Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 1 Specific Comments Specific comments and editorial suggestions have been written electronically in the draft, Final NPRM and may be viewed in Microsoft Word via the " track changes" view option. In many cases, discussion that is not intended as an editorial change, but an explanation, comment, or question are provided in italics and preceeded with the word " Note:". Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 2 ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 87 [ OAR 2002 0030; FRL XXXX X]

RIN 2060 AK01 Control of Air Pollution From Aircraft and Aircraft Engines; Emission Standards and Test Procedures AGENCY: Environmental Protection Agency ( EPA).

ACTION: Final rule.

SUMMARY: In this action, we are amending the existing United States regulations governing the exhaust emissions from new commercial aircraft gas turbine engines. Under the authority of section 231 of the Clean Air Act ( CAA), the Environmental Protection Agency ( EPA) is establishing new emission standards for oxides of nitrogen ( NOx) for newly certified commercial aircraft gas turbine engines with rated thrust greater than 26.7 kilonewtons ( kN).

This action adopts standards equivalent to the latest NOx standards of the United Nations International Civil Aviation Organization ( ICAO), and thereby brings the United States emission standards into alignment with the internationally adopted standards ( ICAO standards for newly certified engines were effective beginning in 2004). In addition, today's action amends the test Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 3 procedures for gaseous exhaust emissions to correspond to recent amendments to the ICAO test procedures for these emissions.

On [ Insert date 30 days after date of publication in the FEDERAL REGISTER], the new NOx standards will apply to newly certified gas turbine engines   those engines designed and certified after the effective date of the regulations ( for purposes of this action, the date of manufacture of the first individual production model means the date of type certification).

Newly manufactured engines of already certified models ( i. e., those individual engines that are part of an already certified engine model, but are built after the effective date of the regulations for such engines and have never been in service) will not have to meet these standards.

Today's amendments to the emission test procedures are those recommended by ICAO and are widely used by the aircraft engine industry. Thus, today's action will help establish consistency between U. S. and international standards, requirements, and test procedures. Since aircraft and aircraft engines are international commodities, there is commercial benefit to consistency between U. S. and international emission standards and control program requirements. In addition, today's action ensures that domestic commercial aircraft meet the current international standards, and thus, the public can be assured they are receiving the air quality benefits of the international standards.

DATES: This final rule is effective [ Insert date 30 days after date of publication in the FEDERAL REGISTER]. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 4 The incorporation by reference of certain publications listed in this regulation is approved by the Director of the Federal Register as of [ Insert date 30 days after date of publication in the FEDERAL REGISTER].

ADDRESSES: EPA has established a docket for this action under Docket ID No. OAR 2002

0030. All documents in the docket are listed in the EDOCKET index at http:// www. epa. gov/ edocket. Although listed in the index, some information is not publicly available, i. e., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically in EDOCKET or in hard copy at the Air Docket in the EPA Docket Center, EPA/ DC, EPA West,

Room B102, 1301 Constitution Ave., NW, Washington, DC. The Public Reading Room is open from 8: 30 a. m. to 4: 30 p. m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is ( 202) 566 1744, and the telephone number for the Air Docket is ( 202) 566 1742.

FOR FURTHER INFORMATION CONTACT: Mr. Bryan Manning, Assessment and Standards Division, Office of Transportation and Air Quality, Environmental Protection Agency,

2000 Traverwood Drive, Ann Arbor, MI 48105; telephone number: ( 734) 214 4832; fax number:

( 734) 214 4816; e mail address: manning. bryan@ epa. gov, or Assessment and Standards Division Hotline; telephone number: ( 734) 214 4636; e mail address: asdinfo@ epa. gov. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 5 SUPPLEMENTARY INFORMATION:

Does This Action Apply to Me?

Entities potentially regulated by this action are those that manufacture and sell commercial aircraft engines and aircraft in the United States, and the owners/ operators of such aircraft ( and accompanying engines) in the United States. Regulated categories include:

Category NAICSa Codes SIC Codesb Examples of potentially affected entities Industry .......... 336412 3724 Manufacturers of new aircraft engines Industry .......... 336411 3721 Manufacturers of new aircraft Industry .......... 481 4512 Scheduled air carriers, passenger and freight a North American Industry Classification System ( NAICS)

b Standard Industrial Classification ( SIC) system code This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this action. This table lists the types of entities that EPA is now aware could potentially be regulated by this action. Other types of entities not listed in the table could also be regulated. To determine whether your activities are regulated by this action, you should carefully examine the applicability criteria in 40 CFR 87.20 ( part 87). If you have any Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 6 questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding FOR FURTHER INFORMATION CONTACT section.

How Can I Get Copies of This Document and Other Related Information?

Docket. EPA has established an official public docket for this action under Docket ID No. OAR 2002 0030 at http:// www. epa. gov/ edocket. The official public docket consists of the documents specifically referenced in this action, any public comments received, and other information related to this action. The public docket does not include Confidential Business Information ( CBI) or other information whose disclosure is restricted by statute. The official public docket is the collection of materials that is available for public viewing at the Air Docket in the EPA Docket Center, ( EPA/ DC) EPA West, Room B102, 1301 Constitution Ave., NW,

Washington, DC. The EPA Docket Center Public Reading Room is open from 8: 30 a. m. to 4: 30 p. m., Monday through Friday, excluding legal holidays. The telephone number for the Reading Room is ( 202) 566 1742, and the telephone number for the Air Docket is ( 202) 566 1742.

Electronic Access. You may access this Federal Register document electronically through the EPA Internet under the " Federal Register" listings at http:// www. epa. gov/ fedrgstr/.

An electronic version of the public docket is available through EPA's electronic public docket and comment system, EPA Dockets. You may use EPA Dockets at http:// www. epa. gov/ edocket/ to view public comments, access the index listing of the contents of the official public docket, and to access those documents in the public docket that are available electronically. Although not all docket materials may be available electronically, you may still Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 7 access any of the publicly available docket materials through the docket facility identified above.

Once in the system, select " search," then key in the appropriate docket identification number.

Outline of This Preamble I. Introduction A. Brief History of EPA's Regulation of Aircraft Engine Emissions B. Interaction With the International Community C. EPA's Responsibilities Under the Clean Air Act II. Why is EPA Taking This Action?

A. Inventory Contribution B. Health and Welfare Effects 1. Ozone a. What Are the Health Effects of Ozone Pollution?

b. What Are the Current and Projected 8 hour Ozone Levels?

2. Particulate Matter a. What Is Particulate Matter?

b. What Are the Health Effects of PM2.5?

c. What Are The Current and Projected Levels?

C. Other Environmental Effects 1. Acid Deposition 2. Eutrophication and Nitrification 3. Plant Damage from Ozone Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 8 4. Visibility III. Aircraft Engine Standards A. What Are The NOx Standards For Newly Certified Engines?

1. Today's NOx Standards a. For Engines With a Pressure Ratio of 30 or less i. For engines with a maximum rated output of more than 89.0 kN ii. For engines with a maximum rated output of more than 26.7 kN but not more than 89.0 kN b. For Engines With A Pressure Ratio of More Than 30 But Less than 62.5 i. For engines with a maximum rated output of more than 89.0 kN ii. For engines with a maximum rated output of more than 26.7 kN but not more than 89.0 kN c. For Engines With a Pressure Ratio of 62.5 or More 2. NOx Standards of Newly Certified Mid and High Thrust Engines 3. NOx Standards for Newly Certified Low Thrust Engines 4. Rationale for Today's NOx Standards for Newly Certified Low, Mid, and High Thrust Engines 5. Future NOx Standards for Newly Certified Low, Mid, and High Thrust Engines B. Newly Manufactured Engines of Already Certified Models 1. What Is the Status of Engines?

2. What Are The Issues With Applying Today's NOx Standards to Newly Manufactured Engines of Already Certified Models? Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 9 IV. Amendments to Criteria on Calibration and Test Gases for Gaseous Emissions Test and Measurement Procedures V. Correction of Exemptions for Very Low Production Models VI. Coordination with FAA VII. Possible Future Aviation Emissions Reduction ( EPA/ FAA Voluntary Aviation Emissions Reduction Initiative)

VIII. Regulatory Impacts IX. Public Participation X. Statutory Provisions and Legal Authority XI. Statutory and Executive Orders Review A. Executive Order 12866: Regulatory Planning and Review B. Paperwork Reduction Act C. Regulatory Flexibility Analysis D. Unfunded Mandates Reform Act E. Executive Order 13132: Federalism F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments G. Executive Order 13045: Protection of Children from Environmental Health & Safety Risks H. Executive Order 13211: Actions that Significantly Affect Energy Supply, Distribution,

or Use I. National Technology Transfer Advancement Act J. Congressional Review Act Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 10 I. Introduction A. Brief History of EPA's Regulation of Aircraft Engine Emissions Section 231( a)( 2)( A) of the Clean Air Act ( CAA) directs the EPA Administrator to " issue proposed emission standards applicable to the emission of any air pollutant from any class or classes of aircraft or aircraft engines which in his judgment causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare'' ( 42 U. S. C.

7571( a)( 2)( A)). In addition, section 231( a)( 3) provides that after we propose standards, the Administrator shall issue such standards " with such modifications as he deems appropriate."

Under this authority EPA has conducted several rulemakings since 1973 establishing emission standards and related requirements for several classes ( commercial and general aviation engines)

of aircraft and aircraft engines. Most recently, in 1997 EPA promulgated NOx emission standards for newly manufactured gas turbine engines of already certified models1 ( those individual engines that are part of an already certified engine model, but are built after the 1In the proposal, we referred to such engines as already certified, newly manufactured engines or already certified engines; however, this terminology may need some clarification for the final rulemaking ( thus, we use the term " newly manufactured engines of already certified models"). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 11 effective date of the regulations for such engines and have never been in service) 2 and for newly certified gas turbine engines ( those engines designed and certified after the effective date of the regulations3). 4 In addition, EPA promulgated a carbon monoxide ( CO) emission standard for newly manufactured gas turbine engines in this same 1997 rulemaking. At the time, the 1997 rulemaking established consistency between the U. S. and international standards. ( See 40 CFR part 87 for a description of EPA's aircraft engine emission control requirements and 14 CFR part 34 for the Department of Transportation's regulations for ensuring compliance with these standards in accordance with section 232 of the Clean Air Act.)

B. Interaction With the International Community Since publication of the initial standards in 1973, EPA, together with the Federal Aviation Administration ( FAA), has worked with the International Civil Aviation Organization ( ICAO) on the development of international aircraft engine emission standards. ICAO was 2This does not mean that in 1997 we promulgated requirements for the re certification or retrofit of existing in use engines.

3Throughout this rule, the date of manufacture of the first individual production model means the date of type certification.

4U. S. EPA, " Control of Air Pollution from Aircraft and Aircraft Engines; Emission Standards and Test Procedures;" Final Rule, 62 FR 25356, May 8, 1997. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 12 established in 1944 by the United Nations ( by the Convention on International Civil Aviation,

the " Chicago Convention") "... in order that international civil aviation may be developed in a safe and orderly manner and that international air transport services may be established on the basis of equality of opportunity and operated soundly and economically." 5 ICAO's responsibilities include developing aircraft technical and operating standards, recommending practices, and generally fostering the growth of international civil aviation.

In 1972 at the United Nations Conference on the Human Environment, ICAO's position on the human environment was developed to be the following: "[ i] n fulfilling this role ICAO is conscious of the adverse environmental impact that may be related to aircraft activity and its responsibility and that of its member States to achieve maximum compatibility between the safe and orderly development of civil aviation and the quality of the human environment." Also, in 1972 ICAO established the position to continue "... with the assistance and cooperation of other bodies of the Organization and other international organizations... the work related to the development of Standards, Recommended Practices and Procedures and/ or guidance material dealing with the quality of the human environment..." 6 Insert. " At the 35th Assembly in October 5ICAO, " Convention on International Civil Aviation," Sixth Edition, Document 7300/ 6,

1980. Copies of this document can be obtained from the ICAO website located at www. icao. int.

6International Civil Aviation Organization ( ICAO), Foreword of " Aircraft Engine Emissions," International Standards and Recommended Practices, Environmental Protection, Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 13 2004, ICAO's 188 Contracting States affirmed that ICAO should continue to take the leadership role in all international civil aviation matters relating to the environment."

The United States is one of 188 participating member States of ICAO. 7 Under the basic ICAO treaty established in 1944 ( the Chicago Convention), a participating nation which elects not to adopt the ICAO standards must provide a written explanation to ICAO describing why a given standard is impractical to comply with or not in its national interest. 8 ICAO standards Annex 16, Volume II, Second Edition, July 1993. Copies of this document can be obtained from the ICAO website located at www. icao. int.

