unned Sia:es                Off ice of                    November  16, 1982
                        Environmental Protection         Air. Noise and Radiation           Paee  1 of  17
                        Agency                   Washington. DC 20460
&EPA            QMS
                       Advisory
       SUBJECT:  General Criteria for the Carryover and  Carry-Across of Certification
                Data and the Carryover of Fuel Economy  Data for Light-Duty Vehicles
                and Light-Duty Trucks
       I.     Purpose

             The  purpose of this advisory circular (A/C)  is  to set forth EPA's policy
       regarding  the use of certification data in more  than  one category or
       subcategory of vehicles of the same model year (known as "carry-across") and
       the  use  of data from previous model years' certification vehicles (known as
       "carryover").  A/C No. 17E is superseded beginning with the 1983 model year.

       II.    Background

             A.   General Background

                 40 CFR 86.082-24(f) provides that the  Administrator may accept data
       from a vehicle for which certification has previously been obtained or for
       which all  applicable data required under Section 86.082-23 have previously
       been submitted and which is similar to another emission-data or
       durability-data vehicle selection.  This provision is the basis for carryover
       and  carry-across and permits manufacturers to obtain  certification without
       unnecessarily incurring the costs and delays of  building and testing
       certification vehicles.

             B.   Recent Revisions

                 1.  Although some interaction between  evaporative and exhaust
       emission levels is likely, the amount of interaction  is not expected to be
       large enough to significantly affect the deterioration of exhaust emission
       control  systems.  Therefore, the evaporative emission family and control
       system restrictions of.A/C No. 17E, paragraphs VI.A.3.b and c, have been
       deleted.

                 2.  EPA initiated the voluntary Abbreviated Certification Review
       Program  in a letter to manufacturers dated December 15, 1978.  In Attachment A
       of the letter, EPA said that manufacturers may decide in lieu of the
       Administrator the appropriateness of using emission data from previously
       certified  vehicles to represent test results of  similar emission-data and
       durability-data vehicles in lieu of testing said vehicles.  The abbreviated
       certification review program procedure was formally adopted in 40 CFR
       86.080-12 on April 17, 1980.  Manufacturers have been routinely making their
       own  carryover decisions, subject to EPA audit, since  that time.

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                  U.S. Environmental  OANR/MS           A/C NO.   17F
                  P-otection Agency                          PAGEJ
           3.  In order to facilitate the efficient  carryover of durability
 data based on equivalence or superiority, a list of vehicle differences and
 specific data requirements has been added to Section IX.   This will allow
 manufacturers to approve durability carryover based on  equivalence or
 superiority in certain limited situations.

           4.  EPA policy concerning test weight  intervals  was established in a
 memorandum to Certification Branch members  dated April  24, 1979.  The
 memorandum stated that emission-data carryover would not be jeopardized if a
 vehicle had been tested at a higher test weight  in  a previous year and the
 request for carryover was to represent a vehicle at a lower test weight.  The
 inertia weight class restriction of A/C No.  17E  paragraph  VI.A.4.d has been
 deleted to reflect'this policy.

           5.  On September 25,  1980,  EPA published  regulations in 40 CFR
 86.084-28(b)(4)  that allow manufacturers to  design  their own testing
 procedures for determining emissions  deterioration  factors for light-duty
 trucks starting  with the 1984 model year.   Under these  regulations,  the
 manufacturer is  responsible for determining  the  applicability of carryover of
 deterioration factors for light-duty  trucks.   As in the past, carryover
 guidelines established for light-duty vehicles may  be used by the manufacturer
 for light-duty trucks where applicable.

           6.   EPA sent a letter to manufacturers dated July 1,  1981  which
 contained  Certification Program Policy Changes including several changes to
 A/C No.  17E.   Paragraph VI.A.S.d was  changed  to  allow equivalent test weight
 to  increase  by 500 pounds for durability-data  carryover.  Paragraph  VI.A.S.f
 was deleted  to remove the road-load horsepower constraint for durability-data
 carryover.   Paragraph VI.A.5.b was changed to  allow emission-data carryover of
 back-to-back running change testing.   This A/C has  been revised to reflect
 these  policy  changes.

           8.   On  October 13,  1981  EPA published  regulations in  40 CFR
 86.082-26(a)(3)(i)(A)  and (ii)(A)  that allowed emission-data  vehicles to
 accumulate more  than 4,250 miles  but  required  the fuel economy  data  to be
 factored after 6,200 miles.   Paragraph V.A.6 of  this advisory circular was
 added  to ensure  that any  data generated  by a fuel economy data  vehicle which
 was  carried over  to  fulfill emission-data requirements would  also be  factored.

 III.  Applicability

      This advisory  circular  is effective immediately and is  applicable to
 1983 and later model year light-duty  vehicles and light-duty  trucks.

      NOTE;   To avoid  repetition of phrases such as  "prior  model  year,"
 "current model year,"  and  "year for which certification  is  sought," general
 applicability  references  are made  to model years 1982 and 1983.   These
 references do not limit the applicability of this A/C.  In  applying this
 circular to other model years, 1983 shall be considered  to  have  the same
meaning as "year for which certification is sought," and 1982 to  mean "year in
which carryover data were generated," or "prior model year."

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                      U.S. Environmental  OANR/MS            A/C NO..
                                                                                  17F
BrEnF\             P-otection  Agency                          PAGE_L_ OF
      IV.    Relationship Between Emission Data Carryover and  Fuel  Economy Data
            Carryover

            A.   Although the carryover of certification data  is  treated separately
      from the  carryover of fuel economy data in this A/C,  the approval of fuel
      economy data  carryover depends on the acceptability of  emission data
      carryover. Conversely, in some cases, emission data carryover may not be
      approved  in light of information obtained while generating new fuel economy
      data.   For these  reasons, neither emission data carryover  or fuel economy data
      carryover will be approved nor denied until the acceptability of both of these
      sets of data  is determined.

