E8-6148. Airworthiness Standards; Aircraft Engine Standards Overtorque Limits

AGENCY:

Federal Aviation Administration (FAA) DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to amend the certification standards for aircraft engines to introduce requirements for approval of maximum engine overtorque. This action would add a new engine overtorque test, amend engine ratings and operating limitations, and define maximum engine overtorque for certain turbopropeller and turboshaft engines. The proposed rule is intended to harmonize applicable U.S. and European standards and simplify airworthiness approvals for import and export of aircraft engines.

DATES:

Send your comments on or before June 24, 2008.

ADDRESSES:

You may send comments identified by Docket Number FAA-2007-28502 using any of the following methods:

• Federal eRulemaking Portal: Go to: http://www.regulations.gov and follow the online instructions for sending your comments electronically.
• Mail: Send comments to Docket Operations, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.
• Hand Delivery or Courier: Bring comments to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
• Fax: Fax comments to the Docket Operations at 202-493-2251.

For more information on the rulemaking process, see the SUPPLEMENTARY INFORMATION section of this document.

Privacy: We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. Using the search function of our docket web site, anyone can find and read the electronic form of all comments received into any of our dockets, including the name of the individual sending the comment (or signing the comment for an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://DocketsInfo.dot.gov.

Docket: To read background documents or comments received, go to: http://www.regulations.gov at any time and follow the online instructions for accessing the docket; or, go to the Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

For technical questions concerning this proposed rule contact Tim Mouzakis, Engine and Propeller Directorate, Standards Staff, ANE-110, Federal Aviation Administration (FAA), New England Region, 12 New England Executive Park, Burlington, Massachusetts 01803; telephone [phone]; facsimile [phone]; electronic mail “[e-mail]”. For legal questions concerning this proposed rule contact Vincent Bennett, Federal Aviation Administration, Office of Regional Counsel (ANE-7), New England Region, 12 New England Executive Park, Room 311, Burlington, MA 01803; telephone [phone]; facsimile [phone]; electronic mail [e-mail].

SUPPLEMENTARY INFORMATION:

Later in this preamble under the Additional Information section, we discuss how you can comment on this proposal and how we will handle your comments. Included in this discussion is related information about the docket, privacy, and the handling of proprietary or confidential business information. We also discuss how you can get a copy of this proposal and related rulemaking documents.

Authority for This Rulemaking

The FAA's authority to issue rules on aviation safety is found in Title 49 of the United States Code. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority.

This rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, the FAA is charged with prescribing regulations for promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce, including minimum safety standards for aircraft engines. This regulation is within the scope of that authority because it updates the existing regulations for aircraft engine standards overtorque limits.

Background

Part 33 of Title 14, Code of Federal Regulations (14 CFR part 33) prescribes airworthiness standards for original and amended type certificates for aircraft engines. The European Aviation Safety Agency (EASA) Certification Specification—Engines (CS-E) prescribes corresponding airworthiness standards for the certification of aircraft engines in Europe. While part 33 and the CS-E are similar, they differ in several respects. For applicants seeking certification under part 33 and CS-E, these differences result in additional costs and delays in the time required for certification. In addition, because the CS-E does contain specific standards for the approval of maximum overtorque limits, U.S. aircraft engine manufacturers face additional costs when seeking certification of their engine designs by the JAA/EASA for export.

Currently, part 33 does not contain explicit standards for a maximum engine overtorque limit. Engine manufacturers apply for and obtain FAA approvals of maximum overtorque limits based on the results of certification engine tests and analysis that did not directly address considerations for maximum overtorque limits.

The FAA tasked the Aviation Rulemaking Advisory Committee (ARAC),^[1] through its Engine Harmonization Working Group (EHWG), to provide advice and recommendations on proposed standards for engine overtorque. This proposed rule is based on ARAC's recommendations to the FAA.

General Discussion of the Proposed Rule

The proposed rule would establish a standard for applicants to use in applying for and obtaining approval of a maximum overtorque limit. The proposed rule would harmonize U.S. and European standards for approving engine overtorque transients for turbopropeller and turboshaft engines with free power-turbines. The proposed rule would not permit an overtorque limit for these engines when operating at the 30-second and 2-minute one engine inoperative (OEI) ratings.