7As of June 20, 2002 there were 188 Contracting States according to the ICAO website located at www. icao. int. ( repeated in text, above)

8Text of Article 38 of Chicago Convention:

Any State which finds it impracticable to comply in all respects with any such international standard or procedure, or to bring its own regulations or practices into full accord with any international standard or procedure after amendment of the latter, or which deems it necessary to adopt regulations or practices differing in any particular respect from those established by an international standard, shall give immediate notification to the International Civil Aviation Organization of the differences between its own practice and that established by the international standard . . . . In any such case, the Council shall make immediate notification to all other states of the difference which exists between one or more features of an international standard and the corresponding national practice of that State. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 14 require States to provide written notification and failure to provide such notification could have negative consequences as detailed below.

If a Contracting State files a written notification indicating that it does not meet ICAO standards, other Contracting States are absolved of their obligations to " recognize as valid" the certificate of airworthiness issued by that Contracting State, since that certificate will not have been issued under standards " equal to or above" ICAO standards. In other words, other Contracting States do not have to allow aircraft belonging to that Contracting State to travel through their airspace. 9 Further, if it fails to file a written notification, it will be in default of its obligations, and risks mandatory exclusion of its aircraft from the airspace of other Contracting States and the loss of its voting power in the Assembly and Council. 10 The Chicago Convention does not require all Contracting States to adopt identical airworthiness standards. Although the Convention urges a high degree of uniformity, it is expected that States will adopt their own airworthiness standards, and it is anticipated that some 9Text of Article 33 of Chicago Convention:

Certificates of airworthiness and certificates of competency and licenses issued or rendered valid by the contracting State in which the aircraft is registered, shall be recognized as valid by the other contracting States, provided that the requirements under which such certificates or licenses were issued or rendered valid are equal to or above the minimum standards which may be established from time to time pursuant to this Convention.

10Articles 87 and 88 of Chicago Convention. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 15 states may adopt standards that are more stringent than those agreed by ICAO. However,

because any State can ban use within its airspace of any aircraft that does not meet ICAO standards, States that wish to use aircraft in international air transportation have agreed to adopt standards that meet or exceed the stringency levels of ICAO standards. 11 Because States are required to recognize certificates of any State whose standards meet or exceed ICAO standards, a State is assured its aircraft will be permitted to operate in any other Contracting State if its standards meet or exceed the minimum stringency levels of ICAO standards.

As long as a participating nation of ICAO adopts aircraft emission standards that are equal to or more stringent than ICAO's standards, the certificates of airworthiness for such nations are valid. Thus, aircraft belonging to countries with more stringent standards are permitted to travel through the airspace of other countries without any restriction. To ensure operation internationally without constraints, a participating nation which elects to adopt more stringent standards is obligated to notify ICAO of the differences between its standards and ICAO standards. 12 However, if a nation sets tighter standards than ICAO, air carriers not based in that nation ( foreign flag carriers) would only be required to comply with the ICAO standards.

The ICAO Council's Committee on Aviation Environmental Protection ( CAEP)

undertakes ICAO's technical work in the environmental field. The CAEP is responsible for 11Article 33 of Chicago Convention.

12Article 38 of Chicago Convention. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 16 evaluating, researching, and recommending measures to the ICAO Council that address the environmental impact of international civil aviation. CAEP is composed of various Study Groups, Work Groups, Committees and other contributing memberships that include atmospheric, economic, aviation, environmental, and other professionals committed to ICAO's previously stated position regarding aviation and the environment. At CAEP meetings, the United States is represented by the FAA, which plays an active role at these meetings ( see section VI for further discussion of FAA's role). EPA has historically been a principal participant in the development of U. S. policy in ICAO/ CAEP and other international venues,

assisting and technically advising FAA on aviation emissions matters. If the ICAO Council adopts a CAEP proposal to adopt a new environmental standard, it then becomes part of the ICAO standards and recommended practices ( Annex 16 to the Chicago Convention). 13 On June 30, 1981, the ICAO Council adopted its first international standards and recommended practices covering aircraft engine emissions. 14 These standards limit aircraft engine emissions of NOx, CO, and hydrocarbons ( HC), in relation to other engine performance 13ICAO, " Aircraft Engine Emissions," International Standards and Recommended Practices, Environmental Protection, Annex 16, Volume II, Second Edition, July 1993. Copies of this document can be obtained from ICAO ( www. icao. int).

14ICAO, Foreword of " Aircraft Engine Emissions," International Standards and Recommended Practices, Environmental Protection, Annex 16, Volume II, Second Edition, July 1993. Copies of this document can be obtained from ICAO ( www. icao. int). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 17 parameters, and are commonly known as stringency standards. On March 24, 1993, the ICAO Council approved a proposal adopted at the second meeting of the CAEP ( CAEP/ 2) to tighten the original NOx standard by 20 percent and amend the test procedures. At the next CAEP meeting ( CAEP/ 3) in December 1995, the CAEP recommended a further tightening of 16 percent and additional test procedure amendments, but on March 20, 1997 the ICAO Council rejected this stringency proposal and approved only the test procedure amendments. At its next meeting ( CAEP/ 4) in April 1998, the CAEP adopted a similar 16 percent NOx reduction proposal, which the ICAO Council approved on February 26, 1999.15 The CAEP/ 4 16 percent NOx reduction standard applies to new engine designs certified after December 31, 2003 ( i. e., it applies only to newly certified engines, rather than to newly manufactured engines of already certified models). 16,17 15 International Civil Aviation Organization ( ICAO), Aircraft Engine Emissions, Annex 16, Volume II, Second Edition, July 1993, Amendment 4 effective on July 19, 1999. Copies of this document can be obtained from ICAO ( www. icao. int).

16These NOx standards will be interchangeably be referred to as the 1998 CAEP/ 4 standards and the 1999 ICAO standards throughout this Notice.

17Newly manufactured engines of already certified models are those individual engines that are part of an already certified engine model, but are built after the effective date of the regulations for such engines and have never been in service. This does not mean the recertification or retrofit of existing in use engines . Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 18 As discussed earlier, in 1997 EPA amended its regulations to adopt the 1981 ICAO NOx and CO emission standards, as well as the NOx emission standards and test procedures revised by ICAO in 1993. As discussed above, the U. S. has an obligation under the Convention on International Civil Aviation to notify ICAO regarding differences between U. S. standards and ICAO standards, and to provide notification on the date by which the program requirements will be consistent. In response to the recent actions by ICAO and for the reasons discussed below, in today's rulemaking EPA is adopting standards for newly certified engines that are equivalent to ICAO's 1999 amendment to the NOx emission standard and the test procedure changes approved by ICAO in 1997, and EPA is adopting other technical amendments to further align EPA and ICAO requirements.

C. EPA's Responsibilities Under the Clean Air Act As discussed earlier, section 231 of the CAA directs EPA, from time to time, to propose aircraft engine emission standards applicable to any air pollutant from classes of aircraft engines which in its judgement may reasonably be anticipated to endanger public health or welfare.

Section 231( a)( 3) provides that after we propose standards, the Administrator shall issue such standards " with such modifications as he deems appropriate." In addition, EPA is required to ensure, in consultation with the Secretary of Transportation, that such standards' effective dates permit the development of necessary technology, giving appropriate consideration to compliance cost. Also, EPA must consult with the FAA before proposing or promulgating emission Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 19 standards. ( See section VI of today's proposal for further discussion of EPA's coordination with FAA and FAA's responsibilities under the CAA.)

In addition, section 233 of the CAA vests authority to implement emission standards for aircraft or aircraft engines only in EPA in consultation with the Secretary of Transportation. 18 States are preempted from adopting or enforcing any standard respecting aircraft engine emissions unless such standard is identical to EPA's standards. In addition to this express preemption, the comprehensive scheme established by CAA sections 231 and 232 for regulation of aircraft emissions by EPA and the U. S. Department of Transportation demonstrates federal preemption of the entire field. See Washington V. General Motors Corp., 406 U. S. 109, 114 ( 1972) ( stating that Congress has " preempted the field so far as emissions from airplanes are concerned") 19In addition, federal aviation law preempts the states from taking any action,

including action related to aircraft emissions that would necessarily have the direct or indirect effect of restricting aircraft operations.

II. Why Is EPA Taking This Action?

18CAA section 233 entitled " State Standards and Controls'' states that " No State or political subdivision thereof may adopt or attempt to enforce any standard respecting emissions of any air pollutant from any aircraft or engine thereof unless such standard is identical to a standard applicable to such aircraft under this part.'' Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 20 As mentioned above, section 231( a)( 2)( A) of the CAA authorizes the Administrator to " from time to time, issue proposed emission standards applicable to emission of any air pollution from any class or classes of aircraft or aircraft engines which in his judgment causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare."

One of the principal components of aircraft exhaust emissions is NOx. NOx is a precursor to the formation of ozone. 19 Many commercial airports are located in urban areas and many of these areas have ambient ozone levels above the National Ambient Air Quality Standards ( NAAQS) for ozone ( i. e., they are in nonattainment for ozone). NOx emissions from aircraft also contribute to adverse health effects associated with ambient concentrations of PM. This section discusses the contribution of aircraft engines to the national NOx and PM emissions inventories and the health and welfare impacts of these emissions.

A. Inventory Contribution 20Ground level ozone, the main ingredient in smog, is formed by complex chemical reactions of volatile organic compounds ( VOC) and NOx in the presence of heat and sunlight.

Standards that reduce NOx emissions will help address ambient ozone levels. They will also help reduce PM levels as NOx emissions can also be part of the secondary formation of PM.

However, these reductions may be offset by potential tradeoffs between NOx and PM reduction at the source. See Section II. B below. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 21 EPA's estimate of the contribution of aircraft to national NOx and PM emission inventories is set out in Table II 1. Note that this table provides the inventory contributions only for 2001, and therefore does not take into account the impacts of our recent mobile source emission control programs for highway vehicles and nonroad engines and equipment which will go into effect in the coming years. 20 . Those new standards are expected to reduce NOx and PM emissions from highway and nonroad engines by 90 percent or more on a per engine basis. Nor does the table account for aviation's reduced NOx emissions due to slower growth and changes in fleet composition Nonetheless, as these new programs go into effect, it is probable the relative size of the contribution of aircraft to national NOx and PM levels may increase due to the decrease in the contribution of those other mobile sources.

Table II 1 Annual NOx and PM Baseline Emission Levelsa From EPA's National Air Quality and Emissions Trends Report, August 2003 ( Short Tons, 2001)

Category NOx ( Thous. Tons) PM Aircraftb, c 81 0.7% 2 0.4%

Nonroad 4,075 32.8% 288 63.7%

Highway 8,249 66.5% 162 35.8%

Total Mobile Source 12,405 452 aSource: U. S. EPA, " Average Annual Emissions, All Criteria Pollutants Years Including 1970  2001," Updated August 2003. This document is available at http:// www. epa. gov/ ttnchie1/ trends/ and Docket No. OAR 2002 0030.

20For additional information on the inventory impacts of our new rules, see Tables IV A

1 and IV A 2 in our Advance Notice of Proposed Rulemaking for an additional tier of standards for locomotives and marine diesel engines below 30 liters per cylinder displacement ( 69 FR 39276, June 29, 2004). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 22 bThese aircraft emissions are a conservative estimate as they reflect military operations only at FAA and FAAcontracted facilities and not at military bases. See the following memo for further discussion of the contribution of military aircraft to total aircraft emissions: U. S. EPA, " Earlier and Current Estimates of Military Aircraft Emissions," Memorandum to Docket OAR 2002 0030 from Bryan Manning, September 30, 2003. [ MAY NEED TO UPDATE THIS MEMO Note: We agree.]. c Mistakenly, the national aircraft PM emissions in the 2003 Trends Report did not include commercial aircraft estimates, and thus, these aircraft PM emissions are a conservative estimate. This error will be corrected in the next Trends Report.

Aircraft emissions are emitted from a variety of aircraft types used for public, private,

and military purposes including commercial aircraft, air taxis, general aviation, and military aircraft. 21 Commercial aircraft emissions contribute from 70 to 85 percent of the NOx aircraft emissions in the U. S. The high end of this range represents commercial aircraft's fraction of national aircraft NOx emissions when current estimates for all aircraft types ( commercial aircraft,

21Commercial aircraft include those aircraft used for scheduled service transporting passengers, freight, or both. Air taxis also fly scheduled service carrying passengers, freight or both, and have played an increasing role in the operations of the U. S. aviation system. By 2015,

such operations are forecast to represent 54% of operations. General aviation includes most other aircraft used for recreational flying and personal transportation. Aircraft that support business travel, usually on an unscheduled basis, are included in the category of general aviation.