            B.   In  general, three conditions can exist relating  to emission data
      carryover and fuel economy data carryover, as follows:

                1.  If  both emission data and fuel economy data  carryover criteria
      are  met,  emission data and fuel economy data carryover  will  be approved.

                2.  If  emission data carryover is found to be unacceptable, neither
      emission  data nor fuel economy data carryover will be approved.

                3.  If  the emission data carryover criteria are  met, but the fuel
      economy data  are  found to be unacceptable for carryover, fuel economy data
      carryover will not be approved and new fuel economy data will be required.
      Emission  data carryover will not be approved at this time.  If the new fuel
      economy data  are  acceptable and and the fuel economy data  vehicle meets  the
      1983 emission standards, emission data carryover will be approved.

            C.   A flow  chart depicting a general carryover evaluation procedure is
      attached  to this  A/C.

      V.    General Criteria for Carryover of Exhaust Emission Data

            A.   An  initial determination as to the acceptability of the proposed
      carryover data will be based in part on such considerations  as the similarity
      of test results between the manufacturer's and EPA1s facilities, special
      problems, or  marginal emission performance encountered  during 1982
      certification.  The ultimate determination will be made as follows:

                1.  The 1983 certification test vehicle selection  will be designated
      just as if carryover had not been requested.

                2.  The test vehicle selection for 1983 will  be  compared with  the
      vehicle which generated the proposed carryover data.

                3.  Carryover durability data will be accepted if  the  1982
      durability-data vehicle:
17

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                 U.S. Environmental  OANR/MS            A/C NO.
                 P-otection Agency                          PAGE_$	OF 2L_
              a.  Qualified to be grouped in Che same engine family! as the
durability-data vehicle designated for 1983—vehicles not qualified to be
grouped in the same family may be evaluated under the provisions of Section IX,

              b.  Was equipped with the same exhaust and crankcase emission
control systems as the durability-data vehicle designated for 1983—vehicles
not equipped with the same control systems may be evaluated under the
provisions of Section IX,

              c.  Was tested at the same, heavier,  or no more than 500 pounds
lighter equivalent test weight as the durability-data vehicle designated for
1983,

              d.  Was generally representative of the durability-data vehicle
which was designated for 1983 model year certification in terms of other
parameters judged to be significant by EPA (e.g., engine displacement,
auxiliary emission control devices, etc.),

              e.  Had interpolated test results which could comply with the
provisions of 40 CFR 86.082-28, and

              f.  Had all emission-related scheduled maintenance items
performed at the same or less frequent mileage interval as is scheduled for
the 1983 vehicles for which carryover is sought.  Maintenance items which were
scheduled to be performed on the 1982 vehicle on an "inspect and perform if
necessary" basis, but were not performed as a result of the inspection, may
generally be eliminated from the 1983 maintenance schedule (if justification
is provided) without jeopardizing durability carryover.  Less frequent 1983
model year maintenance also may be approved if the manufacturer demonstrates
that such maintenance results in equivalent or superior emission control
performance (see Section IX).

          4.  Carryover emission data normally will be accepted if the 1982
emission-data vehicles

              a.  Qualified to be grouped in the same engine family-'- as the
fimission^data vehicle designated for 1983,

              b.  Qualified to be grouped in the same evaporative emission
family^ as the emission-data vehicle designated for 1983—vehicles not
qualified to be in the same evaporative emission family may be evaluated under
the provisions of Section IX,

              c.  Was equipped with the same exhaust, evaporative3, and
crankcase emission control systems as the emission-data vehicle designated for
1983,

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                U.S. Environmental  OANR/MS            A/C  NO.JH
                Protection Agency                           PAGE  5   OF  i?
              d.   Was  tested at the  same or heavier equivalent test weight  and
had the same transmission configuration (i.e., manual, automatic,
serai-automatic,  number of forward gears, overdrive [if used during FTP],
torque converter multiplication ratio, stall speed, and shift calibration)  and
N/V ratio (within three percent in any of the forward gears),

              e.   Used a shift procedure which, for any upshifting sequence
(e.g., shifting  from second  to third), differs by no more than 3 raph from the
shift procedure  recommended  by the manufacturer (in accordance with 40 CFR
86.128-79) for the emission-data vehicle designated for 1983 (see paragraph
4.d, above),

              f.  Differed from the  emission-data vehicle selected for 1983
nnly in ways (e.g., calibration differences) in which, in EPA's technical
judgment, would  cause the  1983 vehicle  to have equivalent or superior emission
characteristics,

              g.  Had a road-load horsepower value of at least 90 percent of
that road-load horsepower  setting designated for the  1983 model year, and

              h.  Had emission  test  results which would comply with the 1983
standards after the applicable deterioration factor has been applied.

          5.  Carryover of  data from running change vehicles will be accepted
if  the running change vehicle meets  the criteria of paragraph 4 above.

          6.  Carryover of  data from fuel economy data vehicles to satisfy
certification emission-data  requirements will  be accepted if:

              a.  The vehicle meets  the criteria of paragraph 4 above, and

              b.  The fuel economy  data has been factored according to 40  CFR
86.082-26(a)(3)(i)(A) and (it)(A).   (If the data has  been previously submitted
unfactored, it should be factored  and resubmitted  as  a new  test.)

