[Federal Register Volume 66, Number 21 (Wednesday, January 31, 2001)]
[Notices]
[Pages 8460-8461]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-2645]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Proposed Advisory Circulars; Vibration and Fatigue Evaluation of 
Airplane Propellers and Guidance Material for Fatigue Limit Tests and 
Composite Blade Fatigue Substantiation

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of availability of proposed advisory circulars and 
request for comments.

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SUMMARY: The Federal Aviation Administration (FAA) announces the 
availability of two draft advisory circulars (ACs): AC No. 20-66 
[DRAFT], Vibration and Fatigue Evaluation of Airplane Propellers, and 
AC 35.37-1[DRAFT], Guidance Material for Fatigue Limit Tests and 
Composite Blade Fatigue Substantiation.

DATES: Comments must be received on or before April 2, 2001.

ADDRESSES: Send all comments on the proposed ACs to the Federal 
Aviation Administration, Attn: Engine and Propeller Standards Staff, 
ANE-110, 12 New England Executive Park, Burlington, MA 01803-5299.

FOR FURTHER INFORMATION CONTACT: Jay Turnberg, Engine and Propeller 
Standards Staff, ANE-110, at the above address; telephone: (781) 238-
7116; fax: (781) 238-7199; e-mail: [email protected]

SUPPLEMENTARY INFORMATION:

Comments Invited

    A copy of the subject ACs may be obtained by contacting the person 
named under FOR FURTHER INFORMATION CONTACT or by downloading the draft 
ACs from the following Internet website: www.faa.gov/avr/air/acs/draftach.htm. The FAA invites interested parties to comment on the 
proposed ACs. Comments should identify the subject of the AC and be 
submitted to the individual identified under FOR FURTHER INFORMATION 
CONTACT. The FAA will consider all communications received by the 
closing date before issuing the final ACs.

Background

    The FAA issued AC 20-66, ``Vibration Evaluation of Airplane 
Propellers,'' on January 29, 1970. The FAA issued AC 35.37-1, Change 1, 
``Composite Propeller Blade Fatigue Substantiation,'' on September 7, 
1993. Since the issuance of these ACs, there have been substantial 
technological advances in the design, fabrication and continued 
airworthiness of propellers. These advances have involved the 
introduction of composite materials, the development of damage 
tolerance methodologies, and a better understanding of the propeller 
operating environment.
    The FAA has decided to revise AC 20-66 and AC 35.37-1 
simultaneously, based on the relationship between the propeller fatigue 
limits developed to show compliance with Sec. 35.37, Fatigue

[[Page 8461]]

limit tests, and the propeller vibration evaluation conducted on an 
airplane to show compliance with Secs. 23.907 and 25.907, Propeller 
vibration. To update these advisory circulars, the FAA has incorporated 
substantial contributions from the Propeller Harmonization Working 
Group (PHWG) tasked on August 17, 1994, by the Aviation Rulemaking 
Advisory Committee (ARAC). Part of the PHWG task was to clarify and 
redefine existing propeller requirements to include new standards to 
reflect recent advancement in the design and construction of composite 
material propellers. The proposed ACs would revise the Current ACs to 
address recent technological advances.

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

    Issued in Burlington, Massachusetts, on January 19, 2001.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 01-2645 Filed 1-30-01; 8:45 am]
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