Military aircraft cover a wide range of sizes, uses, and operating missions. While they are often similar to civil aircraft, they are handled separately ( this needs clarification, e. g., data regarding military flights and emissions are accounted for through separate dabases or models???) because they often operate primarily out of military bases and frequently have distinctive flight profiles. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 23 air taxis, general aviation, and military aircraft) are added together. 22 The lower end of the range is commercial aircraft's contribution of NOx aircraft emissions in the U. S. when combining earlier23 military aircraft estimates with current emission estimates for the three other aircraft types ( the earlier and current estimates were based on different methods or models for calculating aircraft emissions in 2001). This range was provided since the current estimates of military aircraft emission have limitations   i. e., military aircraft estimates are a conservative 22U. S. EPA, " Average Annual Emissions, All Criteria Pollutants Years Including 1970

2001," Updated August 2003. This document is available at http:// www. epa. gov/ ttnchie1/ trends/

and Docket No. OAR 2002 0030.

U. S. EPA, " Documentation for Aircraft, Commercial Marine Vessel, Locomotive, and other Nonroad Components of the National Emissions Inventory, Volume I  Methodology,"

Prepared for EPA by Eastern Research Group, Inc., October 7, 2003. A copy of this document can be found in Docket No. OAR 2002 30.

23The earlier military estimates are based on emission inventories from the Final Rule for Control of Emissions from Land based Nonroad Diesel Engines, 69 FR 38958, June 29, 2004.

Also, see the following memorandum for further discussion of the contribution of military aircraft to total aircraft emissions and related references: U. S. EPA, " Earlier and Current Estimates of Military Aircraft Emissions," Memorandum to Docket OAR 2002 0030 from Bryan Manning, September 30, 2003. [ MAY NEED TO UPDATE THIS MEMO Note: We agree.]. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 24 estimate as they reflect military operations only at FAA and FAA contracted facilities and not at military bases. For a discussion on obtaining improved military aircraft emission estimates, see Section 5 of the Summary and Analysis of Comments for this rulemaking. ( See the following memorandum for a further description of the contribution of military aircraft to total aircraft emissions: U. S. EPA, " Earlier and Current Estimates of Military Aircraft Emissions,"

Memorandum to Docket OAR 2002 0030 from Bryan Manning, September 30, 2003. [ MAY NEED TO UPDATE THIS MEMO Note: We agree. ].)

While the current contribution of aircraft to nationwide NOx . is less than one percent,

their contribution on a local level, especially in areas containing or adjacent to airports can be much larger and is also expected to grow. This is illustrated by EPA's 1999 study that examined NOx emissions from aircraft for ten cities: Atlanta, Boston Lawrence Worcester, Charlotte

Gastonia, Chicago Gary Lake County, Houston Galveston Brazoria, New York New Jersey

Long Island, Philadelphia, Phoenix, Los Angeles Air Basin and Washington D. C. 24 Nineteen 24U. S. EPA, " Evaluation of Air Pollutant Emissions from Subsonic Commercial Jet Aircraft," April 1999, EPA420 R 99 013. A copy of this document is available at http:// www. epa. gov/ otaq/ aviation. htm. It can also be found in Docket No. OAR 2002 0030,

Document No. OAR 2002 0030 0002. The FAA believes this report has significant limits as a reference in this NPRM. In generating its NOx forecasts, tThe study failed to account for infrastructure limitations, runway availability, and airport growth rates; used old emissions factors to characterize part of the 2010 fleet; ignored fleet turnover to cleaner engines during Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 25 airport facilities with significant commercial jet aircraft activity were identified within these selected areas. . On average for these ten cities, commercial aircraft's contribution was expected to increase from about 2 percent of regional total NOx emissions in 1990 to about 5 percent in 2010.25 Note: The sentence doesn't offer any clarity or context and should be footnote 24. Add, as a footnote for the previous sentence along with footnote 24: " The FAA disagreed with the conclusions of the ten cities report, and therefore, questioned its use as a reference in this NPRM. Among the problems in the report, beyond the fact that there have been significant effects on commercial airline operations since September 11, 2001, are a failure to account for growth constraints such as infrastructure limitations, funding limitations, runway availability, and airport growth rates; use of old emissions factors to characterize part of the 2010 fleet, fleet turnover to cleaner engines that was not accounted for, adoption of newer ICAO emissions standards; mixing height assumptions; and times in mode accuracy."

It should be noted that the above study of the impacts of airports on regional air quality was conducted before the tragic events of September 11, 2001, and the economic downturn in the aircraft transportation sector and resulting slowing of emissions growth. A report by the Department of Transportation in 2003 indicated that the combination of the September 11, 2001 terrorist attacks and cut backs in business travel have had a significant effect on air the time period; did not account for adoption of newer ICAO emissions standards; used incorrect (?) mixing height assumptions; and times in mode accuracy (?). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 26 transportation demand. 25 The FAA expects the demand for air travel to recover and then continue a long term trend of annual growth, though from a lower base and at a slower rate in the United States. 26 Thus, there is both a short term decrease in aircraft transportation activity as a result of 9/ 11, with negative growth for the period 2001 to 2005 and associated decreases in aircraft emission contributions and lower emissions growth than originally anticipated over the time period assessed.. This is illustrated in Table II 2, which compares the results of an earlier,

pre 9/ 11 FAA activity forecast to a recent, post 9/ 11 forecast. As operations increase, the inventory impact of these aircraft on national and local NOx and PM inventories and on ozone and ambient PM levels will also increase. .

Table II 2   FAA Terminal Area Forecast Summary Report of Nationwide Air Carrier Operationsa, b aSource: U. S. FAA, " APO Terminal Area Forecast Summary Report," Aircraft Operations, December 14, 2000; and " APO Terminal Area Forecast Summary Report  Forecast Issued January 2004," as of November 2, 2004. See the following FAA website: http:// www. apo. data. faa. gov/ faatafall. HTM. A copy of these reports can be found in Docket No. OAR 2002 0030. bOperations means the number of arrivals and departures ( www. apo. data. faa. gov/ gloss. html).

25U. S. Department of Transportation, Office of Inspector General, " Airline Industry Metrics," CC 2203 007, January 7, 2003. A copy of this document can be found in Docket No.

OAR 2002 0030, Document No. OAR 2002 0030 0012.

26U. S. General Accounting Office, " Aviation and the Environment: Strategic Framework Needed to Address Challenges Posed by Aircraft Emissions," GAO 03 252, February 2003.

This document is available at www. gao. gov/ cgi bin/ getrpt? GAO 03 252, and it can also be found in the Docket No. OAR 2002 0030, Document No. OAR 2002 0030 0005. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 27 cThe change in operations from 2000 to 2002 was + 4.7% for the 12/ 14/ 00 forecast, and it was  9.2% for the 1/ 04 forecast. The data in Table II 2 show that prior to 9/ 11 growth in air carrier operations was expected to increase by 34 percent from 2000 to 2015. The revised growth forecast for this period estimates that aircraft activity will now increase only 22% in the period 2010 2015. In fact, the originally anticipated operation levels in 2015 are now forecast not to be reached until 2020.

Aircraft emissions are a large portion of total emissions associated with airports. Air pollutants resulting from airport operations are emitted from several types of sources including aircraft main engines and auxiliary power units ( APUs); ground support equipment ( GSE),

which includes vehicles such as aircraft tugs, baggage tugs, fuel trucks, maintenance vehicles,

and other miscellaneous vehicles used to support aircraft operations; and ground access vehicles ( GAV), which include vehicles used by passengers, employees, freight operators, and other persons to enter and leave an airport. EPA estimates that aircraft engines comprise approximately 45 percent of total air pollutant emissions from airport operations. GAV account for another 45 percent and APUs and GSE combined make up the remaining 10 percent. 29 Note:

29The California FIP, signed by the Administrator 2/ 14/ 95, is located in EPA Air Docket A 94 09, item number V A 1. The FIP was vacated by an act of Congress before it became effective. In addition, the 1997 EPA Draft Final Report entitled, " Analysis of Techniques to Reduce Air Emission at Airports" ( prepared by Energy and Environmental Analysis, Inc),

estimated that for the four airports studied ( which are large air traffic hubs) on average aircraft comprise approximately 35 percent of NOx emissions from airport operations; GAV account for Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 28 The footnote indicates that aircraft average 35%, GAV 35%, and APUs and GSE make up the balance. Is the difference between these two references a typographical error? Since EPA has established stringent emission standards for GAVs and other highway and nonroad vehicles used at airports, overall emissions from these vehicles will continue to decline for many years. This means that aircraft will contribute an increasing portion of total emissions associated with airport operations.

B. Health and Welfare Effects NOx emissions from commercial aircraft and other mobile and stationary sources contribute to the formation of ozone. In addition, NOx emissions at low altitude also react in the atmosphere to form secondary particulate matter ( PM2.5), particularly ammonium nitrate, and they contribute to regional haze. 30 The NOx standards adopted in this rule will help reduce ambient ozone and PM levels and thus will help areas with airports achieve and/ or maintain compliance with the NAAQS for ozone and PM. The NOx standards will also help areas reduce another 35 percent, and APUs and GSE contribute about 15 percent each for the remaining 30 percent. This document can be found in Docket No. OAR 2002 0030, Document No. OAR

2002 0030 0071.

30As described later in section II. B. 2, fine particles refer to those particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers ( also known as PM2.5). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 29 regional haze and increase visibility in places where people live, work, and recreate. 31 In the following section we discuss the health and welfare effects of ozone and PM emissions Note:

Given the overall contribution of aircraft emissions to air quality problems, further dilution in the conversion rates of NOx into ozone and PM, reductions in regional haze and increased visibility may not be a reasonable expectation.

1. Ozone a. What are the health effects of ozone pollution?

NOx is a precursor in the photochemical reaction which forms tropospheric ozone.

Ground level ozone, the main ingredient in smog, is formed by complex chemical reactions of VOCs and NOx in the presence of heat and sunlight. The health effects of ozone pollution are described in detail in EPA's Air Quality Criteria Document for Ozone and Other Photochemical Oxidants and are also described in the Final Regulatory Analysis for our recent Clean Air Nonroad Diesel rule. 32 The following is a summary of those effects.

31The NOx standards being set today will also help reduce levels of nitrogen dioxide ( NO2), for which NAAQS have been established. Currently, every area in the United States has been designated to be in attainment with the NO2 NAAQS.

32U. S. EPA ( 1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,

EPA/ 600/ P 93/ 004aF. This document can be found in Docket No. A 99 06. Document Nos. II Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 30 Ozone can irritate the respiratory system, causing coughing, throat irritation, and/ or uncomfortable sensation in the chest. In addition, ozone can reduce lung function and make it more difficult to breathe deeply, and breathing may become more rapid and shallow than normal,

thereby limiting a person's normal activity. Ozone also can aggravate asthma, leading to more asthma attacks that require a doctor's attention and/ or the use of additional medication. In addition, ozone can inflame and damage the lining of the lungs, which may lead to permanent changes in lung tissue, irreversible reductions in lung function, and a lower quality of life if the inflammation occurs repeatedly over a long time period. People who are of particular concern with respect to ozone exposures include children and adults who are active outdoors. Those people particularly susceptible to ozone effects are people with respiratory disease, such as asthma, people with unusual sensitivity to ozone, and children. Beyond its human health effects,

ozone has been shown to injure plants, which has the effect of reducing crop yields and reducing productivity in forest ecosystems. 33, 34 A 15 to 17. U. S. EPA ( 2004). Final Regulatory Assessment: Control of Emissions from Nonroad Diesel Engines, EPA420 R 04 007. This document can be found in Docket No. OAR

2002 0030, Document No. OAR 2002 0030 0128.

33U. S. EPA ( 1996). Review of National Ambient Air Quality Standards for Ozone,

Assessment of Scientific and Technical Information, OAQPS Staff Paper, EPA 452/ R 96 007.

Docket No. A 99 06. Document No. II A 22. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 31 New research suggests additional serious health effects beyond those that were known when the ozone NAAQS was revised in 1997. Since 1997, over 1,700 new health and welfare studies relating to ozone have been published in peer reviewed journals. 35 Many of these studies investigate the impact of ozone exposure on such health effects as changes in lung structure and biochemistry, inflammation of the lungs, exacerbation and causation of asthma, respiratory illness related school absence, hospital and emergency room visits for asthma and other respiratory causes, and premature mortality. EPA is currently evaluating these and other studies as part of the ongoing review of the air quality criteria and NAAQS for ozone. A revised Air Quality Criteria Document for Ozone and Other Photochemical Oxidants will be prepared in consultation with EPA's Clean Air Science Advisory Committee ( CASAC). Key new health information falls into four general areas: development of new onset asthma, hospital admissions for young children, school absence rate, and premature mortality. In all, the new studies that have become available since the 8 hour ozone standard was adopted in 1997 continue to 34U. S. EPA ( 1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,

EPA/ 600/ P 93/ 004aF. Docket No. A 99 06. Document Nos. II A 15 to 17.