      B.  If, based on the above  criteria  (including  the initial  determination
regarding the acceptability of  the proposed carryover data), exhaust emission
carryover data would satisfy 1983 model year  testing  requirements, EPA may
allow its use.  In  the event carryover of  exhaust  emission  durability data  is
granted,  the exhaust emission deterioration factor will  be  used to determine
if  emission-data  vehicles,  proposed running changes,  or model additions meet
the exhaust emission standards.

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                U.S. Environmental  OANR/MS            A/C NO.  17F
                P-otection Agency                          PAGE_L_ OF IL
VI.   Criteria for Carryover of Evaporative Emission Data

      For evaporative durability data,  the manufacturer is responsible for
determining the applicability of carryover of the evaporative deterioration
factor.  For evaporative emission data,  an initial determination as to the
acceptability of the proposed carryover data will be based in part on
considerations including the similarity of test -results between the
manufacturer's and EPA's facilities or  special problems encountered during the
1982 certification program.  The ultimate determination will be made as
follows:

      A.  The 1983 certification test vehicle(s) will be designated just  as if
carryover had not been requested.

      B.  The evaporative emission control system of the test vehicle(s)
selected for 1983 will be compared with the respective 1982 system.

      C.  Carryover evaporative emission data will be accepted if the 1982
emission-data vehicle was tested for evaporative emissions, and;

          1.  Qualified to be grouped in the same evaporative emission
family  as the emission-data vehicle designated for 1983,

          2.  Was equipped with the same exhaust, evaporative-*, and
crankcase emission control systems as the emission-data vehicle designated for
1983,

          3.  Differed from the emission-data vehicle selected for 1983 only
in ways (e.g., calibration differences) which, in EPA's technical judgment,
would cause the 1983 vehicle to have equivalent or superior emission
characteristics, and

          4.  Had emission test results which would comply with the 1983
standards after the deterioration factors have been applied.

VII.  Criteria for Use of Certification Carry-Across Data

      A.  The criteria for determining  if  two  (or more) vehicles are
sufficiently similar to permit the carry-across  (applying data to vehicles
from more than one family or system within  the same model year) of
certification data, for either exhaust  or evaporative emissions, are that the
data shall meet the appropriate criteria used  to  judge the acceptability of
data for carryover purposes.

      B.  Two situations exist for which the  use  of carry-across data is
feasible:

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ACDA             U.S.  Environmental  OANR/MS            A/C NO.  17F
S>tnF\             P-otection  Agency                           PAGE  1   OF
                 1.   Light-duty  vehicles and trucks;  Although the standards for
       gasoline-fueled  and  diesel  light-duty vehicles differ from the standards of
       the corresponding  types of  light-duty trucks, some manufacturers have elected
       to employ the same emission control techniques on passenger cars and
       light-duty trucks.   Because the emission test procedures for gasoline-fueled
       light-duty vehicles  are the same as those for light-duty trucks (except for
       the horsepower calculations),  as are the emission test procedures for diesel
       light-duty vehicles  and light-duty trucks, the data generated from a
       gasoline-fueled  LDV  (or LDT) may be used to satisfy data requirements for a
       LDT (or LDV), provided the  appropriate carryover criteria provided in this A/C
       are met.

                 2.   Evaporative emission testing within an evaporative emission
       family;  The  evaporative  emission regulations for LDV's and LDT's (41 FR
       35626) established the evaporative emission family concept.  This concept is
       intended to require  evaporative emission testing of only those test vehicles
       which represent  unique evaporative emission control systems.  Carry-across of
       data will be  approved if, under the provision of A/C No. 59, the individual
       evaporative emission families  were eligible to be grouped together as a single
       evaporative emission family and if the minimum data requirements of the
       combined family  are  represented, in whole or in part, by the data for which
       carry-across  is  requested.  Since LDV and LDT evaporative emission families
       must be separate,  if two  emission families differ only in that one is for
       LDV's and one is for LDT's, carry-across of data will be acceptable.
       Additional data  requirements of the combined family, of course, would also
       have to be met before certification can be granted.

       VIII. Requesting the Use  of Carryover and Carry-Across Certification Data

             If a manufacturer intends to use carryover or carry-across data to
       satisfy the 1983 model year certification requirements, EPA should be notified
       in the cover  letter  accompanying the 1983 application for certification.
       Then, the manufacturer must provide the test data which the manufacturer
       proposes to use  and  a complete list of differences between the vehicle(s)
       specified for 1983 and the  vehicle(s) which generated the data for which
       carryover is  being requested.  In addition, the manufacturer should include a
       complete description of the vehicles (whether durability-data, emission-data,
       fuel economy,  or running  change vehicles) which generated the data as a.
       supplement to the  application  (relevant pages from the 1982 application are
       usually acceptable for this purpose) or should refer to the appropriate pages
       in the 1982 application.

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                 u-s- Environmental  OANR/MS            A/C NO.  17F
                 P-otection Agency                           PAGEJ*
 IX.    Other Demonstration of Certification Carryover or Carry-Across
       Applicability

       If a 1982 vehicle does not qualify for carryover or carry-across under
 Sections V, VI, VII, and VIII outlined above, but the vehicle difference(s)
 would  indicate that the 1983 model year vehicle will have equivalent or
 superior performance, data  from the 1982 model year vehicle may  still be
 acceptable upon demonstration by the manufacturer of the equivalence or
 superiority of the proposed configuration through use of emission data or
 other  information to be evaluated on an individual basis*

       The following list of examples is provided to facilitate the efficient
 use of this option regarding the carryover or carry-across of durability
 data.  The list contains examples of vehicle differences which have either
 been previously approved by EPA or which, in EPA's opinion,  are  likely to
 result in equivalent or superior emissions durability.  The list is not
 intended to limit the use of this option.  EPA will continue to  evaluate
 requests for vehicle differences not listed below on an individual basis.  In
 order  for the manufacturer  to approve durability carryover under the
 Abbreviated Certification Review Program protocols for one or more of the
 changes listed below, all of the other engine family or emission control
 system parameters listed in 40 CFR 86.082-24(a)(2) or Advisory Circular No.
 20-B must be the same.  The manufacturer is allowed to approve durability
 carryover if one or a combination of the vehicle differences listed below
 exist.