This proposed rule addresses a condition that can occur on turbopropeller and turboshaft engines with free power turbines. Sudden changes in the rotorcraft/aircraft blade pitch or power demand, such as an engine failure on a twin engine rotorcraft, can cause a significant decrease in the rotor/propeller speed. For a rotorcraft engine, overtorque conditions may occur during the period the engine is accelerating the rotor system back to normal operating speeds. This NPRM proposes requirements to establish a maximum transient (20 seconds maximum) overtorque limit.

The torque transmitting components in a free turbine engine are typically the turbine blades, disks, shafts, and gears (if an internal gearbox exists). Torque has differing effects on the stress levels in these components. For example, the stresses in turbine blades and disks are dominated by centrifugal loads and, to a lesser extent, by temperature. The effects of gas loads producing torque have a minor effect on total stress in these components. The stress levels of components, such as shafts and gears, are typically dominated by the amount of torque they are transmitting. Turbine entry temperatures generally have little effect on the stress levels in shafts and gears. Typically, the time spent at maximum steady state temperature and high speed during the endurance test (required by § 33.87) results in higher turbine blade and disk stresses than would occur during a maximum overtorque event. Therefore, when the evidence of the endurance tests can be used to provide the substantiation required during certification, the requirement to run the overtorque test at maximum steady state temperature may be adjusted by other relevant factors.

Paperwork Reduction Act

The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires that the FAA consider the impact of paperwork and other information collection burdens imposed on the public. We have determined that there is no new information collection requirements associated with this proposed rule.

International Compatibility

In keeping with U.S. obligations under the Convention on International Civil Aviation, it is FAA policy to comply with International Civil Aviation Organization (ICAO) Standards and Recommended Practices to the maximum extent practicable. The FAA has determined that there are no ICAO Standards and Recommended Practices that correspond to these proposed regulations.

Regulatory Evaluation, Regulatory Flexibility Determination, International Trade Impact Assessment, and Unfunded Mandates Assessment

Changes to Federal regulations must undergo several economic analyses. First, Executive Order 12866 directs that each Federal agency shall propose or adopt a regulation only upon a reasoned determination that the benefits of the intended regulation justify its costs. Second, the Regulatory Flexibility Act of 1980 (Pub. L. 96-354) requires agencies to analyze the economic impact of regulatory changes on small entities. Third, the Trade Agreements Act (Pub. L. 96-39) prohibits agencies from setting standards that create unnecessary obstacles to the foreign commerce of the United States. In developing U.S. standards, the Trade Act requires agencies to consider international standards and, where appropriate, that they be the basis of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires agencies to prepare a written assessment of the costs, benefits, and other effects of proposed or final rules that include a Federal mandate likely to result in the expenditure by State, local, or tribal governments, in the aggregate, or by the private sector, of $100 million or more annually (adjusted for inflation with base year of 1995). This portion of the preamble summarizes the FAA's analysis of the economic impacts of this proposed rule.

Department of Transportation Order DOT 2100.5 prescribes policies and procedures for simplification, analysis, and review of regulations. If the expected cost impact is so minimal that a proposed or final rule does not warrant a full evaluation, this order permits that a statement to that effect and the basis for it be included in the preamble if a full regulatory evaluation of the cost and benefits is not prepared. Such a determination has been made for this proposed rule. The reasoning for this determination follows:

Currently, the FAA has no clear standards in part 33 for approval of a maximum overtorque limit. Engine manufacturers have obtained FAA approvals based on other certification engine tests and analysis that did not directly address the considerations for the maximum overtorque limit. This has allowed for different interpretations of the data by different FAA offices. Additionally, the Certification Specifications Engines (CS-E) contain specific standards for the approval of maximum overtorque limits. These differences result in additional costs and delays for the U.S. aircraft engine manufacturers when seeking certification of their engine designs by the EASA for export. The new proposed rule will harmonize the U.S. and European engine overtorque requirements, which will eliminate these additional costs and delays.

The FAA estimates there will be no adverse effect as the proposal would combine existing standards found in part 33 into one single standard for overtorque, and, as a result, either reduce costs or impose no net costs on aircraft engine manufacturers. This proposed rule will reduce regulatory barriers by establishing one standard consistent with a similar EASA standard. This benefit would justify its costs and reduce barriers to international trade.

