UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

National Vehicle and Fuel Emissions Laboratory

2000 Traverwood Drive

Ann Arbor, Michigan 48105-2498

March 27, 2012

MEMORANDUM

SUBJECT: Discussion with Pratt & Whitney USA Regarding the Leadtime Associated the 

Proposed Aircraft Engine Tier 6 NOx Production Cutoff—December 19, 2011

FROM: Richard S. Wilcox, Environmental Scientist

Assessment and Standards Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

TO: The Air and Radiation Docket

Docket No. EPA-HQ-OAR-2010-0687

This documents a discussion we had on December 19, 2011 with representatives of Pratt 

& Whitney USA (P&W) to clarify a public comment they submitted on our Notice of Proposed 

Rulemaking for new aircraft engine NOx emission standards and other requirements (July 27, 

2011, 76 FR 45012).1Specifically, P&W expressed a concern that there may be inadequate 

leadtime for the EPA and the Federal Aviation Authority (FAA) to establish and review 

exemption requests by the January 1, 2013 date of the proposed Tier 6 production cutoff for 

engines that were originally certified to the Tier 4 standards. They suggested that a small number 

of automatic low-volume exemptions be included in the final rule to prevent any potential 

interruption in engine production.

Attending the call for EPA were Mike Samulski, Glenn Passavant, John Mueller, and 

myself. Attending for P&W were Alan Epstein, Domingo Sepulveda, Larry Jones, Matthew 

Stoner, Maher Awkal, and Roger Martella. P&W indicated a continuing concern regarding the 

availability of a limited number of exemptions prior to the proposed production cutoff date of 

January 1, 2013. 

 

1 U.S. EPA, “Summary and Analysis of Comments: Control of Air Pollution from Aircraft and Aircraft Engines,” 

Office of Transportation and Air Quality, EPA-420-R-12-011. A copy of this document is in docket number EPAHQ-OAR-2010-0687. 
 

Specifically, P&W has two engine models that are both at the end of their production 

lives, i.e., 4 engines of one model and two engines of another model, that were sold years ago 

with contracted delivery dates that would be adversely affected by the production cutoff as 

proposed.

They noted that the first model with four engines already had been modified to comply 

with the Tier 6 standards. However, they also noted that testing and certification by the FAA 

would take several months, well beyond the January 1, 2013 cutoff date. These engines have 

contract delivery dates beginning in January 2013. The other model consisting of two engines 

was certificated to the Tier 4 standards and P&W indicated that it was not feasible to modify that

model to be Tier 6 compliant. These engines have contract delivery dates in the May 2013 

timeframe. Pratt and Whitney claimed that any delay in shipping any of these engines would 

represent a significant adverse economic effect for the company, the aircraft manufacturer, and 

the airline customers. All of the engines apparently would be delivered to foreign airlines.

We discussed P&W’s idea regarding automatic low-production exemptions for these six

engines. They expressed a desire that at least the four engines ,which were expected to comply 

with the Tier 6 standards, not be labeled as “Exempt New” because that could devalue the 

engines in the secondary market. We acknowledged that granting exemptions using the 

traditional approach based on a petition for relief from the manufacturer was questionable. As an 

alternative to P&W’s proposed solution, we also discussed the possibility and ramifications of 

delaying the implementation date of the requirement for several months.