35New Ozone Health and Environmental Effects References, Published Since Completion of the Previous Ozone AQCD, National Center for Environmental Assessment, Office of Research and Development, U. S. Environmental Protection Agency, Research Triangle Park, NC 27711 ( 7/ 2002) Docket No. A 2001 28, Document II A 79. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 32 demonstrate the harmful effects of ozone on public health and the need for areas with high ozone levels to attain and maintain the NAAQS.

b. What are current and projected ozone levels?

There are currently two ozone NAAQS, an 8 hour standard and a 1 hour standard. The 8 hour ozone standard is met when the fourth highest daily maximum 8 hour average ozone concentration measured over a 3 year period is less than or equal to 0.085 parts per million ( ppm). The 1 hour ozone threshold value is 0.12 ppm, measured as a 1 hour average concentration. An area meets the 1 hour ozone NAAQS if there is no more than one day per year when the highest hourly value exceeds the threshold. The 1 hour ozone standard is being replaced by the 8 hour ozone standard and the 1 hour ozone standard will likely be revoked in June 2005.36 On June 15, 2004, the 8 hour ozone nonattainment designations became effective. 37 Nationwide, there are approximately 159 million people living in 126 areas that are designated as 36National Ambient Air Quality Standards for Ozone; Final Rule. 62 FR 38855 ( July 18,

1997).

37U. S. EPA, " Air Quality Designations and Classifications for the 8 hour Ozone National Ambient Air Quality Standards; Early Action Compact Areas With Deferred Effective Dates,"

Final Rule, 69 FR 23858 ( April 30, 2004). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 33 not attaining the 8 hour ozone NAAQS based upon the monitored data from 2001 2003 and other factors. The CAA defines a nonattainment area as an area that is violating an ambient standard or is contributing to a nearby area that is violating the standard. All or part of 474 counties are designated as nonattainment for the 8 hour ozone NAAQS. These counties are spread over wide geographic areas, including most of the nation's major population centers,

which include much of the eastern half of the U. S. and large areas of California. 38 From air quality modeling performed for the recent Clean Air Interstate Rule ( CAIR), 39 we anticipate that without emission reductions beyond those already required under promulgated regulation and approved State Implementation Plans ( SIPs), ozone nonattainment will likely persist into the future. With reductions from programs already in place, including the CAIR,

[ UPDATE IF CAIR DOESN'T COME OUT] the number of counties in the eastern U. S.

violating the ozone 8 hour standard is expected to decrease in 2015 to 26 counties where 43 million [ UPDATE WHEN CAIR COMES OUT] people are projected to live.

On June 2, 2003 ( 68 FR 32802), EPA issued a proposal for the implementation process to bring the nation's air into attainment with the 8 hour ozone NAAQS, including proposed requirements that States submit SIPs that address how areas will attain the 8 hour ozone 38A map that shows the current ozone, PM2.5, and federal Class I visibility areas and a list of affected counties can be found in Docket No. OAR 2002 0030.

39[ CITE NEEDS TO BE UPDATED WHEN CAIR IS FINALIZED  expected soon] Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 34 standard. 40 The second phase ( Phase II) of this proposed implementation process for the 8 hour ozone NAAQS will be finalized in the next few months, and it will describe the SIP submittal date requirements. ( Phase I of the proposed implementation process was finalized on April 30,

2004 ( 69 FR 23951), but it did not include these SIP submittal date requirements.) 41 The Act ( Title I, Part D) contains two sets of requirements for State plans implementing the national ozone air quality standards in nonattainment areas. Subpart 1 contains general requirements for SIPs for nonattainment areas for any pollutant, including ozone, governed by a NAAQS. Subpart 2 provides more specific requirements for ozone nonattainment SIPs. Under subpart 1, a state must demonstrate that its nonattainment areas will attain the ozone 8 hour standard as expeditiously as practicable but no later than five years from the date that the area was designated nonattainment. However, based on the severity of the air quality problem and the availability and feasibility of control measures, the Administrator may extend the attainment date " for a period of no greater than 10 years from the date of designation as nonattainment."

Based on these provisions, we expect that most or all areas covered under subpart 1 will attain the 8 hour ozone standard in the 2007 to 2014 time frame. For areas covered under subpart 2,

the maximum attainment dates provided under the Act range from 3 to 20 years after 40U. S. EPA, " Proposed Rule to Implement the 8 hour Ozone National Ambient Air Quality Standard," Proposed Rule, 68 FR 32802 ( June 2, 2003).

41 U. S. EPA, " Final Rule to Implement the 8 Hour Ozone National Ambient Air Quality Standard  Phase 1," Final Rule, 69 FR 23951 ( April 30, 2004). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 35 designation, depending on an area's classification. Thus, we anticipate that areas covered by subpart 2 will attain the 8 hour ozone standard in the 2007 to 2024 time period.

Since the emission reductions expected from the standards we are adopting in this rule will occur during the time period when areas will need to attain the standard under either option,

projected reductions in aircraft engine emissions will assist States in their efforts to attain and maintain the 8 hour NAAQS.

2. Particulate Matter a. What is Particulate Matter?

Particulate matter represents a broad class of chemically and physically diverse substances. It can be principally characterized as discrete particles that exist in the condensed ( liquid or solid) phase spanning several orders of magnitude in size. PM10 refers to particles with an aerodynamic diameter less than or equal to a nominal 10 micrometers. Fine particles refer to those particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers ( also known as PM2.5). The emission sources, formation processes, chemical composition,

atmospheric residence times, transport distances and other parameters of fine and coarse particles are distinct. This discussion focuses on fine PM since the NOx emitted by aircraft engines reacts in the atmosphere to form fine PM as discussed below.

Fine particles are directly emitted from combustion sources and are formed secondarily from gaseous precursors such as oxides of nitrogen ( NOx). Fine particles are generally composed of sulfate, nitrate, chloride, ammonium compounds, organic carbon, elemental carbon, Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 36 and metals. Aircraft engines emit NOx which reacts in the atmosphere to form secondary PM2.5 ( namely ammonium nitrate). Combustion of coal, oil, diesel, gasoline, and wood, as well as high temperature process sources such as smelters and steel mills, produce emissions that contribute to fine particle formation. Fine particles can remain in the atmosphere for days to weeks and travel through the atmosphere hundreds to thousands of kilometers. Thus emissions from aircraft, as well as those from other sources, could affect nonattainment areas far from their source. However, because of uncertainties surrounding aircraft PM formation and subsequent growth in the atmosphere, the relative impact is uncertain and further research is needed to characterize impact and suggest mitigation.

The relative contribution of various chemical components to PM2.5 varies by region of the country. Data on PM2.5 composition are available from the EPA Speciation Trends Network in 2001 and the Interagency Monitoring of PROtected Visual Environments ( IMPROVE) network in 1999 covering both urban and rural areas in numerous regions of the U. S. These data show that nitrates formed from NOx play a major role in the western U. S., especially in the California area where it is responsible for about a quarter of the ambient PM2.5 concentrations. 42 However,

the majority of NOx involved in this process does not come from aircraft. See detailed 42See the Regulatory Impact Analysis: " Final Regulatory Analysis: Control of Emissions from Nonroad Diesel Engines," EPA420 R 04 007, May 2004. This document is available at http:// www. epa. gov/ nonroad/ and in Docket No. OAR 2002 0030, Document No. OAR 2002

0030 0128. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 37 comments on pages 29 and 35. The relationship between this discussion and aircraft NOx is tenuous at best.

b. What Are the Health Effects of PM?

Scientific studies show ambient PM is associated with a series of adverse health effects.

These health effects are discussed in detail in the recently released EPA Criteria Document for PM. 43 They are also described in the Final Regulatory Analysis for our recent Clean Air Nonroad Diesel rule. 44 The following is a summary of those effects.

The health effects associated with short term variation in ambient particulate matter ( PM)

have been indicated by epidemiologic studies showing associations between exposure and increased hospital admissions for ischemic heart disease, heart failure, respiratory disease,

including chronic obstructive pulmonary disease ( COPD) and pneumonia. Short term elevations 43U. S. EPA, Air Quality Criteria for Particulate Matter ( OCT 2004), Volume I Document No. EPA600/ P 99/ 002aF and Volume II Document No. EPA600/ P 99/ 002bF. This document is available in Docket No. OAR 2002 0030, Document No. OAR 2002 0030 0129 and OAR 2002

0030 0130.

44U. S. EPA ( 2004). Final Regulatory Assessment: Control of Emissions from Nonroad Diesel Engines, EPA420 R 04 007. This document can be found in Docket No. OAR 2002

0030, Document No. OAR 2002 0030 0128. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 38 in ambient PM have also been associated with increased cough, lower respiratory symptoms, and decrements in lung function. Additional studies have associated changes in heart rate and/ or heart rhythm in addition to changes in blood characteristics with exposure to ambient PM.

Short term variations in ambient PM have also been associated with increases in total and cardiorespiratory mortality. Studies examining populations exposed to different levels of air pollution over a number of years, including the Harvard Six Cities Study and the American Cancer Society Study, suggest an association between exposure to ambient PM2.5 and premature mortality. 45, 46 Additionally, one long term study provides evidence for premature mortality specifically associated with PM generated by mobile sources47. Two studies further analyzing the Harvard Six Cities Study's air quality data have also established a specific influence of 45Dockery, DW; Pope, CA, III; Xu, X; et al. ( 1993) An association between air pollution and mortality in six U. S. cities. N Engl J Med 329: 1753 1759.

46Pope, CA, III; Thun, MJ; Namboordiri, MM; et al. ( 1995) Particulate air pollution as a predictor of mortality in a prospective study of U. S. adults. Am J Respir Crit Care Med 151: 669

674.

47Hoek, G; Brunekreef, B; Goldbohm, S; et al. ( 2002) Association between mortality and indicators of traffic related air pollution in the Netherlands: a cohort study. Lancet 360: 1203

1209. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 39 mobile source related PM2.5 on daily mortality48 and a concentration response function for mobile source associated PM2.5 and daily mortality. 49 c. What are current and projected levels of PM?

The NAAQS for PM2.5 were established by EPA in 1997 ( 62 Fed. Reg., 38651, July 18,

1997). The short term ( 24 hour) standard is set at a level of 65

g/ m3 based on the 98th percentile concentration averaged over three years. The long term standard specifies an expected annual arithmetic mean not to exceed 15 ug/ m3 averaged over three years.

Approximately XXX million people live in XXXX counties and XXX areas which EPA has recommended be designated nonattainment for the PM2.5 NAAQS. 50 [ Update soon after PM designations are made]. In addition, tens of millions of people live in areas where there is a significant future risk of failing to maintain or achieve the PM2.5 NAAQS.

48Laden F; Neas LM; Dockery DW; et al. ( 2000) Association of fine particulate matter from different sources with daily mortality in six U. S. cities. Environ Health Perspect 108( 10): 941 947.

49Schwartz J; Laden F; Zanobetti A. ( 2002) The concentration response relation between PM( 2.5) and daily deaths. Environ Health Perspect 110( 10): 1025 1029.

50A map that shows the current ozone, PM2.5, and federal Class I visibility areas and a list of affected counties can be found in Docket No. OAR 2002 0030. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 40 This is illustrated by the air quality modeling performed recently in connection with our CAIR rule, which suggests that elevated PM2.5 levels are likely to continue to exist in the future in many areas in the absence of additional emission controls. 51 For example in the eastern U. S.

in 2015, based on emission controls currently adopted, we project that 66 [ UPDATE WHEN CAIR COMES OUT] million people will live in 13 counties with average PM2.5 levels above 15 ug/ m3. [ UPDATE IF CAIR DOESN'T COME OUT]

While the final implementation process for bringing the nation's air into attainment with the PM2.5 NAAQS is still being completed in a separate rulemaking action, the basic framework is well defined by the statute. EPA's current plans call for designating PM2.5 nonattainment areas in late 2004. Following designation, section 172( b) of the Clean Air Act allows states up to three years to submit a revision to their state implementation plan ( SIP) that provides for the attainment of the PM2.5 standard. Based on this provision, states could submit these SIPs as late as the end of 2007. Section 172( a)( 2) of the Clean Air Act requires that these SIP revisions demonstrate that the nonattainment areas will attain the PM2.5 standard as expeditiously as practicable but no later than five years from the date that the area was designated nonattainment.