      Regarding manufacturer approval of carryover based on equivalence or
 superiority for items listed below,  the basic philosophy is  that if a
 particular system has been certified its physical durability and emissions
 stability have been sufficiently demonstrated for purposes of preproduction
certification.  If, in addition, catalyst thermal degradation is not
 significantly increased, EPA believes durability carryover can be approved
without significant risk to emissions performance.  Catalyst temperature,
while not the sole indicator of emissions performance,  is in EPA's opinion a
 significant indicator.  Since catalyst temperatures provide  objective criteria
for assuring that thermal degradation of the catalyst does not increase, the
manufacturers can be allowed to approve carryover.  For new or unproven
systems,  however, EPA has no assurance that carryover can be approved without
significant risk to emissions performance.   Therefore,  manufacturers must
continue to submit to EPA requests for carryover of data to  new systems or to
systems that EPA has not determined  are likely to result in  equivalent or
superior performance as outlined below.

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                U.S.  Environmental  OAIMR/MS            A/C NO.   17F
                Protection Agency                           PAGE.
      In certain instances,  EPA expects that manufacturers will want to
carryover data to a vehicle  using systems or components that are not identical
to ones that have been used  in a family that has been previously certified.
In those cases where a particular system or component differs by more than
calibrations from one that has been used previously, it is the manufacturers'
responsibility to assure  that whatever minor differences exist will not
adversely affect emissions deterioration.  If the manufacturer does not have
an adequate basis and associated documentation for such a determination,
carryover should not be approved.  EPA intends to exercise its option to audit
and review data or other  information utilized in making such determinations.
This audit process will be facilitated if the manufacturer prepares a list of
all differences (other than  calibrations) between the system or component
intended for production and  the one that was previously used in a certified
family and addresses the  durability impact of each difference.  In addition,
EPA may confirm the validity of the manufacturers' determinations through its
in-use vehicle testing programs which could result in recall and denial of
future carryover of particular data.

      A.  Engine Displacement

          Carryover of durability data from a larger displacement engine to
one that is more than 50  cubic inches or 15 percent smaller may be approved by
the manufacturer if:

          1.  the engines are otherwise qualified to be in the same engine
              family in terms of the engine parameters specified in 40 CFR
              86.082-24(a)(3), and

          2.  catalyst thermal degradation does not increase significantly^
              due to this change.

          If the block configuration, valve locations, or cylinder bore
center-to-center dimensions  are not the same, the manufacturer must submit a
request for carryover with specific information, catalyst temperature data,
and any evidence of engine out emissions stability (may include bench test
data,  etc.) to EPA for evaluation.

      B.  Fuel System

          Case 1.  The number of carburetors, number of Venturis, or principle
of carburetor operation (e.g., simple venturi, air valve, constant depression)
may be deemed equivalent  for durability purposes and the manufacturer may
approve durability carryover ifJ

          1.  the carburetor model intended for production has been used in a
              family that has been previously certified^ by that manufactuer
              and

          2.  catalyst thermal degradation does not increase significantly^
              due to this change.

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                U.S. Environmental  OANR/MS            A/C NO.  I?F
                P-otection Agency                          PAGEJ£
          Case 2.  Carryover of durability data from  a  vehicle using one or
more carburetors to a vehicle using any electronic  timed or pulsed fuel
injection system may be approved by the manufacturer  if*

          1.  the fuel injection system design intended for production has
              been used in a family that has been previously certified5 by
              that manufacturer and

          2.  catalyst thermal degradation does not increase significantly due
              to this change.^

          Case 3.  Carryover of durability data from  a  vehicle using throttle
body fuel injection to a vehicle using electronic timed or pulsed multipoint
intake manifold fuel injection may be approved by the manufacturer ifi

          1.  the fuel injection system design intended for production has
              been used in a family that has been previously certified5 by
              that manufacturer and

          2.  catalyst thermal degradation does not increase significantly due
              to this change.^

          For any other fuel system changes that could  not normally be grouped
in the same engine family, the manufacturer must submit a  request for
carryover with specific information, catalyst temperature  data, and any
evidence of physical durability or engine out emissions stability (may include
bench test data, etc.) to EPA for evaluation.

      C.  Catalyst

          Case 1.  The manufacturer may approve the carryover of durability
data for any of the following differences;

          1.  change in general catalyst location away  from engine  (downstream
              movement,  e.g., from engine compartment  to  underfloor area).

          2.  increase in catalyst volume (in excess  of 15 percent  of  largest
              volume) at the same or higher noble metal loading  (g/ft3 and
              proportion of active constituents).

          3.  increase in active material loading of  any  or all  noble  metals
               (proportion of active constituents may  only  be changed  by
              increasing the load of particular noble metals—decreases in
              active material  loadings must be evaluated  under  the
               "essentially equivalent" provisions of  A/C  No.  20B).

