United States Air and Radiation EPA420-F-97-010
Environmental Protection April 1997
Agency
Office of Mobile Sources
&EPA Environmental
Fact Sheet
Adopted Aircraft Engine
Emission Standards
The Environmental Protection Agency (EPA) is promulgating new emission
standards for oxides of nitrogen (NOx) and carbon monoxide (CO) for
commercial aircraft engines. This rule will adopt the current voluntary NOx
and CO emissions standards of the United Nations International Civil
Aviation Organization (ICAO), bringing the United States aircraft standards
into alignment with the international standards.
Emissions From Aircraft Engines
Aircraft engines contribute about 2 percent of the total U.S. mobile source
NOx and CO emissions. However, in some U.S. airport areas, aircraft can
contribute up to 4 percent of mobile source NOx emissions. Commercial
aircraft emissions are a fast growing segment of the transportation emissions
inventory. In the Los Angeles area for example, commercial aircraft NOx
emissions are expected to double by 2010. This growth is occurring at a time
when other significant mobile and stationary sources are drastically reducing
emissions, thereby accentuating the growth in aircraft emissions.
Health and Environmental Concerns
NOx is harmful to human health and the environment. Nitrogen dioxide, a
form of NOx, can reduce pulmonary function and increase airway irritation
in healthy people as well as individuals with pre-existing pulmonary condi-
tions. The risk of respiratory illness appears to increase in children exposed
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to nitrogen dioxide. NOx contributes to acid rain, which affects both terres-
trial and aquatic ecosystems, including acidification of waters, reductions in
fish populations, damage to forests and wildlife, soil degradation, and
damage to materials, monuments, and buildings. NOx is also a precursor to
ozone, which affects both biological tissues and man-made materials.
Ozone affects human pulmonary and respiratory health and causes damage
to forests and vegetation. NOx emissions could also form secondary par-
ticulate matter, which causes detrimental health and welfare effects.
CO also has significant human health effects. CO enters the blood stream
through the lungs and reduces the delivery of oxygen to the body's organs
and tissues. Persons with heart disease are especially sensitive to CO and
may experience chest pain when breathing CO. Infants, elderly persons,
and individuals with respiratory diseases are also particularly sensitive. CO
can affect healthy individuals, impairing exercise capacity, visual percep-
tion, manual dexterity, learning ability and the ability to perform complex
tasks.
To protect public health and the environment, EPA has established National
Ambient Air Quality Standards (NAAQS) for air pollutants, including
nitrogen dioxide, ozone, CO, and PM. Because aircraft emissions contrib-
ute to increases in these air pollutants, the ICAO aircraft standards adopted
in this rule will help states achieve and/or maintain compliance with
NAAQS.
History of EPA's Regulation of Aircraft Engine
Emissions
Prior to this rule, EPA regulations on aircraft were limited to smoke and fuel
venting emissions standards for all commercial jet aircraft classes. This
includes: turboprop engines (TP); turbofan and turbojet engines (TF);
turbine engines of the JT3D model family (T3); turbine engines of the JT8D
model family (T8); and turbine engines for aircraft designed to operate at
supersonic flight speeds (TSS). EPA also had HC emission standards for
newly manufactured aircraft gas turbine engines (TF, T3, and T8) with a
thrust greater than 26.7 kN. Separate HC emission standards exist for gas
turbine engines employed in supersonic aircraft, and the smoke standards
vary for the several different classes of engines. EPA regulations for smoke
and HC emissions have been in effect since 1984.
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EPA's Participation in ICAO
EPA has worked with the Federal Aviation Administration (FAA) of the
Department of Transportation and ICAO in the development of international
aircraft emission standards. FAA is responsible for enforcing the aircraft
emissions standards established by EPA. ICAO was established by the
United Nations to ensure equality and consistency among international air
transport services. One of ICAO's objectives is to lead international bodies
in the development of standards and procedures for aircraft engines. The
United States is one of more than 150 participating member States of ICAO.
Under the basic ICAO treaty established in 1944, the participating nations
have an obligation to adopt, to the extent possible, the ICAO standards.
