[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]
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