[Federal Register Volume 65, Number 171 (Friday, September 1, 2000)]
[Notices]
[Pages 53340-53341]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-22540]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Policy Statement Number ACE-00-23.1155-01]


Proposed Issuance of Policy Memorandum, In-Flight Operation of 
Propellers at Pitch Settings Below the Flight Regime for Part 23/CAR 3 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of policy statement; request for comments.

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SUMMARY: This document proposes to adopt new policy for certification 
of normal, utility, acrobatic, and commuter category turbine powered 
airplanes with propeller beta mode pitch settings.

DATE: Comments submitted must be received no later than October 2, 
2000.

ADDRESSES: Send all comments on this proposed policy statement to the 
individual identified under FOR FURTHER INFORMATION CONTACT.

FOR FURTHER INFORMATION CONTACT: Randy Griffith, Federal Aviation 
Administration, Small Airplane Directorate, Regulations and Policy 
Branch, ACE-111, 901 Locust, Room 301, Kansas City, Missouri 64106; 
telephone (816) 329-4126; fax (816) 329-4090; email: 
[email protected]>.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite your comments on this proposed policy statement, ACE-00-
23.1155-01. You may submit whatever written data, views, or arguments 
you choose. You should mark your comments, ``Comments to policy 
statement ACE-00-23.1155-01'' and submit in duplicate to the above 
address. We will consider all comments received on or before the 
closing date. We may change the proposals contained in this notice in 
light of the comments received.
    You may also send comments via the Internet using the following 
address: [email protected]. Comments sent via fax or the Internet 
must contain ``Comments to policy statement ACE-00-23.1155-01'' in the 
subject line. You do not need to submit in duplicate. Writers should 
format in Microsoft Word 97 or ASCII any file attachments that are sent 
via the Internet.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
comment concerning design evaluation and a comment about maintenance as 
two separate issues.
     For each issue, state what specific change you are 
requesting to the proposed policy memorandum.
     Include justification (for example, reasons or data) for 
each request.

The Proposed Policy

Background

    The National Transportation Safety Board (NTSB) has recommended 
rulemaking action to amend 14 CFR part 23 to require a means to prevent 
in-flight operation of the propeller at pitch settings below the flight 
regime (beta mode). For turbine engine installations, Amendment 23-7, 
Sec. 23.1155, requires that operation of the propeller controls for 
pitch settings below the flight regime have a means to prevent 
inadvertent operation. The new requirement recommended by the NTSB 
would be fundamentally different from the current Sec. 23.1155. Unless 
the airplane is certificated for such use, beta mode could not occur 
in-flight, even if intentionally commanded. The Small Airplane 
Directorate is initiating an ARAC, Aviation Rulemaking Advisory 
Committee, study to determine whether a rulemaking effort should occur.
    The FAA has taken actions to address previously certificated 
airplanes with in-flight beta capability. A fleet wide review of all 
turbopropeller powered transport, normal, utility, acrobatic, and 
commuter category airplanes was performed. As a result of the review, 
FAA issued Airworthiness Directives that required applicable Flight 
Manuals to include an operational limitation with consequence statement 
for in-flight beta operation.
    Additionally, the safety of future type certificated airplanes, 
with in-flight beta capability, or currently certificated airplanes, 
which are being modified to add an in-flight beta capability, should be 
assessed. This assessment should consider both inadvertent and 
intentional operation of propellers in pitch settings below the flight 
regime.

Inadvertent In-Flight Operation

    Regarding inadvertent operation, as previously mentioned, Amendment 
23-7 added a requirement (Sec. 23.1155) that operations of the 
propeller controls at pitch settings below the flight regime have a 
means to prevent inadvertent operation. For airplanes with a 
certification basis before Amendment 23-7 that are modified to add in-
flight beta capability, the provisions of 14 CFR part 21, 
Sec. 21.101(b) should be used to evaluate the possible unsafe nature of 
inadvertent operation of propellers in the beta regime. If it is 
determined that such operation is unsafe, the issue may be addressed by 
showing compliance with Sec. 23.1155 at Amendment 23-7 or subsequent.
    The nature of the regulatory requirement provided by Sec. 23.1155 
allows a subjective, qualitative evaluation for compliance 
determination. The intent is to prevent inadvertent operation in the 
beta mode, even if the possibility of inadvertent operation is remote. 
If an operation or feature of the design can allow in-flight, 
inadvertent placement of the control below the flight regime, the 
design does not comply with the regulation. In other words, the design 
should be evaluated considering the types of operations that will be 
seen in service. Consider items such as hardware wear modes or 
maintenance issues that may cause the control to be inadvertently 
placed or creep into the beta regime over a period of time.

Intentional In-Flight Operation

    On all future type certification projects, the Flight Manuals 
should include the appropriate operational limitations and consequence 
statement for in-flight beta operation.

Beta Lock-Out Systems

    To add a level of assurance that in-flight beta will not occur, 
some airplanes have incorporated lock-out systems. These systems 
eliminate the ability to perform this operation in flight, even if 
intentionally commanded. It is important to note that the installation 
of a beta lock-out system can not be used in lieu of the design 
requirements of Sec. 23.1155 compliance. Also, in some cases, propeller 
beta operation is used to show compliance with stopping distances in 14 
CFR part 23, Subpart B. In accordance with Subpart B, when means other 
than wheel brakes are used for determining

[[Page 53341]]

stopping distances, the means must be ``safe and reliable.'' If beta 
operation is used to show compliance with stopping distances, the 
reliability of a system that would prevent in-flight beta operation 
must be such that this capability, when required, will be available to 
comply with 14 CFR part 23, Subpart B, and 14 CFR part 21, 
Sec. 21.21(b)(2) or Sec. 21.101(b). With a systems safety analysis, you 
can determine the required reliability level for the beta lock-out 
system based on the hazard level (for example, Sec. 23.1309 
compliance).
    You should perform a systems safety analysis on airplanes with beta 
lock-out systems. This analysis will consider hazards such as the 
inability to command beta on one engine on a multiengine airplane. For 
example, If you command beta on both 2 engines during land roll-out, 
but only one propeller goes into beta mode, this might adversely affect 
ground controllability.

    Issued in Kansas City, Missouri on August 16, 2000.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 00-22540 Filed 8-31-00; 8:45 am]
BILLING CODE 4910-13-P