However, ICAO standards are voluntary. EPA has been supportive of the
ICAO development of aircraft standards and this rule formalizes EPA's
adoption of ICAO standards.
Main Components of the Rule
This rule will codify into United States law the current voluntary NOx (a
two-staged NOx standard) and CO emission standards of ICAO, and
thereby bring the United States emission standards into alignment with the
internationally adopted standards. The ICAO CO and first-stage NOx
standards have been in effect since 1986. In addition, EPA is amending the
test procedures for gaseous exhaust emissions and smoke exhaust emissions
to correspond to recent ICAO amendments. EPA is also adopting ICAO's
requirement that these standards also apply to applications that otherwise
would have been fulfilled by turbojet and turbofan engines (e.g. propfan,
unducted fan, and advanced ducted fan). United States certification test fuel
specifications are also being amended to make them consistent with ICAO's
test fuel specifications. The adopted emission standards and test procedures
apply to commercial aircraft engines with rated thrust greater than 26.7
kilonewtons (kN) that are either newly certified or newly manufactured after
the effective date of these regulations. No general aviation or military
engines are covered by this rule. The adopted emission standards are
described below.
CO Standard
The CO standard applies to newly manufactured aircraft gas turbine engines
(turbofan and turbojet engines).
CO =118 grams/kilonewton (g/kN)(rated output)
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NOx Standards
The NOx standards apply to newly certified and newly manufactured
aircraft gas turbine engines (turbofan and turbojet engines).
• For engines of a type or model of which that date of manufacture of the
first individual production model was on or before December 31, 1995
and for which the date of manufacture of the individual engine was on or
before December 31, 1999:
NOx = (40 + 2(rated pressure ratio))g/kN(rated output);
• For engines of a type or model of which the date of manufacture of the
first individual production model was after December 31, 1995 or for
which the date of manufacture of the individual engine was after Decem-
ber 31, 1999:
NOx = (32 + 1.6(rated pressure ratio))g/kN(rated output).
The first NOx emission standard presented above matches the ICAO stan-
dard that became effective in 1986. The second NOx emission standard
above matches the ICAO 1993 amendments which will result in a 20 percent
reduction and will become effective in the year 1996 for newly certified
engines and in the year 2000 for newly manufactured engines. There is a
four year period between when newly certified engines must meet the
standards and when all newly manufactured engines must meet the standards
to provide lead time for the production of 100 percent compliant products.
Benefits of Adopting ICAO Standards
This rule will establish consistency between U.S. and international stan-
dards, requirements, and test procedures. Since aircraft engines are interna-
tional commodities, there is a commercial benefit to consistency between
U.S. and international emission standards and control program requirements.
It would be easier for manufacturers to certify products for international
markets since the U.S. can certify engines for ICAO compliance. Emission
certification tests meeting U.S. requirements will also be applicable to all
ICAO requirements. In addition to the economic benefit, this rule ensures
that domestic commercial aircraft will meet the current ICAO standards, and
thus, the public can be assured they are receiving the air quality benefits of
the international standards.
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All engines covered by the new federal standards already meet ICAO
standards or will meet them by the standards' effective dates. Manufactur-
ers have already been developing improved technology in response to the
ICAO standards. Therefore, there are no additional costs to be incurred by
the aircraft industry as a result of this rule. In addition, the test data neces-
sary to determine compliance are already collected by manufacturers during
current engine certification tests. Thus, the regulations will impose no
additional burden on manufacturers.
For More Information
Information on aircraft emission standards is available electronically via the
EPA Internet server or via dial-up modem on the Technology Transfer
Network (TTN), an electronic bulletin board system (BBS).
World Wide Web: http://www.epa.gov/OMSWWW
TTN BBS: 919-541-5742 (1200-14400 bps, no parity, 8 data bits,
1 stop bit); voice helpline: 919-541-5384.
For further information, please write to:
U.S. Environmental Protection Agency
Engine Programs and Compliance Division
2565 Plymouth Road
Ann Arbor, Michigan 48105
or call: (313)668-4333.
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