[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