          Case  2.  Carryover of durability data to a  vehicle  using  different
basic catalyst packaging  (e.g., materials, technique  of containment and
restraint,  and general method  of construction) or substrate construction
technique («.g., extruded, laid-up, formed) may be approved  by  the  manfacturer
ifi

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                                                                             17F
                U.S. Environmental  OANR/MS            A/C NO.
                P-otection Agency                           PAGE 11   OF i?
          1.   the  basic catalyst packaging or substrate construction  technique
              intended for production has been used in a family  that  has  been
              previously certified5 by that manufacturer and

          2.   catalyst thermal degradation does not increase significantly due
              to this change.^

          For any  other catalyst changes that could not be grouped in the same
engine family and  emission control system under A/C 20B, the manufacturer must
submit a request for carryover with the specific information, catalyst
temperature data,  and evidence of physical durability and emissions stability
to EPA for evaluation.

      D.  Air Injection

          Case 1.   Carryover  of durability data to a vehicle which differs  in
general location of injected  air, general method of driving air pump, or
modulation of secondary air flow rate may be approved by the manufacturer if;

          1.   the  basic air injection system intended for production,
              including general location of injected air, general method of
              driving air pump, or modulation of secondary air flow rate, as
              applicable, has been used in a family that has been previously
              certified5 by that manufacturer and

          2.   catalyst  thermal degradation does not increase significantly due
              to this change.^

          Case 2.   Pump air injection and pulse air injection may be deemed
equivalent for durability purposes and durability carryover may be approved by
the manufacturer if:

          1.   the  basic air injection system intended for production,
              including general location of injected air, general method of
              driving air  pump, or modulation of secondary air flow rate, as
              applicable,  has been used in a family that has been previously
              certified5  by that manufacturer and

          2.  catalyst  thermal  degradation does not increase significantly due
              to this change.^

          Case 3.   Carryover  of durability data from  a  vehicle with no air
injection to a vehicle  with either pump air injection or pulse air injection
may be  approved by the  manufacturer  if4

          1.  the basic air  injection  system  intended for  production,
              including general location  of  injected  air,  general method of
              driving  air pump, or modulation of secondary  air flow  rate, as
              applicable,  has been  used  in a  family  that  has been  previously
              certified5 by  that  manufacturer and

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                 U.S. Environmental  OANR/MS           A/C NO.   I?F
                 P'otection Agency                          PAGE_il_ OF J_7
          2.  catalyst thermal degradation does not  increase significantly due
              to this change.^

          For any other air injection changes that could  not be grouped in the
same control system under A/C No. 20B, the manufacturer must submit a request
for carryover with specific information,  catalyst temperature data, and any
evidence of physical durability or emissions stability  (may include bench test
data, etc.) to EPA for evaluation.

      E.  Exhaust Gas Recirculation

          Carryover of durability data to a vehicle  which differs in general
location of exhaust gas pickup, general point of exhaust  gas introduction, or
general method of modulating quantity of  EGR may be  approved by the
manufacturer if;

          1.  catalyst thermal degradation does not  increase significantly due
              to this change^ and

          2.  the basic EGR system Intended for production, including general
              pickup location, general introduction  point, and general
              modulation method, has been used in a  family that has been
              previously certified^ by that manufacturer. (EPA has noted
              that other items such as EGR valve location and pintle design,
              EGR flow passageway design,  cooling method  design, transducer
              designs, diaphram materials, etc., can also affect EGR system
              deterioration.  The manufacturer should document that any
              changes to these items do not cause increased EGR system
              deterioration.)

          For any other EGR changes that  could not be grouped in the same
control system under A/C No. 20B, the manufacturer must submit a request with
specific information, catalyst temperature data, and evidence of physical
durability and emissions stability (may include bench test data) to EPA for
evaluation.

      F.  Electronic Control Systems

          While Electronic Control Systems are not listed among the engine
family or emission control system determinants in A/C No. 20B, EPA has noted
that certain aspects of these systems can affect emissions durability and
offers the following as a guideline for assuring that the 1982 durability-data
vehicle was generally representative of the 1983 durability-data vehicle.
Different electronic control systems may  be deemed equivalent for durability
purposes and the manufacturer may approve durability carryover under the
following conditions:

          1.  The sensor and controller designs intended  for production have
              been used in a family that  has been previously certified5 by
              that manufacturer.

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                U.S. Environmental  OANR/MS            A/C NO.  I?F
                P-otection Agency                           PAGE_il_ OF_il
          2.  The use of a malfunction warning  system may not be deleted.

          3.  The following parameters may  not  be deleted;
              a.  Electronic Spark Control
              b.  Sensing of EGR Valve Position or Flowrate

          4.  The following parameters may  not  be added or deleted:
              a.  Sensing of Exhaust  Gas  Oxygen or Content
              b.  Sensing of Mileage  (or  inferred mileage in the form of Time)
              c.  EGR Control
              d.  Feedback Fuel Control

      Requests for carryover that do  not  meet the above conditions may be
submitted to EPA for evaluation.   The request should include specific
information and evidence of physical  durability and emissions stability (may
include bench test data, etc.)

X.    General Criteria for Carryover  of Fuel Economy Data From Vehicles for
      Which Certification Carryover is Requested

      A.  When requesting approval to use emission data generated by vehicles
selected in accordance with the provisions  of 40 CFR Part 86 for carryover
certification, the manufacturer should be cognizant of the fact that the EPA
approved fuel economy values must also be considered as part of the request.
These fue] economy data, or the fuel  economy data generated in accordance with
the criteria set forth in paragraph X.F,  will be used in the fuel economy data
base.

      B.  The general criteria  which  EPA  will use to determine the
appropriateness of any carryover  request  are outlined in Section IV.  For fuel
economy carryover purposes,  any certification vehicle for which emission
carryover is requested and which  satisfies  the  criteria in Section V of this
A/C also satisfies the provisions of  40 CFR 600.007-80(a) for vehicle
acceptability.

