[Federal Register Volume 60, Number 13 (Friday, January 20, 1995)]
[Proposed Rules]
[Pages 4116-4117]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-1543]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 35

[Docket No. 94-ANE-61; Notice No. 35-ANE-03]


Special Conditions; Hamilton Standard Model 568F Propeller

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This document proposes special conditions for the Hamilton 
Standard Model 568F propeller. This propeller is constructed using all 
composite blades, a novel and unusual design feature. Part 35 of the 
Federal Aviation Regulations (FAR's) currently does not address the 
airworthiness considerations associated with propellers constructed 
using all composite blades. This notice proposes additional safety 
standards which the Administrator finds necessary to establish a level 
of safety equivalent to that established by the airworthiness standards 
of part 35 of the FAR's.

DATES: Comments must be received on or before February 21, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 94-ANE-61, 12 New England 
Executive Park, Burlington, Massachusetts 01803-5299. Comments may be 
inspected at this location between 8:00 a.m. and 4:30 p.m., Monday 
through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:
Martin Buckman, Engine and Propeller Standards Staff, ANE-110, Engine 
and Propeller Directorate, Aircraft Certification Service, FAA, New 
England Region, 12 New England Executive Park, Burlington, 
Massachusetts 01803-5229; (617) 273-7079; fax (617) 270-2412.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rules by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified under 
ADDRESSES. All communications received on or before the closing date 
for comments, specified under DATES, will be considered before taking 
action on the proposed special conditions. The proposals contained in 
this action may be changed in light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposes special 
conditions. All comments submitted will be available, both before and 
after the closing date for comments, in the Rules Docket for 
examination by interested persons. A report summarizing each FAA-public 
contact concerned with the substance of this proposal will be filed in 
the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 94-ANE-61.'' The postcard will be date stamped and 
returned to the commenter.

Availability of Notice of Special Condition

    Any person may obtain a copy of this Notice of Special Condition by 
submitting a request to the FAA, New England Region, Office of the 
Assistant Chief Counsel, Attention: Rules Docket No. 94-ANE-61, 12 New 
England Executive Park, Burlington, Massachusetts 01803-5299.

Discussion

Background

    On January 26, 1994, Hamilton Standard applied for type 
certification for a new Model 568F propeller. This propeller is 
constructed using all composite blades, a novel and unusual design 
feature. Propellers constructed entirely of composite material have 
additional airworthiness considerations not currently addressed by part 
35 of the FAR's. Those additional airworthiness considerations 
associated with propellers constructed using all composite blades are 
propeller integrity following a bird strike, propeller integrity 
following a lightning strike, and propeller fatigue strength when 
exposed to the deteriorating effects of in-service use and the 
environment.

Type Certificate Basis

    Under the provisions of Sec. 21.17 of the FAR's, Hamilton Standard 
must show that the Model 568F propeller meets the requirements of the 
applicable regulations in effect on the date of the application. Those 
FAR's are Sec. 21.21 and part 35, effective February 1, 1965, as 
amended.
    The Administrator finds that the applicable airworthiness 
regulations in part 35, as amended, do not contain 
[[Page 4117]] adequate or appropriate safety standards for the Model 
568F propeller because it is constructed using composite material. 
Therefore, the Administrator proposes special conditions under the 
provisions of Sec. 21.16 of the FAR's to establish a level of safety 
equivalent to that established in part 35.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49 of the FAR's after public notice and opportunity for 
comment, as required by Secs. 11.28 and 11.29(b), and become part of 
the type certification basis in accordance with Sec. 21.101(b)(2).

