EPA Adopts NOx Emission Standards
for Aircraft Gas Turbine Engines
The U.S. Environmental Protection Agency (EPA) is publishing a
final rulemaking to adopt the NOx emission standards approved
by the United Nation's International Civil Aviation Organization
(ICAO).
Overview
EPA is adopting emission standards and related provisions for aircraft gas turbine
engines with rated thrusts greater than 26.7 kilonewtons. These engines are used pri-
marily on commercial passenger and freight aircraft. The final rule contains standards
and related provisions that were previously adopted by ICAO. Specifically, EPA is
adopting two new tiers of more stringent emission standards for oxides of nitrogen
(NOx). These are referred to as the Tier 6 (or CAEP/6) standards and the Tier 8 (or
CAEP/8) standards.
The standards will apply differently depending on the date the engine model received
its original type certificate as follows,
• Engine models that were originally certificated prior to the effective date
of the rule may continue production without meeting the Tier 6 standards
through December 31, 2012. After that date, these engines must comply with
the new Tier 6 standards (this date is generally referred to as the Tier 6 pro-
duction cutoff). This delay in complying with the Tier 6 standards for previ-
ously certificated engine models is intended to allow for an orderly transition
to the Tier 6 standards,
• Engine models that were originally certificated between the effective date of
the rule and December 31, 2013 must comply with the Tier 6 standards,
• Engine models that were originally certificated beginning on or after January
1, 2014 must comply with the 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 Tier 8 standards. We
will consider this in a future action after first pursuing it within ICAO,
SEPA
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA-420-F-12-027
June 2012
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EPA is also adopting several additional changes that would affect all aircraft gas turbine engines
that are subject to current emission requirements. First, EPA is clarifying when a design varia-
tion 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 amending the emission measurement procedures. These
revisions are primarily intended to reflect current certification practices. Finally, EPA is requir-
ing all gas turbine and turboprop engine manufacturers that are subject to exhaust emission
standards 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.
These regulatory requirements, except a portion of the engine manufacturer reports, have
already been adopted, are consistent with, or are actively under consideration by the ICAO,
The requirements are consistent with the United Nations Convention on International Civil
Aviation,
For More Information
You can access the rule and related documents on EPA's Office of Transportation and Air Quality
(OTAQ) Web site at:
www.epa.gov/otaq/aviation.htm
For more information on this final rule, please contact the Assessment and Standards Division at:
U.S. Environmental Protection Agency
Assessment and Standards Division
Office of Transportation and Air Quality
2000 Traverwood Drive
Ann Arbor, MI48105
Voice-mail: (734) 214-4636
E-mail: asdinfo@epa.gov
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