However, based on the severity of the air quality problem and the availability and feasibility of control measures, the Administrator may extend the attainment date " for a period of no greater than 10 years from the date of designation as nonattainment." Therefore, based on this information, we expect that most or all are as will need to attain the PM2.5 NAAQS in the 2009 to 2014 time frame, and then be required to maintain the NAAQS thereafter.

51[ CITE NEEDS TO BE UPDATED CAIR IS FINALIZED  expected soon] Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 41 Since the emission reductions expected from today's final rule will occur during the time period when areas will need to attain the standard under either option, these standards will assist States in their effort to meet the new PM2.5 NAAQS. Note: There is no basis for this statement.

Although there is scientific basis for the tie between NOx and PM  this discussion appears to try to equate NOx mitigation with PM mitigation. Measures taken to mitigate NOx in aircraft engines may, in fact, increase fuel burn, other gaseous emissions, and PM at the source ( engine exit plane). The tradeoffs and uncertainties must be recognized and acknowledged. Although the ne NOx standards may help mitigate PM  there are tradeoffs with the mitigation of PM inception that must be understood. C. Other Environmental Effects This section presents information on four categories of public welfare and environmental impacts related to NOx and fine PM emissions: acid deposition, eutrophication of water bodies,

plant damage from ozone, and visibility impairment. These environmental effects are described in detail in the Final Regulatory Analysis for our recent Clean Air Nonroad Diesel rule. 52 1. Acid Deposition 52U. S. EPA ( 1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,

EPA/ 600/ P 93/ 004aF. This document can be found in Docket No. A 99 06. Document Nos.

IIA 15 to 17. U. S. EPA ( 2004). Final Regulatory Assessment: Control of Pollution from Nonroad Diesel Engines, EPA420 R 04 007. This document can be found in Docket No. OAR 2002

0030, Document No. OAR 2002 0030 0128. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 42 Acid deposition, or acid rain as it is commonly known, occurs when NOx and SO2 react in the atmosphere with water, oxygen, and oxidants to form various acidic compounds that later fall to earth in the form of precipitation or dry deposition of acidic particles. 53 Acid rain contributes to damage of trees at high elevations and in extreme cases may cause lakes and streams to become so acidic that they cannot support aquatic life. In addition, acid deposition accelerates the decay of building materials and paints, including irreplaceable buildings, statues,

and sculptures that are part of our nation's cultural heritage. To reduce damage to automotive paint caused by acid rain and acidic dry deposition, some manufacturers use acid resistant paints,

at an average cost of $ 5 per vehicle for a total of $ 80 85 million per year when applied to all new cars and trucks sold in the U. S. each year.

The NOx reductions from today's action will help reduce acid rain and acid deposition,

thereby helping to reduce acidity levels in lakes and streams throughout the country and helping to accelerate the recovery of acidified lakes and streams and the revival of ecosystems adversely affected by acid deposition. Reduced acid deposition levels will also help reduce stress on forests, thereby accelerating reforestation efforts and improving timber production.

53Much of the information in this subsection was excerpted from the EPA document,

Human Health Benefits from Sulfate Reduction, written under Title IV of the 1990 Clean Air Act Amendments, U. S. EPA, Office of Air and Radiation, Acid Rain Division, Washington, DC 20460, November 1995. A copy of this document is available in Docket No. OAR 2002 0030,

Document No. OAR 2002 0030 0028. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 43 Deterioration of our historic buildings and monuments, and of buildings, vehicles, and other structures exposed to acid rain and dry acid deposition will be reduced, and the costs borne to prevent acid related damage may also decline.

2. Eutrophication and Nitrification In recent decades, human activities have greatly accelerated nutrient impacts, such as nitrogen and phosphorus, causing excessive growth of algae and leading to degraded water quality and associated impairment of fresh water and estuarine resources for human uses. 54 Eutrophication is the accelerated production of organic matter, particularly algae, in a water body. This increased growth can cause numerous adverse ecological effects and economic impacts, including nuisance algal blooms, dieback of underwater plants due to reduced light penetration, and toxic plankton blooms. Algal and plankton blooms can also reduce the level of dissolved oxygen, which can also adversely affect fish and shellfish populations.

Deposition of nitrogen from aircraft engines contributes to elevated nitrogen levels in waterbodies. The NOx reductions from today's promulgated standards will help reduce the airborne nitrogen deposition that contributes to eutrophication of watersheds, particularly in aquatic systems where atmospheric deposition of nitrogen represents a significant portion of total nitrogen loadings.

54Deposition of Air Pollutants to the Great Waters, Third Report to Congress, June 2000. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 44 3. Plant Damage from Ozone Ground level ozone can also cause adverse welfare or environmental effects. 55 Specifically, ozone enters the leaves of plants where it interferes with cellular metabolic processes. This interference can be manifest either as visible foliar injury from cell injury or death, and/ or as decreased plant growth and yield due to a reduced ability to produce food. With fewer resources, the plant reallocates existing resources away from root storage, growth and reproduction toward leaf repair and maintenance. Plants that are stressed in these ways become more susceptible to disease, insect attack, harsh weather and other environmental stresses.

Because not all plants are equally sensitive to ozone, ozone pollution can also exert a selective pressure that leads to changes in plant community composition.

As discussed earlier, aircraft engine emissions of NOx contribute to ozone. The final standards will aid in the reduction of ozone and, therefore, help reduce crop damage and stress from ozone on vegetation.

4. Visibility 55U. S. EPA ( 1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,

EPA/ 600/ P 93/ 004aF. Docket No. A 99 06. Document Nos. II A 15 to 17. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 45 Visibility can be defined as the degree to which the atmosphere is transparent to visible light. 56 Fine particles with significant light extinction efficiencies include organic matter,

sulfates, nitrates, elemental carbon ( soot), and soil.

Visibility is important because it directly affects people's enjoyment of daily activities in all parts of the country. Individuals value good visibility for the well being it provides them directly, both in where they live and work, and in places where they enjoy recreational opportunities. Visibility is also highly valued in significant natural areas such as national parks and wilderness areas, because of the special emphasis given to protecting these lands now and for future generations.

As discussed previously, aircraft engine emissions of NOx are precursors to PM2.5. In 1997, EPA established the secondary ( welfare based) PM2.5 NAAQS as equal to the primary ( health based) NAAQS of 15 ug/ m3 ( based on a 3 year average of the annual mean) and 65 56National Research Council, 1993. Protecting Visibility in National Parks and Wilderness Areas. National Academy of Sciences Committee on Haze in National Parks and Wilderness Areas. National Academy Press, Washington, DC. This book can be viewed on the National Academy Press Website at http:// www. nap. edu/ books/ 0309048443/ html/. See also U. S.

EPA Air Quality Criteria Document for Particulate Matter ( 2004). This document is available in Docket No. OAR 2002 0030, Document No. OAR 2002 0030 0129 and OAR 2002 0030 0130.

See also Review of the National Ambient Air Quality Standards for Particulate Matter: Policy Assessment of Scientific and Technical Information. These documents can be found in Docket A 99 06, Documents No. II A 23 and IV A 130 32. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 46 ug/ m3 ( based on a 3 year average of the 98th percentile of the 24 hour average value) ( 62 FR 38669, July 18, 1997). EPA concluded that PM2.5 causes adverse effects on visibility in various locations, depending on PM concentrations and factors such as chemical composition and average relative humidity. In 1997, EPA demonstrated that visibility impairment is an important effect on public welfare and that unacceptable visibility impairment is experienced throughout the U. S., in multi state regions, urban areas, and remote federal Class I areas. 57 Furthermore, in setting the PM2.5 NAAQS, EPA acknowledged that levels of fine particles below the NAAQS may also contribute to unacceptable visibility impairment and regional haze problems in some areas, and section 169 of the Act provides additional authorities to remedy existing impairment and prevent future impairment in the 156 national parks, forests and wilderness areas labeled as mandatory Federal Class I areas ( 62 FR 38680 81, July 18,

1997).

Taken together with other programs, reductions from this final rule will help to improve visibility across the nation, including mandatory Federal Class I areas.

III. Aircraft Engine Standards Under the authority of section 231 of the CAA, EPA today adopts standards equivalent to ICAO's February 1999 NOx emission standards ( these NOx standards were adopted at CAEP/ 4 in 57A map that shows the current ozone, PM2.5, and federal Class I visibility areas and a list of affected counties can be found in Docket No. OAR 2002 0030. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 47 1998 and approved by the ICAO Council in 1999) and March 1997 test procedure amendments.

Today's emission standards and test procedure amendments apply to commercial aircraft engines, and these standards do not apply to aircraft engines used only for general aviation or military applications. 58 ( General aviation and military aircraft can use commercial aircraft engines subject to these standards   e. g., small regional jet engines are also utilized in executive general aviation aircraft and larger commercial aircraft engines may also be used in military transport aircraft). The commercial aircraft engines subject to today's NOx standards are those gas turbine engines that are newly certified ( and newly designed) after the effective dates of the regulations. ( Newly manufactured engines of already certified models   i. e., those individual engines that are part of an already certified engine model, but are built after the effective date of the regulations for such engines and have never been in service   will not have to meet these standards). 59 The NOx emission standards and their effective dates are described below in this section, and the test procedure amendments are discussed later in section IV.

58In the proposal, we stated that no general aviation or military engines are covered by the proposal; however, this statement may need some clarification in today's final rulemaking. See the Section 5.2 of the Summary and Analysis of Comments of this rulemaking for further discussion of general aviation and military aircraft .

59This provision does not mean the re certification or retrofit of existing in use engines.

Instead the provision does not require the ongoing production of engines that have already been certified to meet the new standards. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 48 A. What Are The NOx Standards For Newly Certified Engines?

As discussed earlier in sections I and II of today's notice, section 231( a)( 2)( A) of the CAA authorizes EPA to establish emission standards for aircraft engine emissions "... which in his judgment causes, or contributes to, air pollution which may reasonably be anticipated to endanger public health or welfare." The Administrator may revise such standards from " time to time." CAA section 231( b) requires that any emission standards provide sufficient lead time " to permit the development and application of the requisite technology, giving appropriate consideration to the cost of compliance within such period."

Today's rule adopts near term standards that will go into effect [ Insert date 30 days after date of publication in the FEDERAL REGISTER] to ensure future engines do not jeopardize recent or past technology gains. These standards are equivalent to the CAEP/ 4 NOx international consensus emissions standards for aircraft engines adopted by ICAO's CAEP in 1998.60 This final rule to promulgate aircraft engine NOx standards equivalent to CAEP/ 4 standards is consistent with U. S. obligations under ICAO. By issuing standards that meet or exceed ICAO CAEP/ 4 standards, we satisfy these obligations. As indicated earlier in section I of today's rule, the implementation date, December 31, 2003, has already occurred for the CAEP/ 4 60ICAO, CAEP, Fourth Meeting, Montreal, Quebec, April 6 8, 1998, Report, Document 9720, CAEP/ 4. Copies of this document can be obtained from the ICAO website located at www. icao. int. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 49 standards, and we need to promulgate the standards in accordance with U. S. obligations under ICAO. At the same time, EPA anticipates establishing more stringent NOx standards in the future. In February 2004, CAEP/ 6 ( sixth meeting of CAEP) agreed to establish more stringent international consensus emission standards for aircraft engines. Such standards would likely be a central consideration in a future EPA regulation of aircraft engine emissions.

We believe this approach is the most appropriate means to address emissions from aircraft engines in this rulemaking. It codifies current practice, with no significant lead time, as a near term approach. 61 EPA has authority to revise emission standards from " time to time." EPA intends to address more stringent emission standards requiring more lead time in a future rulemaking ( see section III. A. 5 for further discussion of future standards), as the ICAO and CAEP process develops progressively more stringent standards.

1. Today's NOx Standards 61As described later, more information and greater lead time would be necessary to require more stringent standards. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 50 EPA is adopting standards equivalent to ICAO's 1999 NOx emission standards for newly certified aircraft gas turbine engines ( turbofan and turbojet engines) of rated thrust or output greater than 26.7 kilonewtons ( kN) with compliance dates as follows: 62 For engines of a type or model of which that date of manufacture of the first individual production model was after December 31, 2003 ( see below for further discussion on the effective date of these standards):

a) for engines with a pressure ratio of 30 or less:

i) for engines with a maximum rated output of more than 89.0 kN:

NOx = ( 19 + 1.6( rated pressure ratio)) g/ kN( rated output)

ii) for engines with a maximum rated output of more than 26.7 kN but not more than 89.0 kN:

NOx = ( 37.572 + 1.6( rated pressure ratio)  0.2087( rated output)) g/ kN( rated output)

b) for engines with a pressure ratio of more than 30 but less than 62.5:

i) for engines with a maximum rated output of more than 89.0 kN:

NOx = ( 7 + 2.0( rated pressure ratio)) g/ kN( rated output)

ii) for engines with a maximum rated output of more than 26.7 kN but not more than 89.0 kN:

62This includes standards for low, mid, and high thrust engines ( see below for further discussion of the different standards based on the thrust of the engines) . Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 51 NOx = ( 42.71 + 1.4286( rated pressure ratio)  0.4013( rated output) +

0.00642( rated pressure ratio  rated output)) g/ kN( rated output)

c) for engines with a pressure ratio of 62.5 or more:

NOx = ( 32 + 1.6( rated pressure ratio)) g/ kN( rated output).