Novel or Unusual Design Features

    The Hamilton Standard Model 568F propeller incorporates propeller 
blades constructed using composite material. This material has fibers 
that are woven or aligned in specific directions to give the material 
directional strength properties. These properties depend on the type of 
fiber, the orientation and concentration of fiber, and matrix material. 
Composite materials could exhibit multiple modes of failure. Propellers 
constructed of composite material must demonstrate airworthiness when 
considering these novel design features.
    The requirements of part 35 of the FAR's were established to 
address the airworthiness considerations associated with wood and metal 
propellers used primarily on reciprocating engines. Propeller blades of 
this type are generally thicker than composite blades, and have 
demonstrated good service experience following a bird strike. Propeller 
blades constructed using composite material are generally thinner when 
used on turbine engines, and are typically installed on high 
performance aircraft. High performance aircraft generally fly at high 
airspeeds with correspondingly high impact forces associated with a 
bird strike. Thus, composite propellers must demonstrate propeller 
integrity following a bird strike.
    In addition, part 35 of the FAR's do not currently require a 
demonstration of propeller integrity following a lightning strike. No 
safety considerations arise from lightning strikes on propellers 
constructed of metal because the electrical current is safely conducted 
through the metal blade without damage to the propeller. Fixed pitched, 
wood propellers are generally used on engines installed on small, 
general aviation aircraft that typically do no encounter fling 
conditions conducive to lightning strikes. Composite propeller blades, 
however, may be used on turbine engines and high performance aircraft 
which have an increased risk of lightning strikes. Composite blades may 
not safely conduct of dissipate the electrical current from a lightning 
strike. Severe damage can result if the propellers are not properly 
protected. Therefore, composite blades must demonstrate propeller 
integrity following a lightning strike. Information on testing for 
lightning protection is set out in SAE Report AE4L, entitled, 
``Lightning Test Waveforms and Techniques for Aerospace Vehicles and 
Hardware,'' dated June 20, 1978.
    Lastly, the current certification requirements address fatigue 
evaluation only of metal propeller blades or hubs, and those metal 
components of non-metallic blade assemblies. Allowable design stress 
limits for composite blades must consider the deteriorating effects of 
the environment and in-service use, particularly those effects from 
temperature, moisture, erosion and chemical attack. Composite blades 
also present new and different considerations for retention of the 
blades in the propeller hub.

Conclusion

    This action affects only the Hamilton Standard Model 568F propeller 
and future propeller models within this series. It is not a rule of 
general application, and it affects only the manufacturer who applied 
to the FAA for approval of this propeller model.

List of Subjects in 14 CFR Part 35

    Air Transportation, Aircraft, Aviation safety, Safety.

    The authority citation for these special conditions continues to 
read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421, 1423; 49 U.S.C. 106(g).

The Proposed Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration (FAA) proposes the 
following Special Conditions for the Hamilton Standard Model 568F 
Propeller.
    (a) For purposes of these special conditions, a hazardous condition 
is considered to exist for each of the following conditions:
    (1) Loss of the propeller blade, or a major portion of a blade.
    (2) Overspeed of the propellers.
    (3) Unintended movement of the blade below the established minimum 
inflight blade angle, or to an angle that results in excessive drag.
    (4) The inability to feather the propeller when necessary.
    (b) In addition to the requirements of Federal Aviation Regulation 
part 35, the following must be shown:
    (1) BIRD STRIKE
    For propeller of composite construction it must be shown that:.
    The propeller can withstand a 4 pound bird strike at the blade's 
critical radial location when operating at takeoff RPM and liftoff (Vr) 
speed of a typical aircraft, without giving rise to a hazardous 
condition and while maintaining the capability to be feathered.
    (2) LIGHTNING STRIKE
    A lightning strike a propeller of a composite construction shall 
not result in a hazardous condition. The propeller shall be capable of 
continued safe operation.
    (3) FATIGUE EVALUATION
    A fatigue evaluation must be provided and the fatigue limits 
determined for each propeller hub, blade, and each primary load 
carrying component of the propeller. The fatigue evaluation must 
consider all known and reasonable foreseeable vibration and cyclic load 
patterns that may be encountered in service. The fatigue limits must 
account for the efforts of in-service deterioration, such as impact 
damage, nicks, grooves, galling, or bearing wear; for variations in 
production material properties; for environmental effects such as 
temperature, moisture, erosion, chemical attack, etc., that cause 
deterioration. Issued in Burlington, Massachusetts, on January 12, 
1995.
Jay Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 95-1543 Filed 1-19-95; 8:45 am]
BILLING CODE 4910-13-M