Regulatory Flexibility Determination

The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA) establishes “as a principle of regulatory issuance that agencies shall endeavor, consistent with the objectives of the rule and of applicable statutes, to fit regulatory and informational requirements to the scale of the businesses, organizations, and governmental jurisdictions subject to regulation. To achieve this principle, agencies are required to solicit and consider flexible regulatory proposals and to explain the rationale for their actions to assure that such proposals are given serious consideration.” The RFA covers a wide-range of small entities, including small businesses, not-for-profit organizations, and small governmental jurisdictions.

Agencies must perform a review to determine whether a rule will have a significant economic impact on a substantial number of small entities. If the agency determines that it will, the agency must prepare a regulatory flexibility analysis as described in the RFA. However, if an agency determines that a rule is not expected to have a significant economic impact on a substantial number of small entities, section 605(b) of the RFA provides that the head of the agency may so certify and a regulatory flexibility analysis is not required. The certification must include a statement providing the factual basis for this determination, and the reasoning should be clear.

This proposed rule merely revises and clarifies FAA rulemaking procedures; the expected outcome is to reduce aircraft engine certification costs. Therefore, the FAA certifies that this proposed rule would not have a significant economic impact on a substantial number of small entities. The FAA solicits comments regarding this determination.

International Trade Impact Assessment

The Trade Agreements Act of 1979 (Pub. L. 96-39) prohibits Federal agencies from establishing any standards or engaging in related activities that create unnecessary obstacles to the foreign commerce of the United States. Legitimate domestic objectives, such as safety, are not considered unnecessary obstacles. The statute also requires consideration of international standards and, where appropriate, that they be the basis for U.S. standards. The FAA has assessed the potential effect of this proposed rule and has determined that it complies with this Act as it would reduce trade barriers by eliminating the engine-certification-requirement differences related to overtorque between the United States and European regulations.

Unfunded Mandates Assessment

Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires each Federal agency to prepare a written statement assessing the effects of any Federal mandate in a proposed or final agency rule that may result in an expenditure of $100 million or more (adjusted annually for inflation with the base year 1995) in any one year by State, local, and tribal governments, in the aggregate, or by the private sector; such a mandate is deemed to be a “significant regulatory action.” The FAA currently uses an inflation-adjusted value of $128.1 million in lieu of $100 million. This proposed rule does not contain such a mandate.

Executive Order 13132, Federalism

The FAA has analyzed this proposed rule under the principles and criteria of Executive Order 13132, Federalism. We determined that this action would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government, and, therefore, would not have federalism implications.

Environmental Analysis

FAA Order 1050.1E identifies FAA actions that are categorically excluded from preparation of an environmental assessment or environmental impact statement under the National Environmental Policy Act in the absence of extraordinary circumstances. The FAA has determined this proposed rulemaking action qualifies for the categorical exclusion identified in Chapter 3, paragraph 312d, and involves no extraordinary circumstances.

Regulations That Significantly Affect Energy Supply, Distribution, or Use

The FAA has analyzed this NPRM under Executive Order 13211, Actions Concerning Regulations that Significantly Affect Energy Supply, Distribution, or Use (May 18, 2001). We have determined that it is not a “significant energy action” under the executive order because it is not a “significant regulatory action” under Executive Order 12866, and it is not likely to have a significant adverse effect on the supply, distribution, or use of energy.

Additional Information

Comments Invited

The FAA invites interested persons to participate in this rulemaking by submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy, or federalism impacts that might result from adopting the proposals in this document. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, please send only one copy of written comments, or if you are filing comments electronically, please submit your comments only one time.

We will file in the docket all comments we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this proposed rulemaking. Before acting on this proposal, we will consider all comments we receive on or before the closing date for comments. We will consider comments filed after the comment period has closed if it is possible to do so without incurring expense or delay. We may change this proposal in light of the comments we receive.

Proprietary or Confidential Business Information

Do not file in the docket information that you consider to be proprietary or confidential business information. Send or deliver this information directly to the person identified in the FOR FURTHER INFORMATION CONTACT section of this document. You must mark the information that you consider proprietary or confidential. If you send the information on a disk or CD-ROM, mark the outside of the disk or CD-ROM and also identify electronically within the disk or CD-ROM the specific information that is proprietary or confidential.

