[Federal Register Volume 59, Number 212 (Thursday, November 3, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-27291]
[[Page Unknown]]
[Federal Register: November 3, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 35
[Docket No. 94-ANE-50; Notice No. 35-ANE-01]
Special Conditions; Hamilton Standard Model 247F Propeller
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This notice proposes special conditions for the Hamilton
Standard Model 247F propeller with electronic propeller and pitch
control system. The applicable regulations currently do not contain
adequate or appropriate safety standards for constant speed propellers
with electronic propeller and pitch control. This notice proposes the
additional safety standards which the Administrator considers necessary
to establish a level of safety equivalent to that established by the
airworthiness standards of part 35 of the Federal Aviation Regulations
(FAR).
DATES: Comments must be submitted on or before December 19, 1994.
ADDRESSES: Comments on this proposal may be submitted in triplicate to:
Federal Aviation Administration (FAA), New England Region, Office of
the Assistant Chief Counsel, Attention: Rules Docket No. 94-ANE-50, 12
New England Executive Park, Burlington, Massachusetts, 01803-5299.
Comments must be marked: Docket No. 94-ANE-50. 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; telephone (617) 238-7112; fax (617) 238-
7199.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed special conditions 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 by the
Administrator before taking action on the proposal. The proposal
contained in this notice may be changed in light of the comments
received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed special
conditions. All comments submitted will be available in the Rules
Docket for examination by interested persons, both before and after the
closing date for comments. A report summarizing each substantive public
contact with FAA personnel concerning this proposal will be filed in
the docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit with those comments a
self-addressed, stamped postcard on which the following statement is
made: ``Comments to Docket No. 94-ANE-50.'' 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-50, 12 New
England Executive Park, Burlington, Massachusetts, 01803-5299.
Discussion
Background
On March 8, 1993, Hamilton Standard applied for an amendment to the
type certificate of Model 247F propeller. This propeller uses a new
electronic propeller and pitch control system in place of the primary
governor control and synchrophaser unit.
The existing propeller pitch control is normally monitored by a
governor which senses propeller speed and adjusts the pitch to absorb
the engine power and thus keeps the propeller at the correct RPM. When
the primary governor fails, the propeller pitch is controlled by an
overspeed governor.
This type of system is conventional and its airworthiness
considerations are addressed by part 35 of the FAR's.
Hamilton Standard requests special conditions to install an
electronic propeller and pitch control in place of the primary governor
control and synchrophaser unit for the Model 247F propeller. This
control is designed to operate with existing mechanical and hydraulic
interface of the engine and propeller.
Electronic propeller and pitch controls introduce potential
failures that can result in unsafe conditions. These types of failures
are not addressed by the requirements of part 35. These failures can
lead to the following possible unsafe conditions:
(1) Loss of control of the propeller
(2) Instability of a critical function
(3) Unwanted change in propeller pitch causing improper thrust/
overspeed
(4) Unwanted action of a critical control function resulting in
propeller flat pitch or reverse.
Certification issues that must be addressed are possible loss of
aircraft-supplied electrical power, aircraft supplied data, failure
modes, environmental effects including lightning strikes and high
intensity radiated fields (HIRF) and software design.
The FAA finds that under the provisions of Sec. 21.16 of the FAR,
additional safety standards must be applied to the Hamilton Standard
electronic propeller control for Model 247F propellers to demonstrate
that it is capable of acceptable operation.
Type Certification Basis
Under the provisions of Sec. 21.17 of the FAR, Hamilton Standard
must show that the Model 247F 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 adequate or
appropriate safety standards for the Model 247F propeller. Therefore,
the Administrator proposes special conditions under the provisions of
Sec. 21.16 to establish a level of safety equivalent to that
established in the regulations.
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
Because of the unusual design features of the Hamilton Standard
247F propeller with electronic propeller and pitch control, the FAA
proposes special conditions under Sec. 21.16 of the FAR.
Conclusion
This action affects only the Hamilton Standard Model 247F propeller
with a new system of electronic propeller and pitch control. It is not
a rule of general applicability and affects only the manufacturer who
applied to the FAA for approval of these features on the propeller.
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);
and 14 CFR 11.49 and 21.16.
The Proposed Special Conditions
Accordingly, the FAA proposes the following special conditions as
part of the type certification basis for the Hamilton Standard 247F
Model propeller with electronic propeller and pitch control system.
Considering that electronic propeller and pitch controls introduce
potential failures that can result in unsafe conditions, the following
special conditions are proposed:
(a) Each propeller and pitch control system which relies on
electrical and electronic means for normal operation must:
(1) Be designed and constructed so that any failure or malfunction
of aircraft-supplied power or data will not result in an unacceptable
change in propeller pitch setting or prevent continued safe operation
of the propeller.
(2) Be designed and constructed so that no single failure or
malfunction, or probable combination of failures of electrical or
electronic components of the propeller control system, result in an
unsafe condition.
(3) Be tested to its environmental limits including transients
(variations) caused by lightning and high intensity radiated fields
(HIRF) and demonstrate no adverse effects on the control system
operation and performance or resultant damage. These tests shall
include, but not be limited to, the following:
(i) Lightning strikes, such as multiple-stroke and multiple-burst
(ii) Pin-injected tests to appropriate wave forms and levels
(iii) HIRF susceptibility tests
(4) Be demonstrated by analysis/tests that associated software is
designed and implemented to prevent errors that would result in an
unacceptable change in propeller pitch or an unsafe condition.
(5) Be designed and constructed so that a failure or malfunction of
electrical or electronic components in the propeller control system
will not prevent safe operation of any remaining propeller that is
installed on the aircraft.
Issued in Burlington, Massachusetts, on October 27, 1994.
Jay Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 94-27291 Filed 11-2-94; 8:45 am]
BILLING CODE 4910-13-M