      C.  A carryover request which does  not satisfy the general criteria set
forth in Section V of this A/C  will not be  considered for either emission-data
carryover or fuel economy carryover and,  therefore, a new emission-data
vehicle will be required.

      D.  Once the vehicle acceptability  has been determined, the 1982 data
will be evaluated as to representativeness  for  1983 by determining if (as a
minimum):

          1.   The 1982 vehicle  was tested at the same or higher equivalent
test weight,

          2.   The 1982 vehicle  was tested at the same or higher road load,

-------
                U.S. Environmental  OANR/MS            A/C NO. 17F
                Protection Agency                          PAGE.
          3.  The 1982 vehicle was shifted in a manner consistent with the
shift procedure guidelines set forth in A/C No. 72 or at  speeds which would be
expected to understate the fuel economy performance,

          4.  The 1982 vehicle differed from the 1983 emission-data vehicle
selected only in ways which, in EPA's technical judgment, would cause the 1983
vehicle to have equivalent or superior fuel economy characteristics.

      E.  For those certification and fuel economy data judged by EPA to be
representative, the fuel economy data generated by the certification vehicle
will be used, that is, carryover of data (both fuel economy and certification)
will be approved.  In fact, data from a certification vehicle which satisfy
the criteria for acceptability and representativeness must be used in the fuel
economy program.

      F.  In those cases where the certification data satisfy the criteria of
Section V, but the fuel economy are judged by EPA to be unrepresentative
because they would be expected to overstate the 1983 fuel economy values, or
there is a degree of uncertainty regarding the evaluation of
representativeness in paragraph X.D above, the manufacturer will be required
to test a 1983 fuel economy data vehicle (FEDV).  If any  of the emission
levels from the FEDV exceed the emission standards with the appropriate
deterioration factor applied, then the data from the FEDV are unacceptable and
the request for carryover of 1982 emission data will be denied.  If the data
meets the standards and the requirements of 40 CFR 600.007-80 then, because
the FEDV is a 1983 vehicle tested in accordance with the  1983 test procedures,
the FEDV will satisfy the criteria of acceptability and representativeness.
However, the data must still satisfy a fuel economy reasonableness check.

      G.  If the fuel economy data from the 1983 FEDV are judged to be
reasonable, the data will be used.  Also, if the data from  the 1983 FEDV
confirm the fuel economy data from the 1982 emission-data vehicle, both sets
of fuel economy data will be used.  In both cases, the  emission  results from
the 1982 emission-data vehicle will be used.  That is,  the carryover  request
(both fuel economy and emission-data) will be approved.

      H.  If the fuel economy data generated by the 1983  FEDV at the
manufacturer's facility are judged to be unreasonable,  the  vehicle will be
subjected to EPA confirmatory testin?   If the emission data, generated at EPA
in accordance with the provisions of  J CFR 86.081-29,  do not meet the
emission standards with the appropriate deterioration factor applied,
carryover will be denied and a new emission-data vehicle  will  be  required.   If
the emission data from the  1983 FEDV meets the emission standards,  the  1983
emission-data carryover request will be granted.  However,  the  fuel economy
data must still satisfy the reasonableness criteria.

      I.  Once the fuel economy data generated at EPA satisfy  the
reasonableness check, the fuel economy data from the 1983 FEDV  will  be  used  to
satisfy the 1983 fuel economy carryover request and emission data  carryover
will be granted, as described in paragraph X.G.

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                U.S. Environmental  OANR/MS            A/C NO.   I?F
                Protection Agency                           PAGE is   OF 1?
XI.   General Criteria for Carryover of Fuel Economy Data  from Vehicles Other
      Than Those for Which Certification Carryover is Requested'

      A.   A request for carryover of fuel economy data from  vehicles other
than those for which certification carryover is requested  must be submitted
with an FEDV package indicating that the data are from a prior model year.

      B.   Vehicles other than those for which certification  carryover is
requested must satisfy the criteria set forth in Section V of this A/C to be
considered for fuel economy carryover.

      C.   Since the vehicles which generated these data have previously
satisfied the vehicle acceptability and data reasonableness  criteria, the data
need only satisfy the representativeness criteria (paragraph X.D of this A/C).

      D.   Data which satisfy all of the criteria will be included in the fuel
economy data base in accordance with the provisions of 40  CFR 600.008-77(b).

      E.   Any vehicle which does not satisfy the certification carryover
criteria and/or data which do not satisfy the representativeness criteria will
cause the carryover request to be denied.
                      Director, Office of Mobile Sources
Attachment

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                U.S. Environmental  OANR/MS            A/C NO.   17F
                Protection Agency                           PAGE 16   OF 17
                                   ENDNOTES
1.   "Qualified to be grouped in the  same  engine family" means that the
     current year vehicle and the vehicle  which generated the proposed
     carryover data must be identical in all  the aspects listed in A/C No.
     20B, Sections D, E, F (four-stroke, two-stroke, or rotary engines
     respectively).

2.   "Qualified to be grouped in the  same  evaporative emission family" means
     that the current year vehicle and the vehicle which generated the
     proposed carryover data must be  identical in all the aspects listed in
     A/C No. 59, Section D.

