Summary of Interagency Working Comments on Draft Language under 

EO12866 Interagency Review. Subject to Further Policy Review.

1) Please provide a detailed outline of the provisions of this rulemaking that deviate from 

the recommendations of ICAO and provide a detailed justification and policy rationale 

for why EPA is proposing to deviate from these recommended standards. The United 

States has an obligation under the Article 2.4 TBT Agreement to follow international 

standards unless those standards would be ineffective and inappropriate. Specifically, 

Article 2.4 states, 

“Where technical regulations are required and relevant international standards 

exist or their completion is imminent, Members shall use them, or the relevant 

parts of them, as a basis for their technical regulations except when such 

international standards or relevant parts would be an ineffective or inappropriate 

means for the fulfilment of the legitimate objectives pursued, for instance because 

of fundamental climatic or geographical factors or fundamental technological 

problems.”

2) How did EPA choose which non-attainment areas to display in Table 4 on page 25? Why

are areas that encompass some of the Nation’s larger “hub” airports (such as Boston, 

New York and Dallas-Fort Worth) not included?

3) It is acknowledged that section 233 of the Clean Air Act preempts States from adopting 

or enforcing any aircraft engine emissions standard unless such standard is identical to 

EPA’s. Nonetheless, because EPA is proposing to revise text in the Code of Federal 

Regulations with respect to this statutory preemption, additional discussion addressing 

EPA’s argument that this rule will not have federalism implications under Executive 

Order 13132 would be helpful. At a minimum, EPA should clarify the explanation 

provided on page 131 to remove some apparent inconsistencies in the text. Suggested 

revisions are: 

This action does not have federalism implications. It will not have substantial 

direct effects on the States, on the relationship between the national government 

and the States, or on the distribution of power and responsibilities among the 

various levels of government, as specified in Executive Order 13132. As 

discussed earlier, section 233 of the CAA preempts states from adopting or 

enforcing aircraft engine emission standards that are not identical to our 

standards. This rule proposes to revise the Code of Federal Regulations to more 

accurately reflect the statutory preemption established by the Clean Air Act. This 

rule does not impose any new preemption of merely modifies existing EPA 

aircraft engine emission standards and test procedures and therefore will merely 
Summary of Interagency Working Comments on Draft Language under 

EO12866 Interagency Review. Subject to Further Policy Review.

continue an existing preemption of State and local law. Thus, Executive Order 

13132 does not apply to this action.

4) In the discussion in the preamble about military engines, EPA states that it is "not 

proposing any specific provisions with respect to engines installed on military aircraft," 

explaining that such aircraft fall outside the scope of the emissions rules by operation of 

the regulatory language that brings covered aircraft within the rules (because the FAA 

rules do not require the certification of military engines). In the table on page 114, 

however, EPA suggests that proposed § 87.1 ("Definitions") contains a definition of 

"military aircraft." In fact, consistent with the earlier discussion, there is no such 

definition in § 87.1. 

5) Recommend revising the table to cite § 87.3 ("General applicability and requirements"), 

since it really pertains to applicability and since it doesn't actually refer to any particular 

definition in § 87.1. For consistency with the statutory FAA provisions, EPA may also 

wish to use the terminology in 49 USC § 40125(c), i.e. "aircraft owned or operated by the 

armed forces." The note in the table on page 114 might be revised to say, for instance, 

"The regulations of this part do not apply to aircraft owned or operated by the Armed 

Forces, including aircraft owned by the U.S. Coast Guard, as well as some other aircraft 

not owned by DoD." 

Whether or not EPA changes the cite or uses the terminology in 49 U.S.C., EPA's 

clarification in the preamble that military/armed forces aircraft are not covered by the 

rules and that such aircraft includes non-DoD aircraft is very helpful and much 

appreciated.

6) Recommend adding the words "that are required to be" to § 87.3(a) to read: "The 

regulations of this part apply to engines on all aircraft that are required to be certificated 

by FAA under 14 CFR part 34 except as specified...." In the preamble, EPA points out 

that manufacturers sometimes voluntarily certify engines that FAA does not require to be 

certificated and clarifies that it is EPA's intent to exclude engines which FAA does not 

require to be certificated, whether or not they are, in fact, certificated. The proposed 

language does not, however, say that and could be read that voluntary certification brings 

an engine within the purview of the regulations.

