The US Environmental Protection Agency (EPA) is proposing to adopt new air pollution standards for engines with rated thrusts greater than 26.7 kilonewtons (kN) used primarily in large commercial aircraft, including 737s, 747s, and 767s. The proposal would reduce ground-level NOx emissions by an estimated 100,000 tons nationwide by 2030.
The standards were previously agreed to by the United Nation’s International Civil Aviation Organization (ICAO). Due to the global nature of air travel, EPA works with international agencies to ensure significant and cost effective emissions reductions. If adopted in the United States, the standards would be phased in over the next two years, applying to all new engines in 2013.
Specifically, EPA is proposing two new tiers of more stringent emission standards for NOx: the Tier 6 (or CAEP/6) standards and the Tier 8 (or CAEP/8) standards.
The proposed standards would apply differently depending on the date the engine model received its original airworthiness certificate as follows:
Engine models that were originally certificated prior to the effective date of the proposed rule may continue production without meeting the proposed Tier 6 standards through 31 December 2012. After that date, these engines must comply with the proposed Tier 6 standards (this date is generally referred to as the Tier 6 production cutoff). This delay in complying with the proposed Tier 6 standards for previously certificated engine models is intended to allow for an orderly transition to the proposed Tier 6 standards.
Engine models that were originally certificated between the effective date of the proposed rule and 31 December 2013 must comply with the proposed Tier 6 standards.
Engine models that were originally certificated beginning on or after 1 January 2014 must comply with the proposed Tier 8 standards. EPA anticipates establishing a future production cutoff to require all engine models that were originally certificated before the above date to comply with the proposed Tier 8 standards.
EPA is also proposing several additional changes that would affect all aircraft gas turbine engines that are subject to current emission requirements. First, EPA is proposing to clarify when a design variation of a previously certified engine model causes the emission characteristics of the new version to become different enough from its parent engine that it must conform to the most current emissions standards.
Second, EPA is proposing amendments to the emission measurement procedures. These revisions are primarily intended to reflect current certification practices.
Finally, EPA is proposing to require all gas turbine and turboprop engine manufacturers to report to EPA, emission data and other information necessary for the purpose of conducting emission analyses and developing appropriate public policy for the aviation sector.
Comments will be accepted for 60 days after the date that the proposal is published in the Federal Register.