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type...."   We chose not to propose adopting this language on the nominal number of engines based on a single type certificate.  Our reasons for this deviation were detailed in the.  The interested reader is referred to the proposed rule for more detail.    (See 76 FR 45012. July 27. 2011.)  We also want to emphasize that the exemption provisions as proposed and promulgated in this notice are not necessarily limited to the Tier 6 NOx production cut-off, but could in fact be applied to future aircraft engine emission standards if a similar production cut-off was adopted.  Therefore, we believe our approach is preferable because it more clearly leaves the number of exemptions that might be granted open, not limited to either more or less than 75 per engine type, and subject to the justification supplied by the engine manufacturer, both for the Tier 6 production cut-off and the future.
We received several comments focusing primarily on the number of exemptions and the underlying process that is embodied in the ETM and our proposal.  General Electric Aviation (GE) maintained that harmonization with the international community is not only required by the Chicago Convention, but also provides streamlined processes and procedures within the regulated industry.  They contended that any purported benefits to EPA's unique exemption scheme were outweighed by setting up a conflict with the remainder of the world.  They also suggested that if EPA wants a different approach for evaluating exemptions, it would be more appropriate to work inside the ICAO/CAEP process toward that end.

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This section specifies provisions related to exempting/excepting engines from some or all of the standards and requirements of this part 87. Exempted/excepted engines must conform to regulatory conditions specified for an exemption in this section and other applicable regulations. Exempted/excepted engines are deemed to be "subject to" the standards of this part even though they are not required to comply with the otherwise applicable requirements. Engines exempted/excepted with respect to certain standards must comply with other standards.  Exemption requests under paragraph (a) of this section must be approved by the FAA, with the written concurrence of EPA, to be effective.  Exemption requests under paragraph (b) of this section must be approved only by the FAA to be effective.  Exceptions do not require a case-by-case FAA approval.  
(a) Engines installed in new aircraft.   Type certificate holders may request an exemption to produce a limited number of newly manufactured engines through December 31, 2016, to be installed in new aircraft as specified in this paragraph (a). This exemption is limited to NOx emissions from engines that are covered by a valid type certificate issued by FAA.    
   (1) Submit your request for an exemption to the FAA before producing the engines to be exempted, who will provide a copy to the Designated EPA Program Officer.  Exemption by an authority outside the United States does not satisfy this requirement.  Unless EPA and FAA allow otherwise, all requests must include the following:

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the 2006 24-hour PM2.5 standard of 35 ug/m[3] without additional controls.[,]  These numbers do not account for those areas that are close to (e.g., within 10 percent of) the standards.  These areas, although not violating the standards, would also benefit from any reductions in NOX ensuring long-term maintenance of the NAAQS.
In summary, the aircraft NOx reductions resulting from these new aircraft engine emission standards will be useful to states in attaining or maintaining the ozone, PM2.5 , and NO2 NAAQS standards.
III.  Details of the Final Rule
The following is a description of the regulations being adopted in this final rule, with any changes from the proposal also noted.  The descriptions also include our response to the most significant comments received on the proposal.  A full summary of the comments and our responses are contained in the response to comments document for the rule that is available in the public docket for this action.
   