3.   The same basic evaporative emission control system as specified in A/C
     No. 59, Section E.

4.   It is the manufacturer's responsibility  to assure that an increase in
     catalyst temperature will not result  in  increased thermal degradation  of
     the catalyst.  If the manufacturer has any reason to suspect that thermal
     degradation of the catalyst will increase significantly, carryover may
     not be approved.  EPA believes that thermal degradation of the catalyst
     is not likely to increase if catalyst temperatures do not increase.  EPA
     intends to look more closely at  those cases where catalyst temperatures
     increase significantly.  Criteria are offered below as a guideline to
     determine If catalyst temperatures are significantly affected.  These
     criteria allow small increases in time and temperature to account for
     measurement variability.  A manufacturer may determine that other
     criteria are more appropriate for establishing the acceptability of
     carryover for its designs*  The  manufacturer should document the basis
     for Its determination that thermal degradation of the catalyst will not
     increase significantly.  If a manufacturer believes that the following
     guideline is not appropriate for a particular situation and can document
     that thermal degradation of the  catalyst will not increase even though
     these criteria are not met, durability carryover may still be approved.
     However, when the following criteria  are not met, the manufacturer should
     notify EPA in writing at the time the carryover decision is made.  This
     will allow most timely EPA audit of the  manufacturer's carryover
     decision.  The amount of time spent in the following temperature
     intervals is not increased by more than  three percent or 60 seconds,
     whichever is greater, during the mileage accumulation cycle
     (approximately 2 hour cycle) unless there is a corresponding decrease  in
     time at a higher temperature interval.   The temperature intervals are
     601°C to 650°C, 651°C to 700°C,  701°C to 750°C, and 751°C to 800°C (other
     intervals within this range may  be appropriate, the 60 second tolerance
     applies to a 50°C interval).  If maximum temperatures are above 800°C,
     the maximum temperature is not increased by more than 2 percent and
     amount of time above 800°C is not increased by more than two percent or
     30 seconds, whichever is greater.  Whenever possible, the impact of a

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                 U.S. Environmental  OANR/MS            A/C NO.  i7F
                 Protection Agency                           PAGE 1?  OF 1?
     change on catalyst  temperatures should be evaluated on a single vehicle,
     preferably the  original durability-data vehicle.  If the original
     durability-data vehicle is not available, the highest selling
     configuration from  either of the model years is preferred.   If it is not
     practical to evaluate  the change on a single vehicle, other vehicle
     differences which could affect catalyst temperatures should be
     minimized.  Again,  configurations representing highest sales from each
     model year should be used if practical.  Thermocouples should be located
     to provide accurate measurement of maximum temperatures.  Each
     manufacturer should obtain a description of such location from his
     catalyst  supplier and  retain this with the rest of the documentation.   If
     this is not possible,  thermocouples may be located within the catalyst
     container at the approximate mid-point of the exhaust stream and
     approximately one inch from the substrate.

5.    Carryover may not be approved for any components or systems that were
     used in families certified without completing the 50,000-mile
     certification provout  under the small volume provisions of  40 CFR
     86.082-24(e).   Manufacturers must continue to submit requests to EPA for
     carryover involving systems or components that have not completed the
     50,000 mile certification proveout.  Requests for carryover may also be
     submitted to EPA if the 50,000-mile certification proveout  has been
     successfully completed but a certificate was never obtained.

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                                  Attachment

          CARRYOVER CRITERIA  FLOW CHART FOR 40 CFR PART 86 VEHICLES
NO
7


NO CERT.
UR F.E.
c/o
(1)  c/o - carryover

(2)  EUV - emission-data
           vehicles

(3)  FE - fuel economy

(4)  FEDV - fuel economy
            data vehicles
NOTE 1:
USE 1983 FE DATA AND
1982 CERT. DATA FOR C/O.
USE 1902 FE DATA PRO-
VIDED 1983 FEDV DATA
CONFIRMS 1982 DATA IS
REASONABLE.

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                         UPDATE
Attached are revised  pages  to  replace the  endnotes of  Advisory
Circular No.  17F.   Please discard pages  16  and 17  of the
endnotes issued  November  16, 1982 and insert the  revised  pages
dated  January   21,  1988.   Explanation  of  the  revisions   is
provided  in  manufacturer   guidance   letter   CD-88-02,   dated
January 21,  1988.

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                U.S. Environmental  OANR/MS            A/C NO.   I?F
                Protection Agency                           PAGE_IL_ OF.H
XI.   General  Criteria for Carryover of Fuel Economy  Data  from Vehicles Other
      Than Those  for Which Certification Carryover is Requested

      A.  A request for carryover of fuel economy data from vehicles other
than those for which certification carryover is requested  must be submitted
with an FEDV package indicating that the data are from a prior model year.

      B.  Vehicles other than those for which certification carryover is
requested must satisfy the criteria set forth in Section V of this A/C to be
considered for fuel economy carryover.

      C.  Since the vehicles which generated these data have previously
satisfied the  vehicle acceptability and data reasonableness criteria, the data
need only satisfy the representativeness criteria (paragraph X.D of this A/C).

      D.  Data which satisfy all of the criteria will be included in the fuel
economy data base in accordance with the provisions of 40  CFR 600.008-77(b).

      E.  Any  vehicle which does not satisfy the certification carryover
criteria and/or data which do not satisfy the representativeness criteria will
cause the carryover request to be denied.
                                         arson
                     Director, Office of Mobile  Sources
Attachment

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                    U.S. Environmental  OAR/OMS            A/C NO..
                    Protection Agency
                     ENDNOTES TO ADVISORY CIRCULAR NO.  17F
1.  "Qualified  to  be'  grouped  in  the  same  engine  family" means  that  the
    current  year  vehicle  and  the  vehicle  which  generated   the   proposed
    carryover'  data  must  be identical  in  all  the  aspects  listed  in  A/C
    No. 20B, Sections D,  E,  F  (four-stroke,  two-stroke,  or  rotary  engines
    respectively).

2.  "Qualified to be grouped in the same  evaporative emission  family",  means
    that  the  current  year  vehicle  and  the  vehicle  which  generated  the
    proposed carryover data  must  be identical in'all the  aspects-listed  in
    A/C No. 59, Section D.

