[Federal Register Volume 65, Number 70 (Tuesday, April 11, 2000)]
[Notices]
[Pages 19423-19424]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-8848]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Proposed Advisory Circular 25.905-X, Minimizing the Hazards From 
Propeller Blade and Hub Failures

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of availability of proposed Advisory Circular (AC) 
25.905-X and request for comments.

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[[Page 19424]]

SUMMARY: This notice announces the availability of and requests comment 
on a proposed advisory circular (AC) that provides methods acceptable 
to the Administrator for showing compliance with the airworthiness 
standards for propeller installations on transport category airplanes. 
The guidance provided in the AC supplements the engineering and 
operational judgment that must form the basis of any compliance 
findings relative to design precautions that should be taken to 
minimize the hazards to an airplane in the event that a propeller blade 
fails or is released by a hub failure. This notice is necessary to give 
all interested persons an opportunity to present their views on the 
proposed AC.

DATES: Comments must be received on or before June 12, 2000.

ADDRESSES: Send all comments on the proposed AC to: Federal Aviation 
Administration, Attn: Michael Dostert, FAA, Transport Airplane 
Directorate, Aircraft Certification Service, Propulsion/Mechanical 
Systems Branch, ANM-112, 1601 Lind Avenue SW., Renton, Washington 
98055-4056. Comments may be inspected at the above address between 7:30 
a.m. and 4:00 p.m. weekdays, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Jill DeMarco, Program Management 
Branch, ANM-114, Transport Airplane Directorate, FAA, 1601 Lind Avenue 
SW., Renton, Washington 98055-4056; telephone (425) 227-1313.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to comment on the proposed AC by 
submitting such written data, views, or arguments as they may desire. 
Commenters must identify the AC by title and submit comments in 
duplicate to the address specified above. The Transport Airplane 
Directorate will consider all communications received on or before the 
closing date for comments before issuing the final AC.

Availability of Proposed AC

    The proposed AC can be found and downloaded from the Internet at 
http://www.faa.gov/avr/air/airhome.htm, at the link titled ``Draft 
AC's'' under the ``Available Information'' drop-down menu. A paper copy 
of the proposed AC may be obtained by contacting the person named above 
under the caption ``FOR FURTHER INFORMATION CONTACT.''

Discussion

    Proposed AC 25.905-X, ``Minimizing the Hazards from Propeller Blade 
and Hub Failures,'' has been prepared to provide guidance on one means 
of demonstrating compliance with the requirements of Sec. 25.905, 
``Propellers,'' of Title 14, Code of Federal Regulations (CFR) part 25, 
commonly referred to as part 25 of the Federal Aviation Regulations 
(FAR). Part 25 contains the airworthiness standards applicable to 
transport category airplanes.
    The means of compliance described in proposed AC 25.905-X is 
intended to provide guidance to supplement the engineering and 
operational judgment that must form the basis of any compliance 
findings relative to paragraph Sec. 25.905(d). That paragraph addresses 
design precautions that should be taken to minimize the hazards to an 
airplane in the event that a propeller blade fails or is released by a 
hub failure.
    In accordance with Sec. 25.905(d), the hazards that must be 
considered include:
    1. Damage to structure and vital systems due to the impact of a 
failed or released blade, and
    2. The consequent unbalance created by such failure or release.
    The proposed AC addresses the hazards associated with damage 
created by the impact of failed or released propeller blades, and 
provides a discussion of design practices to minimize such hazards. 
However, it does not address the hazard associated with unbalance 
created by such failure or release.

Harmonization of Standards and Guidance

    The proposed AC is based on recommendations submitted to the FAA by 
the Aviation Rulemaking Advisory Committee (ARAC). The FAA tasked ARAC 
(63 FR 50954, September 23, 1998) to provide advice and recommendations 
on ``harmonizing'' certain sections of part 25 (including Sec. 25.1183) 
with the counterpart standards contained in Joint Aviation Requirements 
(JAR) 25. The goal of ``harmonization tasks,'' such as this, is to 
ensure that:
     Where possible, standards and guidance do not require 
domestic and foreign parties to manufacture or operate to different 
standards for each country involved; and
     The standards and guidance adopted are mutually acceptable 
to the FAA and the foreign aviation authorities.
    The guidance contained in the proposed AC has been harmonized with 
that of the JAA, and provides a method of compliance that has been 
found acceptable to both the FAA and JAA.

    Issued in Renton, Washington, on March 31, 2000.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-8848 Filed 4-10-00; 8:45 am]
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