7) Recommend checking the internal cross-reference in §87.1 to ensure it is the correct cite.
Summary of Interagency Working Comments on Draft Language under 

EO12866 Interagency Review. Subject to Further Policy Review.

8) The draft rule contains provisions that may exceed reasonable interpretations of the 

statutory phrase “standards applicable to the emission of any air pollutant” (standards). If 

everything in the draft rule is considered a standard, an obligation would be created under 

CAA section 7572 for other agencies besides EPA to adopt and implement through their 

authorities. 

9) The EPA has proposed that a new annual report be submitted by engine manufacturers 

detailing the production of various engine models. Much of this information is available 

elsewhere. It is unclear whether the report can be viewed as a standard, and there does 

not appear to be a clear regulatory need for the report. Can EPA provide a clear rationale 

for why this report would be required, or consider not requiring this report? What 

specifically would the information be used for? Would collecting this information 

require approval under the Paperwork Reduction Act? 

10) The EPA has proposed a new “exemption” process under which manufacturers could 

continue to produce certain engines after the standards have changed. In general, 

industry usage of exemptions has remained low. The new process includes joint filings 

and unclear lines of authority and decision. It appears inconsistent in its use of terms that 

are well known in the industry, and attaches new concepts to them. No attempt has been 

made to detail the costs of the new process to other agencies, or to industry applicants. 

11) Similarly, the EPA proposes a new designation of “exempt-spare” engines that may be 

produced outside of production limits. The draft rule does not account for how this 

would impact certification processes and regulations of other agencies. The draft rule 

does not acknowledge the regulatory requirements or their costs that would fall on other 

agencies from adopting a new category of engine marking, and a new system by which 

the EPA expects them to be traceable. The concept of installing a “spare” engine 

presumes there is a system in place by which individual engines are tracked on individual 

aircraft by operations. The reality is that there is no such system in place to track engines 

with this new designation. The rule contains no acknowledgement of the cost that could 

result from a full consideration of such a requirement, including the tremendous cost on 

the FAA to promulgate and implement such a system.

12) EPA requests comment on a proposed “voluntary” emissions credit program. EPA has 

not acknowledged the lack of regulatory infrastructure on which to overlay such a 

program, or the fact that they intend for other agencies to administer it under its own 

regulations. Moreover, the offset program applies to engine manufacturers getting credit 

for producing a certain number of better engines in trade for ones that pollute more. 
Summary of Interagency Working Comments on Draft Language under 

EO12866 Interagency Review. Subject to Further Policy Review.

However, manufacturers do not know or control where their engines are operated, nor 

can the presumption be made that all are operated the same amount, producing a 

comparable amount of pollutant. The idea is based on an unstated presumption that there 

will be some benefit in the United States, or even in certain domestic areas. It is further 

tied into the unclear exemption process described previously. The cost of such a system 

is not described, nor is the presumed benefit of its existence. 

13) It is unclear why EPA is proposing to include ICAO guidance material (known as the 

Environmental Technical Manual or ETM for emissions) in the regulatory text. Adoption 

of international guidance material eliminates valid means of regulatory guidance already 

in place, changes it from advisory to mandatory (which was not ICAO’s intent) and 

eliminates compliance flexibility. A clear example is EPA’s proposal regarding what 

constitutes a derivative engine, which was clearly intended as guidance. No accounting 

for costs to other Agencies for implementing this requirement or industry compliance is 

accounted for. From a broader governmental perspective, this is an issue that goes 

beyond emissions, and would set a dangerous precedent. ICAO guidance material is not 

designed to function as mandatory regulation, and often embodies compromises that the 

U.S. agrees to only because it is adopted as guidance. If the U.S. turns guidance into 

regulations, it could tempt others to adopt, as regulations, ICAO guidance material that 

we object to. It would also undermine countries' willingness to adopt guidance material 

in the future.