The NOx emission standards presented above are equivalent to the ICAO NOx standards that have an implementation date of December 31, 2003.63 However, since this date has past, the NOx emission standards prescribed above for newly certified engines shall take effect as prescribed beginning [ Insert date 30 days after date of publication in the FEDERAL REGISTER].

2. NOx Standards for Newly Certified Mid and High Thrust Engines EPA is adopting NOx standards for newly certified mid and high thrust engines ( those engines designed and certified after the effective date of the regulations, which have a rated 63) ICAO's CAEP/ 4 NOx standards became effective July 19, 1999, and applicable as of November 4, 1999. December 31, 2003 is the implementation date for these standards.

However, for the purpose of this Notice the effective date is considered the implementation date.

( ICAO, " Aircraft Engine Emissions," International Standards and Recommended Practices,

Environmental Protection, Annex 16, Volume II, Second Edition, July 1993   Amendment 4,

July 19, 1999.) Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 52 output or thrust greater than 89 kN) that generally represent about a 16 percent reduction ( or increase in stringency) from the existing standard. ( See section III. A. 1( a)( i) and III. A. 1( b)( i)

above for the standards for mid and high thrust engines.) More specifically, at a rated pressure ratio of 30 the NOx standards represent a 16 percent reduction from the existing standard. At rated pressure ratios of 10 and 20 , the standards correspond to 27 and 20 percent reductions,

respectively. In addition, at rated pressure ratios of 40 and 50, the NOx standards signify 9 and 4 percent reductions, respectively. Also, today's and existing standards are equivalent at a rated pressure ratio of 62.5. See Figure III. B 1 in section III. B for a comparison of today's NOx standards ( equivalent to CAEP/ 4 standards) to the existing standards ( equivalent to CAEP/ 2 standards) .

3. NOx Standards for Newly Certified Low Thrust Engines For newly certified low thrust engines ( engines with a thrust or rated output of more than 26.7 kN but not more than 89.0 kN), EPA is adopting near term NOx standards that are equivalent to CAEP/ 4 standards for such engines, and these standards are different than today's standards for mid and high thrust engines ( engines with thrust greater than 89.0 kN).

In 64Today's NOx standards for low thrust or small engines specify that engines with a rated output or thrust at 26.7 kN meet the existing standard, and engines with a rated output at 89 kN meet today's ( or CAEP/ 4) standards. For engines with rated outputs or thrust levels between 26.7 and 89 kN, a linear interpolation was made between the low range of the existing standard Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 53 addition to rated pressure ratio, the standards for low thrust engines will also be dependent on an engine's thrust or rated output. 65 ( See section III. A. 1( a)( ii) and III. A. 1( b)( ii) for a description of these different standards.) For example, at a rated pressure ratio of 30 and a thrust of 58 kN ( thrust level in the middle of 26.7 kN and 89 kN), these standards are an 8 percent reduction ( or increase in stringency) from the existing standard compared to a 16 percent reduction for the standards for mid and high thrust engines. 66 and the high range of today's standard based upon the rated output to determine the NOx limits for such engines. Thus, thrust dependent standards are being adopted for engines with rated output or thrust between 26.7 kN and 89 kN.

65The standards for mid and high thrust engines are dependent only on an engine's rated pressure ratio.

66Additional examples of the standards for low thrust engines in comparison to the standards for mid and high thrust engines are provided below. At rated pressure ratios of 10 and 20 with a thrust of 58 kN, today's low thrust engine standards are a 14 and 10 percent reduction from the existing standard, respectively. Whereas, at these same rated pressure ratios,

today's standards for mid and high thrust engines are 27 and 20 percent reductions.

In addition, at rated pressure ratios of 40 and 50 with a thrust of 58 kN, these low thrust engine standards signify a 5 and 2 percent reduction from the existing standard, respectively. In comparison, at these same rated pressure ratios, today's standards for mid and high thrust engines are 9 and 4 percent reductions. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 54 The existing standards were not set at a stringency level that created a need for low thrust engines to have different requirements, but at the level of NOx stringency adopted today different requirements are considered necessary for such engines. Due to their physical size, it is difficult to apply the best NOx reduction technology to low thrust or small engines. The difficulty increases progressively as size is reduced ( from around 89 kN). 67 For example, the relatively small combustor space and section height of these engines creates constraints on the use of low NOx fuel staged combustor concepts which inherently require the availability of greater flow path cross sectional area than conventional combustors. 68 Also, fuel staged combustors need more fuel injectors, and this need is not compatible with the relatively lower total fuel flows of lower thrust engines. ( Reductions in fuel flow per nozzle are difficult to attain without having clogging problems due to the small sizes of the fuel metering ports.) In addition, lower thrust engine combustors have an inherently greater liner surface to combustion volume ratio, and this requires increased wall cooling air flow. Thus, less air will be available to obtain acceptable 67ICAO/ CAEP, Report of Third Meeting, Montreal, Quebec, December 5 15, 1995,

Document 9675, CAEP/ 3.

68" The burner section of an aircraft engine, which contains the combustion chamber,

burns a mixture of fuel and air, and delivers the resulting gases to the turbine at a temperature which will not exceed the allowable limit at the turbine inlet." ( United Technologies Pratt and Whitney, " The Aircraft Gas Turbine Engine and Its Operation," August 1998.) Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 55 turbine inlet temperature distribution and for emissions control. 69 Since the difficulties increase progressively as engine thrust size is reduced, EPA believes it is appropriate to make a graded change in stringency of today's NOx standards for low thrust engines.

4. Rationale for Today's NOx Standards for Newly Certified Low, Mid, and High Thrust Engines Today's standards for low, mid, and high thrust engines, which are equivalent to the CAEP/ 4 standards, ensure that new engine designs will incorporate the existing combustor technology and will not perform worse than today's current engines. This final rule to promulgate aircraft engine NOx standards equivalent to CAEP/ 4 standards is consistent with U. S.

obligations under ICAO. By issuing standards that meet or exceed the minimum stringency levels of ICAO CAEP/ 4 standards, we satisfy these obligations. ( See section I. B for a discussion of the obligation of ICAO's participating nations). As indicated earlier, the implementation date,

December 31, 2003, has already occurred for the CAEP/ 4 standards, and we need to promulgate the standards to meet our obligations for the CAEP/ 4 standards. Moreover, since we have already gone past the implementation date of the ICAO/ CAEP/ 4 standards, there is not sufficient lead time to require more stringent emission standards in the very near term. As discussed later 69ICAO/ CAEP Working Group 3 ( Emissions), " Combined Report of the Certification and Technology Subgroups," section <IP_ADDRESS>, Presented by the Chairman of the Technology Subgroup, Third Meeting, Bonn, Germany, June 1995. A copy of this paper can be found in Docket OAR 2002 0030. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 56 in section III. A. 5 for future standards, we plan to address whether to take action on more stringent NOx standards in the future because pursuant to section 231( b) of the CAA we need more time to better understand the cost of compliance with such standards ( see section III. A. 5 for further discussion regarding lead time). Also, see the Summary and Analysis of Comments for this rulemaking for further discussion of this near term approach.

EPA believes that today's standards will not impose any additional burden on manufacturers, because manufacturers are already designing new engines to meet the ICAO international consensus standards by 2004 ( see section VIII of today's action for further discussion of regulatory impact). Even though the U. S. did not immediately adopt the ICAO NOx standards after 1999, engine manufacturers have continued to make progress in reducing these emissions. Today's standards are aimed at assuring that this progress is not reversed in the future.

We received a number of comments from state and local governments and environmental groups stating that the NOx standards should be technology forcing standards ( a performance level that is beyond what sources are currently achieving). They stated that the standards are not technology forcing since 94 percent of all engine models currently in production already meet the standards ( 85 percent did in 1999 when the ICAO adopted the standards). Also, state and local governments and environmental groups stated that since the standards are not technologyforcing and most engines already meet the standards, aircraft engine NOx will increase. They expressed concern the many states are facing air quality challenges with implementation of the new 8 hour ozone standard and fine particulate matter ( PM2.5) Note: Again, although there is scientific basis for the tie in between NOx and PM  this discussion appears to try to equate NOx Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 57 mitigation with PM mitigation. Measures taken to mitigate NOx in aircraft engines may, in fact,

increase fuel burn, other gaseous emissions, and PM at the source. There are no certification requirements to measure PM from aircraft engines  hence there is a very limited database to help assess tradeoffs and base mitigation actions. Furthermore, we do not even yet have reliable techniques to measure aircraft PM. These tradeoffs and uncertainties must be recognized and acknowledged. This discussion must acknowledge that though new NOx standards may help mitigate PM  efforts to mitigate NOx may also increase PM and we must carefully examine the impact and cost/ benefits to optimize environmental benefits. national ambient air quality standards ( NAAQS). Decreases in ozone and PM2.5 precursors, including NOx, requires controls of emissions from all sectors, in addition to controls already implemented for 1 hour ozone NAAQS. For nonattainment areas, aircraft emissions are problematic, and the standards will not reduce aircraft emissions or address aircraft NOx pollution.

Engine and airframe manufacturers and airlines supported the standards and opposed the concept of technology forcing standards. Airlines indicated that the rulemaking would codify aircraft emission standards determined to be technologically feasible. In addition, airlines expressed that technology forcing standards would be contrary to the CAA. Aircraft engine emission standards adopted according section 231 of the CAA must be based on what is technologically feasible, and the standards cannot be amended if the change would significantly increase noise or adversely affect safety. They suggested that a technology forcing NOx standard could adversely affect noise and safety. In addition, they indicated that section 231 of the Act is different from other sections of the CAA that call for technology forcing standards. Air carriers expressed that section 231 requires that standards already be technologically feasible and not Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 58 compromise noise and safety. In addition, airlines expressed that whether a " standard is technologically feasible depends not just on whether it can be achieved in a laboratory setting,

but whether it can be achieved on a range of actual aircraft engine and airframe combinations that are certified as airworthy, safe, and fully operable under flight conditions. Moreover, such demonstrated technology must be available for application over a sufficient range of newly certificated aircraft, not just on a few airframe/ engine combinations." ( See the Summary and Analysis of Comments of this rulemaking for further discussion of comments.)

In response to these comments, we refer to Section 231( b) of the CAA, which requires that any emission standards " take effect after such period as the Administrator finds necessary ( after consultation with the Secretary of Transportation) to permit the development and application of the requisite technology, giving appropriate consideration to the cost of compliance within such period." This statutory language is forward looking and on its face assumes that the requisite technology to meet emission standards might not currently be in widespread production. Section 231( b) thus allows EPA to establish aircraft emission standards at a level that is currently not achieved in practice by all aircraft engines ( i. e., the standards would force some technological improvements), provided there is sufficient lead time before such standards become effective, the agency gives appropriate consideration to the cost of compliance within the provided lead time, consults with the Secretary of Transportation, and takes into account considerations of safety and noise. EPA also needs to have a technical basis for expecting the standards will be achievable in a specific period of time. While the statutory language of section 231 is not identical to other provisions in title II of the CAA that direct EPA to establish technology based standards for various types of engines, EPA interprets its authority Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 59 under section 231 to be somewhat similar to those provisions that require us to identify a reasonable balance of specified emissions reduction, cost, safety, noise, and other factors. See,

e. g., Husqvarna AB v. EPA, 254 F. 3d 195 ( D. C. Cir. 2001) ( upholding EPA's promulgation of technology based standards for small non road engines under section 213( a)( 3) of the CAA).

However, we are not compelled under section 231 to obtain the " greatest degree of emission reduction achievable" as per sections 213 and 202 of the CAA, and so EPA does not interpret the Act as requiring the agency to give subordinate status to factors such as cost, safety, and noise in determining what standards are reasonable for aircraft engines. Rather, EPA has greater flexibility under section 231 in determining what standard is most reasonable for aircraft engines,

and is not required to achieve a " technology forcing" result. The fact the most engines already meet standards would not in itself mean that the standard is inappropriate, provided the agency has a reasonable basis after considering all the relevant factors for setting the standard ( with an appropriate period of lead time for that standard) at a level that results in no actual emissions reduction from the baseline.

