Document ID: FAA-2007-28502-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Standards; Aircraft Engine Standards Overtorque Limits
Posted Date: 2008-03-26T04:00Z

[Federal Register: March 26, 2008 (Volume 73, Number 59)]
[Proposed Rules]               
[Page 15955-15959]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26mr08-30]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 1 and 33

[Docket No. 2007-28502; Notice No. 07-09]
RIN No. 2120-AJ06

 
Airworthiness Standards; Aircraft Engine Standards Overtorque 
Limits

AGENCY: Federal Aviation Administration (FAA) DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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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.

[[Page 15956]]

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 (781) 238-7114; facsimile (781) 238-
7199; electronic mail ``Timoleon.Mouzakis@faa.gov''. 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 (781) 238-7044; facsimile (781) 238-
7055; electronic mail Vincent.Bennett@faa.gov.

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

[[Page 15957]]

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 
Sec.  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

[[Page 15958]]

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 (202) 267-9680. 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 Sec.  1.1 by adding the definition of ``Maximum engine 
overtorque'' in alphabetical order, to read as follows:

Sec.  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 Sec.  33.7 by adding new paragraph (c)(17) as follows:

Sec.  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:

[[Page 15959]]

Sec.  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 Sec.  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 Sec.  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 
2\1/2\ 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.
 [FR Doc. E8-6148 Filed 3-25-08; 8:45 am]

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