14) In discussing the inclusion of ICAO materials, the draft rule engages in a discussion of 

“commercial” and “non-commercial” aircraft engines. The distinction between an engine 

used in commercial operation vs. non-commercial operation has no basis in the reality of 

regulated aircraft operations. An individual aircraft, for example, can switch status 

between flights. From a broader perspective, creating commercial and non-commercial 

definitions by classes of equipment rather than usage would also set a dangerous 

precedent, and would conflict with existing statutory and regulatory definitions.

15) The draft rule includes the adoption of technical appendices to ICAO standards and 

recommended practices. EPA’s adoption of these standards through incorporation by

reference (IBR) is inappropriate as there are legal implications of proper notice, the 

requirement to access a foreign publication to properly understand the requirements of a 

codified standard, and even language and format. There are also issues of cost in adopting 

the technical changes that the EPA does not acknowledge. 
Summary of Interagency Working Comments on Draft Language under 

EO12866 Interagency Review. Subject to Further Policy Review.

16) In several places, the proposed rule discusses military aircraft engines. While certain 

engine manufacturers certify engines that have both military and civilian applications, 

these are generally treated as civilian and under existing regulatory authorities. If the 

EPA finds that their authority extends to engines produced only for installation on 

military airplanes, then that regulation should remain within their sole jurisdiction and 

not be considered a standard that other agencies will adopt or enforce. 

17) It is several reviewers’ view that the EPA draft would require another federal agency to 

change its regulatory approach, add scope and costs to regulatory oversight with unclear 

benefits, incorporate practices not endorsed by aviation’s international standard-setting 

body, and produce confusion and misunderstanding in a global industry. There is no 

acknowledgment of the costs associated with such regulations, the changes to the current 

regulations, the burdens placed on other agencies for adoption and implementation, and 

no consideration of what benefits from the changes might accrue. If the EPA chooses to 

adopt them as its regulations alone, the provisions would be at considerable odds with the 

current regulatory system of aircraft engine certification in place under existing

regulations. One approach at least one reviewer recommends would be for EPA to limit

its rulemaking proposal to adopting only the ICAO oxides of nitrogen (NOx) emissions 

standards agreed upon at the CAEP/6 and CAEP/8 meetings. This approach could be 

implemented similarly to other historical ICAO CAEP outcomes.

18) The proposed rule does not indicate the fact that this EPA CAA rulemaking is subject to 

CAA section 307(d), 42 USC 7607(d). 

19) “...§87.44 Reporting CO2 emissions. (a)(1) For any type certificates involving 

compliance with NOx emission standards that are issued on or after January 1, 2014, you 

must report CO2 emissions to the Designated EPA Program Officer. You may include 

this information in the certification report described in §87.42 or in a separate 

submission.

(2) For any type certificates involving compliance with NOx emission standards that are 

issued before January 1, 2014, you must report CO2 emissions along with your emission 

levels of regulated NOx to the Designated EPA Program Officer. 

(b) Determine CO2 emission rates by direct measurement or by calculation from measured 

fuel mass flow rates for CO2 emissions from fossil and biogenic sources separately. These 

methods are described in Appendices 3 and 5 to ICAO Annex 16 (incorporated by reference 

in §87.8). Report CO2 emissions separately for each operating mode. If you test more than 

one engine, report the average value of CO2 emissions for each operating mode. Round CO2
Summary of Interagency Working Comments on Draft Language under 

EO12866 Interagency Review. Subject to Further Policy Review.

emissions of CO2 emissions from fossil and biogenic sources to the nearest whole gram and 

gram/kilonewton...”

Typos

Page 12: Specifically, reports would be required for turbofan engines with rated thrusts 

greater than 26.7 kN , which are subject to gaseous emission and smoke standards.....

Page 15: States may ban the use of any aircraft within their airspace that does not meet 

ICAO standards. Second, States are required to recognize the airworthiness certificates of 

any State whose standards are at least as stringent as ICAO’s standards, thereby assuring that 

it’s the aircraft of any member State will be permitted to operate in any other member State. 

Page 28: The ICAO NOx standards that with which we propose are proposing to align with

will help reduce ambient ozone and secondary PM levels and thus will help areas with 

airports achieve and/or maintain compliance with the National Ambient Air Quality

Standards (NAAQS).