By the same token, EPA does not agree that a technology forcing standard would be precluded by section 231, in light of section 231( b)' s forward looking language. Nor would EPA have to demonstrate that a technology is currently available universally or over a broad range of aircraft in order to base a standard on the emissions performance of such technology   the agency is not limited in identifying what is " technologically feasible" as what is already technologically achieved. However, EPA would, after consultation with DOT, need to provide manufacturers sufficient lead time to develop and implement requisite technology that can be certified by the FAA as airworthy for any class of engine it would be applicable to. As section Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 60 231 conveys, there is an added emphasis on the consideration of safety ( see, e. g., sections 231( a)( 2)( B)( ii) (" The Administrator shall not change the aircraft engine emission standards if such change would [. . .] adversely affect safety") and 231( c) (" Any regulations in effect under this section [. . .] shall not apply if disapproved by the President, after notice and opportunity for public hearing, on the basis of a finding by the Secretary of Transportation that any such regulation would create a hazard to aircraft safety"). Therefore, it is reasonable for EPA to give greater weight to considerations of safety in this context than it might in balancing emissions reduction, cost, and energy factors under other title II provisions.

EPA is aware that many states face air quality challenges in light of the new ozone and PM2.5 NAAQS, and since section 233 of the CAA vests authority only in EPA to set aircraft emission standards, we understand their perspective regarding the importance of setting more stringent NOx standards in the future. For these future standards, we expect to adopt standards developed through the CAEP process in ICAO. Further, we plan, working with FAA and NASA and other relevant agencies through the environmental Integrated Product Team for the Next Generation Air Transportation System ( NGATS), to conduct a review of technology for aircraft engines and the resulting trend in aircraft emissions as well as interrelationships with noise ( e. g,

standards effect on projected aircraft emissions growth and expected effects on noise). See section III. A. 5 below for further discussion of future NOx standards. ( See the Summary and Analysis of Comments of this rulemaking for further discussion of our responses to comments.)

5. Future NOx Standards for Newly Certified Low, Mid, and High Thrust Engines Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 61 More stringent standards for low, mid, and high thrust engines will likely be necessary and appropriate in the future. As discussed earlier in section II, the growth in aircraft emissions is projected to occur at a time when other mobile source categories are reducing emissions. 70 70The projected growth in aircraft emissions is not simply from the number of operations,

but it could also be attributed to the change in the types of aircraft being operated. For example,

regional aircraft activity is growing ( regional aircraft are generally referred to as those aircraft with more than 19 but fewer than 100 seats   regional jets and turboprops). In the U. S., traffic flown by regional airlines increased about 20 percent in 1999 and is expected to grow approximately 7 percent annually during the next ten years, compared to 4 to 6 percent for the major airlines. In addition, regional jets comprised about 25 percent of the regional aircraft fleet in 2000, up from only 4.2 percent in 1996, and their fraction of the fleet is expected to increase to nearly 50 percent by 2011. Regional aircraft are 40 to 60 percent less fuel efficient compare to larger narrow and wide body aircraft, and regional jets are 10 to 60 percent less fuel efficient than turboprop aircraft. Note: The units or basis for " fuel efficiency" needs to be specified for this statement to be unambiguous e. g., per passenger mile. EPA needs to also consider that engines that power regional jet aircraft produce much less NOx.. However, fuel costs have less of an effect on the operating costs of regional aircraft compared to large aircraft. In addition,

regional jets have historically operated at higher load factors than turboprops due to their popularity with travelers. ( R. Babikian, S. P. Lukachko and I. A. Waitz, " Historical Fuel Efficiency Characteristics of Regional Aircraft from Technological, Operational, and Cost Perspectives," Journal of Air Transport Management, Volume 8, No. 6, pp. 389 400, Nov. 2002. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 62 The 1999 EPA study of commercial aircraft activity in ten cities projected that the aircraft NOx emissions would double in some of these cities by 2010, and the aircraft component of the regional mobile source NOx emissions in the ten cities would grow from a range of 1 to 4 percent that existed in 1990 to a range of 2 to 10 percent in 2010.71 ( As indicated earlier, the above projections were made prior to the tragic events of September 11, 2001, and the economic downturn. A January 2003 report by the Department of Transportation indicated that the combination of the September 11, 2001 terrorist attacks and a cut back in business travel had a significant and perhaps long lasting effect on air traffic demand. While the FAA expects the demand for air travel to recover, and then continue a long term trend of annual growth in the United States, it will grow at a lower rate and from a lower base than originally forecast.. More recently, as discussed earlier, FAA reports that flights ( or activity) of commercial air carriers will increase by 22 percent from 2000 to 2015, about 1/ 3 less than what was forecast before September 11th. While flight activity, and thus NOx emissions, will be lower than originally anticipated, the relative size of the contribution of aircraft to national NOx levels may increase due to the potential decreased contribution from other mobile sources; hence, further action may be necessary in the future to reduce aircraft NOx emissions in nonattainment areas.

Further stringency of the NOx standards would reduce the expected growth in commercial aircraft NOx emissions. The importance of controlling aircraft emissions has grown in many 71U. S. EPA, " Evaluation of Air Pollutant Emissions from Subsonic Commercial Jet Aircraft," April 1999, EPA420 R 99 013. This study is available at http:// www. epa. gov/ otaq/ aviation. htm. It can also be found in Docket No. OAR 2002 0030. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 63 areas ( especially areas not meeting the 1 hour and 8 hour ozone NAAQS) as controls on other sources become more stringent and attainment of the NAAQS's has still not been achieved.

( Many airports in the U. S. are located in nonattainment areas. 73) As activity increases, aircraft would emit increasing amounts of NOx in many nonattainment areas, and thus, aircraft NOx emissions would further aggravate the problems in these areas ( either by emitting pollutants directly within a nonattainment area or by contributing to regional transport emissions in an area upwind of a nonattainment area). More stringent aircraft engine NOx standards may assist in alleviating these problems in nonattainment areas, and they may aid in preventing future concerns in areas currently designated as attainment ( or maintenance) areas. In addition,

attainment or maintenance of the NAAQS may depend upon aircraft engines being subject to a program of control compatible with their significance as pollution sources. ( See the Summary and Analysis of Comments for this rulemaking for further discussion of future standards and the environmental need for control.)

EPA, therefore, is considering the exploration of more stringent future standards, beyond today's standards. The ICAO Council last year adopted more stringent international consensus 73For information on the geographic location of airports, see the following U. S.

Department of Transportation ( Bureau of Transportation Statistics) website: www. bts. gov/ oai.

The report or database provided on the website entitled, " Airport Activity Statistics of Certificated Air Carriers: Summary Tables 2000," lists airports by community. In addition, see the following EPA website for information on nonattainment areas for criteria pollutants:

www. epa. gov/ oar/ oaqps/ greenbk. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 64 NOx emission standards for newly certified aircraft engines ( implementation date of after December 31, 2007). The CAEP/ 6 NOx standards generally represent about a 12 percent increase in stringency from the standards promulgated in this final rule ( or the CAEP/ 4 NOx standards). 74 ( These standards were accompanied by more stringent standards for low thrust engines). Moreover, CAEP agreed to review the stringency of the NOx standards again durint the work program for the eighth meeting of CAEP, which will commence in early 2007 and is expected to culminate in early 2010. Such standards will be a central consideration in a future EPA regulation of aircraft engine emissions. Thus it will be important that the EPA and FAA continue to actively participate in the technical emissions work activity that will endeavor to establish the technological basis for any increase in stringency that CAEP will contemplate. We believe this ongoing phased approach is the most appropriate means to address emissions from aircraft engines.

As we discussed in the proposal, activity is also underway in CAEP to identify and assess the potential for long term technology goals to be established for further emission reductions,

74ICAO, CAEP, Sixth Meeting, Montreal, Quebec, February 2 12, 2004, Report, Letter of Transmittal to the President of Council From the Chairman of the Sixth Meeting of CAEP,

CAEP/ 6 WP/ 57 ( Report o Agenda Item 1). Copies of this document can be obtained from ICAO ( www. icao. int). It can also be found in Docket No. OAR 2002 0030. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 65 including implementing a CAEP approved process to set and review these goals. 75,76 The aim of the goal setting activity is to complement the ICAO CAEP standard setting process with 75ICAO, CAEP, Sixth Meeting, Montreal, Quebec, February 2 12, 2004, Report, Letter of Transmittal to the President of Council From the Chairman of the Sixth Meeting of CAEP,

CAEP/ 6 WP/ 57 ( Report on Agenda Item 4). Copies of this document can be obtained from ICAO ( www. icao. int). It can also be found in Docket No. OAR 2002 0030.

76For the purposes of setting long term technology goals for aircraft emission reductions,

the CAEP/ 6 ( occurred in February 2004) future work program included the following items:

( a) implement a CAEP approved process to set, periodically review and update technology goals and identify environmental benefits, taking into account progress in ongoing research and development efforts toward reducing aircraft emissions, environmental interdependencies and trade offs, and scientific understanding of the effects of aircraft engine emissions;

( b) support and monitor development and methods for understanding the inter relationship of technology goals targeting individual emissions performance improvements; and ( c) develop the inputs appropriate for use of air quality and climate impact models to be used by CAEP to quantify the value of emissions reduction and to estimate the benefit from long term goals.

( ICAO, CAEP, Sixth Meeting, Montreal, Quebec, February 2 12, 2004, Report, Letter of Transmittal to the President of Council From the Chairman of the Sixth Meeting of CAEP,

CAEP/ 6 WP/ 57 ( Appendix A to the Report on Agenda Item 4  Revised Work Program for Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 66 information to aid the engine and airframe manufacturer's design process. The goals are expected to take into account the results of recently completed emissions reduction technology programs such as those conducted by National Aeronautics and Space Administration ( NASA)

and the European Commission and the timeline necessary to carry those technologies from the research phase through commercialization. 77 We support this CAEP work item for establishing long term goals. However, this should not be interpreted as agreement on our part that the CAEP process is the exclusive appropriate process for setting aircraft emissions reduction goals for encouraging the development of better performing technology. For example, the Next Generation Air Transportation System ( NGATS) plan released in December 2004 a Congressionally chartered and Administration endorse activity to develop research and plans to transform the air transportation system. Efforts there will include assessment of various technological and operational procedures to reduce aircraft emissions, including NOx, as well as a thorough assessment of interrelationships between noise and emissions and amongst emissions to enable maximizing environmental benefit derived from mitigating actions. Further, in EPA's long history of mobile source regulation, we have found that technology standards have been successfully used to stimulate technological development resulting in cleaner, cost effective, and CAEP, page 4A 7). Copies of this document can be obtained from ICAO ( www. icao. int). It can also be found in Docket No. OAR 2002 0030.

77ICAO, CAEP, Fourth Meeting, Montreal, Quebec, April 6 8, 1998, Report, Document 9720, CAEP/ 4, see Appendix A to the Report on Agenda Item 4 ( page 4 A 1). Copies of this document can be obtained from ICAO ( www. icao. int). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 67 safe engines. Note: Does this statement just apply to surface transportation, or all forms of transportation?

Manufacturers should be able to achieve additional reductions with more lead time than is provided by today's action. As we discussed in the proposal, in the future we intend to assess,

in cooperation with the NGATS Environmental Integrated Product Team ( IPT) whether or not the new international consensus and longer term standards, CAEP/ 6 NOx standards, would be stringent enough to protect the U. S. public health and welfare. If so, we would plan to propose to adopt the CAEP/ 6 NOx standards. EPA in consultation with DOT retains the discretion to adopt more stringent NOx standards in the future if the international consensus standards ultimately prove insufficient to protect U. S. air quality. As discussed earlier, the implementation date, December 31, 2003, has already occurred for the CAEP/ 4 standards, and we need to promulgate today's standards to meet our obligations for the CAEP/ 4 standards. This final rule to promulgate aircraft engine NOx standards equivalent to CAEP/ 4 standards is consistent with U. S. obligations under ICAO. We would not be able to quickly adopt a more stringent standard. However, we intend to consider further stringency in a future rulemaking. In addition, we have not yet assessed the costs ( and emission benefits) of more stringent standards,

but we anticipate doing so in the future for such standards. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 68 Consideration of more stringent NOx standards in the future will allow us to obtain important additional information on the costs of such standards. 78 As described earlier, section 231 of the CAA authorizes EPA from " time to time" to revisit emission standards, and it requires that any standards' effective dates permit the development of necessary technology, giving appropriate consideration to the cost. We did not propose more stringent NOx standards primarily because we needed more time to better understand the cost of compliance of such standards. Cost data is now available from CAEP/ 6 ( meeting occurred in February 2004), but we need to first adopt the standards equivalent to CAEP/ 4 today since we have already gone past the CAEP/ 4 implementation date. Although, as we described earlier, the CAEP/ 6 NOx standards will be a central consideration in a future aircraft engine emission standards, other levels of further stringency would also be under consideration, and additional cost information for such standards would need to be evaluated.