Under 14 CFR 11.35(b), when we are aware of proprietary information filed with a comment, we do not place it in the docket. We hold it in a separate file to which the public does not have access, and we place a note in the docket that we have received it. If we receive a request to examine or copy this information, we treat it as any other request under the Freedom of Information Act (5 U.S.C. 552). We process such a request under the DOT procedures found in 49 CFR part 7.

Availability of Rulemaking Documents

You can get an electronic copy of rulemaking documents using the Internet by—

1. Searching the Federal eRulemaking Portal (http://www.regulations.gov);

2. Visiting the FAA's Regulations and Policies Web page at: http://www.faa.gov/​regulations_​policies/​; or Accessing the Government Printing Office's Web page at: http://www.gpoaccess.gov/​fr/​index.html.

You can also get a copy by sending a request to the Federal Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence Avenue SW., Washington, DC 20591, or by calling [phone]. Make sure to identify the docket number, notice number, or amendment number of this rulemaking.

List of Subjects

14 CFR Part 1

• Air transportation
• Aircraft
• Aviation safety
• Safety

14 CFR Part 33

• Air transportation
• Aircraft
• Aviation Safety
• Safety

The Proposed Amendment

In consideration of the foregoing, the Federal Aviation Administration proposes to amend parts 1 and 33 of Title 14, Code of Federal Regulations (14 CFR parts 1 and 33) as follows:

PART 1—DEFINITIONS AND ABBREVIATIONS

1. The authority citation for part 1 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.

2. Amend § 1.1 by adding the definition of “Maximum engine overtorque” in alphabetical order, to read as follows:

§ 1.1

General definitions.

* * * * *

Maximum engine overtorque, as it applies to turbopropeller and turboshaft engines incorporating free power-turbines for all ratings except one engine inoperative (OEI) ratings of two minutes or less, means the maximum torque of the free power-turbine rotor assembly, the inadvertent occurrence of which, for periods of up to 20 seconds, will not require rejection of the engine from service, or any maintenance action other than to correct the cause.

* * * * *

PART 33—AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES

3. The authority citation for part 33 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.

4. Amend § 33.7 by adding new paragraph (c)(17) as follows:

§ 33.7

Engine ratings and operating limitations.

* * * * *

(c) * * *

(17) Maximum engine overtorque for turbopropeller and turboshaft engines incorporating free power-turbines.

5. Section 33.84 is added to read as follows:

§ 33.84.

Engine Overtorque Test.

(a) If approval of a maximum engine overtorque is sought for an engine incorporating a free power turbine, compliance with this section must be demonstrated by testing.

(1) The test may be run as part of the endurance test requirement of § 33.87. Alternatively, tests may be performed on a complete engine or equivalent testing on individual groups of components.

(2) Upon conclusion of tests conducted to show compliance with this section, each engine part or individual groups of components must meet the requirements of § 33.93(a)(1) and (a)(2).

(b) The test conditions must be as follows:

(1) A total of 15 minutes run at the maximum engine overtorque to be approved. This may be done in separate runs, each being of at least 21/2 minutes duration.

(2) A power turbine rotational speed equal to the highest speed at which the maximum overtorque can occur in service. The test speed may not be more than the limit speed of take-off or OEI ratings longer than 2 minutes.

(3) For engines incorporating a reduction gearbox, a gearbox oil temperature equal to the maximum temperature when the maximum engine overtorque could occur in service; and for all other engines, an oil temperature within the normal operating range.

(4) A turbine entry gas temperature equal to the maximum steady state temperature approved for use during periods longer than 20 seconds, other than conditions associated with 30-second or 2-minutes OEI ratings. The requirement to run the test at the maximum approved steady state temperature may be waived by the FAA if the applicant can demonstrate that other testing provides substantiation of the temperature effects when considered in combination with the other parameters identified in paragraphs (b)(1), (b)(2) and (b)(3) of this section.

Issued in Washington, DC, on March 20, 2008.

John J. Hickey,

Director, Aircraft Certification Service.

Footnotes

1.  Published in the Federal Register, October 20, 1998 (63 FR 56059).