EPA is proposing to adopt emission standards and related provisions for aircraft gas turbine engines with rated thrusts greater than 26.7 kilonewtons. These engines are used primarily on commercial passenger and freight aircraft. The proposed requirements were either previously adopted by the International Civil Aviation Organization (ICAO), or agreed on at ICAO’s Committee on Aviation Environmental Protection (CAEP) in 2010. Included in the proposal are two new tiers of more stringent emission standards for oxides of nitrogen (NO_x). These are referred to as Tier 6 (or CAEP/6) standards and Tier 8 (or CAEP/8) standards. The proposed standards would become effective for newly-manufactured aircraft engines beginning in 2013.

• Proposed Rule (PDF)(42 pp, 650 K, published July 27, 2011, About PDF)