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Regulatory

Announcement

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA420-F-03-029

September 2003

Office of Transportation and Air Quality

Proposed Aircraft Engine

Emission Standards

The U.S. Environmental Protection Agency (EPA) is proposing to

amend the existing emission standards for oxides of nitrogen (NOx) for

new commercial aircraft engines. These new standards are equivalent

to the latest NOx emission standards of the United Nations

International Civil Aviation Organization (ICAO), and thereby would

bring the United States aircraft standards into alignment with the

international standards.

These standards would go into effect in 2004 and would apply to new

aircraft engines utilized on commercial aircraft that include small

regional jets, single-aisle aircraft, twin-aisle aircraft, and 747s and

larger aircraft. General aviation and military aircraft can use commercial

aircraft engines subject to this proposal (e.g., small regional jet engines

are also utilized in executive general aviation aircraft and larger

commercial aircraft engines may also be used in military transport

aircraft).

Emissions From Aircraft Engines

Aircraft engines contribute about 1 percent of the total U.S. mobile

source NOx emissions. However, in some U.S. airport areas, aircraft

currently can contribute up to 4 percent of mobile source NOx emissions. Commercial aircraft emissions are a growing segment of the

transportation emissions inventory. This growth is occurring at a time

when other significant mobile and stationary sources are drastically

reducing emissions, thereby accentuating the growth in aircraft emis-
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sions. In the Atlanta area for example, NOx emissions from commercial

aircraft are expected to more than double by 2010 and contribute as

much as 10 percent of mobile source NOx emissions. (These growth

projections do not include the impact of the September 11 terrorists’

attacks and the subsequent economic downturn. However, the Federal

Aviation Administration (FAA) expects the demand for air travel to

recover, and then continue a long-term trend of annual growth in the

United States. Recently, FAA reported that flights of commercial air

carriers will increase by 18 percent from 2002 to 2010 and 45 percent

from 2002 to 2020.)

Health and Environmental Concerns

The emissions from aircraft engines that are being directly controlled by

the standards proposed in this rulemaking are NOx emissions. NOx

emissions are a precursor to the formation of ground-level ozone, also

called smog. Ozone affects human pulmonary and respiratory health.

Also, NOx reacts in the atmosphere to form secondary particulate matter

(PM2.5), which causes detrimental health effects. In addition, NOx,

ozone, and PM adversely affect the environment in various ways including visibility impairment, crop damage, and acid rain.

To protect public health and the environment, EPA has established

National Ambient Air Quality Standards (NAAQS) for several air

pollutants, which includes ozone and PM. Recent air quality data show

that about 111 million people live in areas that violate air quality standards for ground-level ozone. About 70 million people live in areas that

violate air quality standards for PM. Because aircraft emissions contribute to increases in these air pollutants, the proposed aircraft engine

standards would help states achieve and/or maintain compliance with the

NAAQS.

History of EPA’s Regulation of Aircraft Engine

Emissions

The aircraft emission standards for gas turbine (jet) engine have been in

place for about thirty years. Emission standards apply to essentially all

commercial aircraft, comprising scheduled and freight airlines. Two

classes of aircraft, military and general aviation, are presently not covered. Emission controls on engine smoke and prohibitions on fuel

venting were instituted in 1974 and have been revised several times
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since then. EPA standards for unburned hydrocarbon emissions (HCs),

which align with ICAO HC standards, have been in effect since 1984

(including separate HC standards for gas turbine engines employed in

supersonic aircraft). Also, in May 1997, EPA adopted standards equivalent to the existing ICAO NOx and carbon monoxide (CO) standards.

EPA’s Participation in ICAO

EPA has worked with the FAA 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 safety, 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 188 participating member

States of ICAO. Under the basic ICAO treaty established in 1944, a

participating nation which elects not to adopt the ICAO standards must

provide a written explanation to ICAO describing why a given standard

is impractical to comply with or not in their national interest. In this

rulemaking, EPA proposes to adopt standards equivalent to the latest

ICAO standards.

Main Components of the Rule

This rulemaking proposes to codify into United States law requirements

equivalent to ICAO’s February 1999 NOx emission standards and March

1997 test procedure amendments, thereby bringing the United States

emission standards and test procedures into alignment with the internationally adopted standards and test procedures. The proposed NOx

emission standards would become effective in the year 2004, and these

standards generally represent about a 16 percent reduction (or increase in

stringency) from the existing NOx standards. These proposed emission

standards would apply to commercial aircraft engines with rated thrust

greater than 26.7 kilonewtons (kN) that are newly certified (and designed) after the effective date of the regulations. General aviation and

military aircraft can use commercial engines subject to this proposal, and

thus, emission benefits would be realized from these type of aircraft.

Benefits of Adopting ICAO Standards

This proposed rule would establish consistency between U.S. and international emission standards and test procedures. Since aircraft engines
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are international 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 proposed rule would ensure that domestic

commercial aircraft will meet the current ICAO standards, and thus, the

public would be assured they are receiving the air quality benefits of the

international standards.

Nearly all (94 percent) already certified or in-production engine models

currently meet or perform better than the standards we are proposing to

adopt in this proposed rulemaking. In addition, manufacturers have

already been developing improved technology in response to the ICAO

standards. Therefore, there are no additional costs that would be incurred

by the aircraft industry as a result of this proposed rule. In addition, the

test procedures necessary to determine compliance are already being

adhered to by manufacturers during current engine certification tests.

Thus, the regulations will impose no additional burden on manufacturers.

Public Participation Opportunities

The proposal and related documents are available on the Office of

Transportation and Air Quality (OTAQ) Web site at: www.epa.gov/otaq/

aviation.htm. We welcome your comments on this proposal. You can

comment via email by sending a message to aircraft@epa.gov. For

instructions on additional ways to send comments, please see the Federal

Register notice. It is available on the Web site above or by calling the

EPA Air Docket at (202) 566-1742; please refer to Docket No. OAR2002-0030. You may submit written comments until December 15, 2003.

We will also hold a public hearing in Washington, DC, on November 13,

2003, at:

U.S. Environmental Protection Agency

EPA East Building

Room Number 1153

1201 Constitution Avenue, N.W.

Washington, DC 20004

Telephone: (202) 564-1682
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Detailed information about the hearings will be published in the Federal

Register and at www.epa.gov/otaq/aviation.htm.

For More Information

You can access documents on aircraft emissions electronically on the

OTAQ Web site given above, or by contacting the OTAQ library at:

U.S. Environmental Protection Agency

Office of Transportation and Air Quality Library

2000 Traverwood Drive

Ann Arbor, MI 48105

(734) 214-4311 & 214-4434

E-mail: Group_AALibrary@epa.gov