The Environmental Protection Agency (EPA) is proposing to amend U.S. regulations governing exhaust emissions from new commercial aircraft gas turbine engines on regional jets, single-aisle aircraft, twin-aisle aircraft, and larger aircraft such as 747s.

EPA, under the Clean Air Act (CAA), is proposing new emission standards for oxides of nitrogen (NO_x) for newly certified commercial aircraft gas turbine engines with rated thrust greater than 26.7 kilonewtons (kN). The action would adopt standards equivalent to the latest NO_x standards of the United Nations International Civil Aviation Organization (ICAO), and would bring the U.S. emission standards into alignment with internationally adopted standards.

In addition, the proposed rule would amend the test procedures for gaseous exhaust emissions to correspond to recent amendments to the ICAO test procedures for these emissions.

Beginning in 2004, the proposed NO_x standards would apply to newly certified gas turbine engines -- those engines designed and certified after the effective date of the proposed regulations (the date of manufacture of the first individual production model means the date of type certification).

Since the proposed NO_x standards would apply to only newly certified gas turbine engines, newly manufactured engines (those engines built after the effective date of the proposed regulations) would not have to meet these standards. Also, all engines currently being built would not have to comply with the NO_x emission standards that EPA is proposing.

The changes to the emission test procedures are the same as those recommended by ICAO and are widely used by the aircraft engine industry. EPA said the changes would establish consistency between U.S. and international standards, requirements and test procedures.

Comments on the proposal are due by Dec. 15.

>>Contact: John Millett, EPA, 202-564-7842; Web: http://www.epa.gov/otaq/aviation.htm.<<