As we discussed in the proposal, producing ( and/ or developing) new engines or engine technologies require significant financial investments from engine manufacturers, which takes time to recoup ( the amount of time depends upon sales of engines, replacement parts, etc.). After evaluating additional cost information for future standards as well as other emissions reduction approaches, we would then be better situated to make decisions on an appropriate level of stringency and implementation timing that maximizes NOx reductions from aircraft engines,

78For low thrust engines, deferring regulatory action on more stringent future standards until after CAEP/ 6 would also enable us to obtain additional information on the technological feasibility of such standards. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 69 taking into consideration cost, safety, and the impact on fuel burn, other emissions and noise..

B. Newly Manufactured Engines of Already Certified Models We requested comment on whether the NOx standards would apply to newly manufactured engines of already certified models ( i. e., those individual engines that are part of an already certified engine model, but are built after the effective date of the regulations for such engines and have never been in service), 79 but after careful consideration and reviewing comments from stakeholders, we have decided not to include such engines in today's final rulemaking. It is important to mention that CAEP/ 6 did not adopt provisions to apply the CAEP/ 4 NOx standards to newly manufactured engines of already certified models ( a production cut off). CAEP/ 6 noted the industry view that market forces are the primary drivers of the development and incorporation of new technology ( asserting voluntary compliance would suffice), and an understanding at CAEP/ 4 that a production cut off would not be introduced in the future. CAEP/ 6, after reviewing that commitment, decided that "  this should not be 79This provision does not mean the re certification or retrofit of existing in use engines.

Instead the provision would require the ongoing production of engines that have already been certified to meet the new standards, rather than following CAEP/ 4 and merely applying today's standards to future engine designs and allowing currently produced engine models to meet the previous standards. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 70 interpreted as meaning that production cut offs would not be introduced in the future if the situation so warranted." 80,81 ( As we discussed in the proposal, CAEP's Forecasting and Economic Analysis Support Group ( FESG) further analyzed applying CAEP/ 4 NOx standards to newly manufactured engines of already certified models for CAEP/ 6, and assessed effective dates of 2, 4, and 6 years after December 31, 2003, which is the implementation date for newly certified engines. 82 FESG estimated that the cost per ton of NOx reduced would range from 80ICAO, CAEP, Sixth Meeting, Montreal, Quebec, February 2 12, 2004, Report, Letter of Transmittal to the President of Council From the Chairman of the Sixth Meeting of CAEP,

CAEP/ 6 WP/ 57 ( Report o Agenda Item 1).

81CAEP/ 6 noted that industry " pointed out that introduction of a production cut off now would cause the manufacturer to modify engines to meet the CAEP/ 4 standards, whereas if no cut off were imposed it was likely that they could be modified to meet the new standards agreed at this meeting." ( ICAO, CAEP, Sixth Meeting, Montreal, Quebec, February 2 12, 2004, Report,

Letter of Transmittal to the President of Council From the Chairman of the Sixth Meeting of CAEP, CAEP/ 6 WP/ 57, Report o Agenda Item 1, page 1 13.)

82ICAO, CAEP/ 6, Information Paper 28  Appendix B, " FESG Economic Assessment of Applying a Production Cut off to the CAEP/ 4 NOx Standard" Presented by the FESG Rapporteur, January 29, 2004 ( Same as CAEP SG20031 IP/ 9, which was presented at June 10,

2003 CAEP Steering Group Meeting). A copy of this document can be found in Docket No.

OAR 2002 30. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 71 $ 3,800 to $ 11,200 for the three effective dates. 83 The emission benefits and costs of this provision are discussed further below.)

1. What is the Status of Engines?

According to the ICAO Aircraft Engine Exhaust Emissions Data Bank84, nearly all already certified engine models ( 95 percent of already certified and in production engine models in the Data Bank) currently meet or perform better than the standards we are adopting today.

83ICAO, CAEP/ 6, Information Paper 28  Appendix B, " FESG Economic Assessment of Applying a Production Cut off to the CAEP/ 4 NOx Standard" Presented by the FESG Rapporteur, January 29, 2004 ( Same as CAEP SG20031 IP/ 9, which was presented at June 10,

2003 CAEP Steering Group Meeting). A copy of this document can be found in Docket No.

OAR 2002 30.

84 International Civil Aviation Organization ( ICAO), Aircraft Engine Exhaust Emissions Data Bank, July 26, 2004. This data bank is available at http:// www. caa. co. uk/ srg/ environmental/ emissions/ default. asp. In addition, a copy of a table including data of engine NOx emissions from the ICAO data bank and their margin to today's NOx standards can be found in Docket OAR 2002 0030.

85Based on the ICAO Data Bank, 151 out of 159 ( 95 percent) engine models that are currently in production perform better than the CAEP/ 4 NOx standards. The 8 engine models Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 72 ( See Figure III. B 1 below for a comparison of the NOx emission levels of current in production engines to the CAEP/ 4 NOx standards.

) At the time the CAEP/ 4 NOx standards were adopted in ( which are mid and high thrust engines) that are not achieving the CAEP/ 4 NOx standards are from three different Pratt and Whitney ( PW) engine types or families ( engines and their thrust variants with the same build standard). These engines are the following: ( 1) JT8D 217C E kit and JT8D 219 E kit; ( 2) PW4077D, PW4084D, and PW4090; and ( 3) PW4164, PW4168, and PW4168A. ( See Figure III. B 1 below that specifically shows these 8 in production models in relation to the CAEP/ 4 or proposed NOx standards.) For the year 2000, these 8 engine models were found on approximately 751 out of 20,137 ( 3.7 percent) aircraft owned by U. S. carriers and accounted for approximately 1,541,172 out of 11,505,063 ( 13.4 percent) of U. S. domestic flights.

( The above reference for the fleet fraction is BACK Aviation Solutions,

www. backaviation. com/ Information_ Services/ default. htm..

The domestic flight information is based on SAGE, the System for Assessing Aviation Emissions. SAGE is an FAA model that estimates aircraft emissions through the full flight profile using non proprietary input data, such as BACK, FAA's Enhanced Traffic Management System ( ETMS), and the Official Airline Guide ( OAG). The year 2000 air traffic movements database portion of SAGE was used to estimate the number of flights using the subject engines.)

86 For Figure III. B 1, the Allison, Pratt and Whitney ( does not include JT8D 217C E kit and JT8D 219 E kit), Rolls Royce, and Textron Lycoming engines with rated pressure ratios less than or equal to 20 and NOx levels above the CAEP/ 4 NOx standards actually perform better than Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 73 1998, all but 11 in production engines and 5 newly designed engine models ( these 5 engines were in the design and development process in 1998) had NOx emission levels that would perform better than the CAEP/ 4 standards.

Today, nearly all of the engines that did not meet the CAEP/ 4 NOx standard in 1998 now comply, except for the JT8D 200 engine family. 88 The other engine models have either, through additional testing or modifications, been improved to meet the standards or the engines are no longer in production. Although, as described earlier, the the standards, since there are different CAEP/ 4 NOx standards for these low thrust engines ( see section III. A. 3 for further discussion of NOx standards for low thrust engines). ( 47 of the 159 engines, 30 percent of engine models in production, in Figure IV. B 1 and the ICAO Aircraft Engine Exhaust Emissions Data Bank are low   thrust engines   engines with thrust greater than 26.7 kN but not more than 89 kN.)

87 ICAO, CAEP/ 4, Working Paper 4, " Economic Assessment of the EPG NOx Stringency Proposal," March 12, 1998, Presented by the Chairman of Forecasting and Economic Analysis Support Group ( FESG), Agenda Item 1: Review of proposals relating to NOx emissions,

including the amendment of Annex 16, Volume II, See Table 3.1 of paper. A copy of this paper can be found in Docket OAR 2002 0030.

88ICAO, CAEP/ 6, Working Paper 34, " NOx Production Cut off Consideration,"

Presented by the International Coordinating Council of Aerospace Industries Associations ( ICCAIA), January 6, 2004. A copy of this document can be found in Docket No. OAR 2002

30. Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 74 ICAO Data Bank shows that eight engine models or three different Pratt and Whitney engine types or families do not meet the NOx standards, we now know that except for the JT8D 217 and JT8D 219, six of the engine models or two of the engine types are compliant.

The PW4090 family of engines ( PW4077D, PW4084D, and PW4090) now has the means to eventually meet the standards utilizing technology that would meet the lower ranges of stringency options for the NOx standards considered at CAEP/ 6, although the manufacturer has projected it would be some years before it expects to meet CAEP/ 6 levels ( the manufacturer has not provided us with a projected necessary lead time to meet CAEP/ 4). The engine family that includes the PW4164, PW4168 and PW4168A engines is now certified with the PW 4168 Technologically Affordable Low NOx ( Talon) II engine combustor technology, which performs significantly better than the CAEP/ 4 standards. Also, the JT8D 200 engine powers the MD 80 aircraft, which is no longer in production. Yet, the JT8D 200 engine ( JT8D 217C and JT8D 219 in production engines) could potentially apply to future supersonic business jets. As stated in the proposal, the resulting NOx emission benefits of applying the standards to the JT8D 200 ( for these possible supersonic business jets) would be expected to be very small, and the costs would also likely be relatively small on an industry wide basis, although as discussed further below we do not feel we have a sufficient record at this point   nor have we presented it for public comment   to state our definitive views on these issues. However, the direct ( development)

costs would most likely be borne by one engine manufacturer. 89 As discussed in the proposal,

89ICAO, CAEP/ 6, Information Paper 28  Appendix B, " FESG Economic Assessment of Applying a Production Cut off to the CAEP/ 4 NOx Standard" Presented by the FESG Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 75 there is only one remaining newly designed engine model   out of the five identified in 1998   that would be certified after 2003, and it also has been made compliant with today's or CAEP/ 4 NOx standards. 90 In addition, as we indicated in the proposal, if an already certified engine design meets the standards that we are adopting today, then it is unlikely that either existing or future engine designs built to that design or type ( derivatives or thrust variants with the same build standard)

would not meet these standards. However, we may have been imprecise by stating in the proposal that when design modifications are made to an existing engine type, then this engine type would likely need to be recertified. Derivative versions of engines are not typically required to meet new standards for newly certified ( and newly designed) engines, but they usually need to Rapporteur, January 29, 2004 ( Same as CAEP SG20031 IP/ 9, which was presented at June 10,

2003 CAEP Steering Group Meeting). A copy of this document can be found in Docket No.

OAR 2002 30.

90 The PW Canada growth engines are the one remaining type of newly designed engines.

The ICAO Aircraft Engine Exhaust Emissions Data Bank currently does not have emissions certification data for such an engine, but Working Paper 34 presented at CAEP/ 6 indicated it would be compliant. ( ICAO, CAEP/ 6, Working Paper 34, " NOx Production Cut off Consideration," Presented by the International Coordinating Council of Aerospace Industries Associations ( ICCAIA), January 6, 2004. A copy of this document can be found in Docket No.

OAR 2002 30.) Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 76 comply with the same standards as were applied to the original engine model. 91,92 Thus,

derivative versions of engines typically do not need to be recertified. However, an engine type that does need to recertified will be required to comply with the CAEP/ 4 and today's NOx standards.

91ICAO, CAEP/ 4, Information Paper 3, " Clarification of the Definition of Derivative Version," Agenda Item 4  Future Work, Presented by United States, April 3, 1998. A copy of this document can be found in Docket No. OAR 2002 30.

92Chapter 1 of Part I of the ICAO Annex 16, Volume II, Aircraft Engine Emissions,

defines derivative version as follows: " an aircraft gas turbine engine of the same generic family as an originally type certificated engine and having features which retain the basic core engine and combustor design of the original model and for which other factors, as judged by the certificating authority, have not changed."

ICAO, " Aircraft Engine Emissions," International Standards and Recommended Practices, Environmental Protection, Annex 16, Volume II, Second Edition, July 1993 ( Chapter 1, Part I, Definitions and Symbols). Copies of this document can be obtained from ICAO ( www. icao. int). Preliminary Draft   Do not Cite, Quote, or Distribute 1/ 13/ 05 77 a 119 out of 159 ( 75 percent) of the in production engines have greater than 10 percent margin to the proposed ( or CAEP/ 4) NOx standards. 78 ( 49 percent) of the engines have more than 20 percent margin. 24 ( 15 percent) of the engines have greater than 30 percent margin. ( 120 of 159 ( 75 percent) of the in production engines have margin to the CAEP/ 6 NOx standards, which generally represent about a 12 percent increase in stringency from today's standards.)