Business Aviation Law Blog

Late last month, EPA adopted new nitrogen oxide (“NOx”) emissions standards for aircraft engines that align with international requirements previously promulgated by the International Civil Aviation Organization (“ICAO”). According to the Final Rule [77 Fed. Reg. 36342], the regulations reduce NOx emissions from taxiing, take off, landing, idling, and flight for certain gas turbofan engines used by commercial and non-commercial civilian aircraft with maximum rated thrusts greater than 26.7 kilonewtons (“kN”). Although engines with this rating are primarily used in the commercial sector, the rule makes clear that the standards also apply to non-commercial civilian aircraft engines that are required to obtain airworthiness certificates.

Prior to this rule, gaseous emissions regulations were limited to commercial civilian aircraft engines. The inclusion of non-commercial aircraft engines, according to the Final Rule, was because ICAO’s standards and recommendations already apply to both sectors. This rule, therefore, brings EPA’s regulations into full conformance. Further, manufacturers already certify the engines to the international standards, thus “this provision simply incorporates the status quo.” Finally, the inclusion was necessary because of the physical and operational similarities between the aircraft engines used in the two sectors.

To facilitate an orderly transition, EPA adopted two tiers of emissions standards: (1) Tier 6 (or CAEP/6) standards and (2) stricter Tier 8 (or CAEP/8) standards. Implementation of the Tier 6 standards will result in a 12 percent reduction in emissions levels below the current Tier 4 standards. The Tier 8 standards will result in a 15 percent reduction in emissions levels below the Tier 6 standards. The applicability of the tiers depends on the manufacturing date and certification date of the engine model.   

• Tier 6 Standards: If the engine model is manufactured and certified before July 18, 2012, the engine model would not be required to comply with the Tier 6 standards until December 31, 2012. Any engine model certified on or after July 18, 2012, must comply by December 31, 2013.

• Tier 8 Standards: Any engine model certified on or after January 1, 2014, must comply with the Tier 8 standards. 

The Final Rule also includes several changes that affect all aircraft gas turbine engines subject to current emission requirements. The Final Rule:

• clarifies when a design variation of a new engine causes the latest version to become different enough from its previously certified parent engine that it must conform to the most current emissions standards;

• amends the emission measurement procedures to reflect current certification practices; and

• requires covered gas turbine and turboprop engine manufacturers to report emissions data to EPA to conduct analysis and define appropriate public policy.

According to EPA, this rule “is not an economically significant regulatory action” and “will impose no real additional burden on engine manufacturers” because aircraft turbofan engines are already designed and built to ICAO standards in order to be sold and operated worldwide. Overall, only ten engine manufacturers will be affected by this rule. EPA estimates that the total annual burden of compliance is approximately ten hours and $365 per manufacturer. 

This is not the first time that EPA has revised its standards for aviation emissions to conform to ICAO guidelines, nor will it be the last. As covered extensively in several previous posts, if ICAO develops universal and comprehensive standards for aviation greenhouse gas emissions, EPA may soon revise its regulations to follow suit.  

More information on the new NOx standards can be found on EPA’s website.

Special thanks to Sullivan & Worcester’s Noah Tomares, Environmental and Marketing Intern, for assistance in preparing this post.