3.  The same basic evaporative  emission control  system  as specified in  A/C
    No. 59, Section  E.

4.  It  is  the  manufacturer's responsibility to  assure  that  an increase  in
    catalyst temperature will not result in  increased thermal  degradation  of
    the catalyst.  If  the manufacturer'has any reason to-suspect1 that  thermal
    degradation of  the catalyst will  increase significantly,   carryover - may
    not be  approved.  EPA believes that thermal  degradation of  the  catalyst
    is not likely to  increase if'catalyst  temperatures do  not  increase.   EPA
    intends to look  more closely at those cases  where  catalyst temperatures
    increase significantly.   Criteria are of-fered below  as a guideline  to
    determine  if   catalyst  temperatures are significantly affected.   These
    criteria allow small  increases  in  time  and  temperature  to account  for
    measurement   variability.   A   manufacturer  may  determine  that  other
    criteria are  more appropriate  for establishing  the  acceptability  of
    carryover  for its  designs.  The manufacturer should  document the  basis
    for its determination that  thermal  degradation of the  catalyst will  not
    increase significantly.   If a  manufacturer believes  that  the  following
    guideline is not appropriate for a particular  situation and  can  document
    that thermal  degradation of the catalyst will not  increase even though
    these criteria are not met, durability  carryover may  still  be  approved.
    However, when the  following criteria are not met,  the manufacturer should
    notify EPA in writing  at the  time the carryover decision  is made.   This
    will  allow  most  timely  EPA  audit  of  the  manufacturer's   carryover
    decision.    The  amount  of  time  spent  in  the  following  temperature
    intervals  is  not  increased  by  more  than  3 percent  or  60  seconds,
    whichever  is  greater, during  the  mileage  accumulation cycle  (approxi-
    mately 2 hour cycle)  unless there is a corresponding decrease  in  time at
    a higher temperature interval.   The temperature intervals higher  tempera-
    ture interval.   The  temperature  intervals are 601°C  to 650°C, 651°C  to
    700°C,  701°C  to  750°C,  and 751°C to 800°C  (other  intervals within  this
                                                            Revised:   1-21-88

-------
                  U.S. Environmental  OAR/OMS            A/C NO.    17F
                  Protection Agency                           PAGE_1Z_ OFJL
    range may  be  appropriate,  the  60  second  tolerance  applies  to  a 50°C
    interval).   If maximum temperatures  are above 800°C, the maximum tempera-
    ture is not increased  by more  than  2 percent  and amount  of  time above
    800°C is not increased by more  than  2 percent or 30 seconds, whichever is
    greater.  If the catalyst uses  AlzOj  for support but does not contain
    Hi,  only   increases  in  time  at  temperatures  above 700°C  need  to  be
    considered.  For oxidation  catalysts which  use  AlzOs  for  support  but
    do not  use Ni  and  do not  use Rh,  only increases  in time at temperatures
    above 750°C need to be considered.

    Whenever possible,  the  impact of  a  change  on  catalyst temperatures
    should  be   evaluated  on  a  single  vehicle,  preferably  the  original
    durability-data vehicle.  If  the original  durability-data  vehicle  is not
    available,  the  highest selling configuration  from  either of  the model
    years is preferred.   If it  is not practical to evaluate the  change on a
    single  vehicle,  other vehicle  differences which could  affect catalyst
    temperatures  should  be minimized.   Again, configurations representing
    highest sales  from  each model year should be used  if practical.

    Thermocouples   should  be  located  to  provide  accurate  measurement  of
    maximum temperatures.  Each manufacturer should obtain a  description  of
    such location  from  his catalyst supplier  and  retain  this  with the rest
    of the documentation.  If this is not  possible,  for monolith catalysts.
    thermocouples   may   be located  within  the  catalyst substrate   at  the
    approximate radial  center of the exhaust  stream  and approximately  one
    inch downstream  from the  front face of the  substrate.   If the catalyst
    is composed of  multiple containers or multiple  substrate  biscuits  in the
    same  container,  more  than  one  thermocouple  is  required.   Locate  one
    thermocouple  within each substrate biscuit as  described  above.   Thermo-
    couples should not be  located  in  the exhaust  pipe,  in free exhaust air,
    or directly in  the  delivery path of  secondary air  injection systems.

5.   Carryover may not be  approved  for  any  components or systems  that were
    used in families certified without  completing  the 50,000-mile certifica-
    tion proveout under the small-volume provisions of  40 CFR 86.082-24(e).
    Manufacturers  must  continue  to  submit  requests  to  EPA  for  carryover
    involving systems or components that have  not  completed  the  50,000-mile
    certification  proveout.  Requests  for carryover may also be submitted to
    EPA  if  the  50,000-mile  certification  proveout  has  been successfully
    completed but a  certificate was never obtained.
                                                           Revised:  1-21-88

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                                   Attachment

           CARRYOVER CRITERIA FLOW CHART FOR 40 CFR PART 86 VEHICLES
NO
^


NO CEKT.
UR F.E.
c/o
       ARE FE DATA
     REPRESENTATIVE
(1)  c/o - carryover

(2)  EUV - emission-data
           vehicles

(3)  FE - fuel economy

(4)  FEDV - fuel economy
            data vehicles
MOTE 1.
USE 1983 FE DATA AND
1982 CERT. DATA FOR c/o.
USE 1982 FE DATA PRO-
VIDED 1983 FEDV DATA
CONFIRMS 1982 DATA IS
REASONABLE.
SEE
MOTE
1
                                                          MEETS    "X.NO
                                                     EMISSION STAND-
                                                          ARDS

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