[Federal Register Volume 61, Number 73 (Monday, April 15, 1996)]
[Notices]
[Pages 16521-16525]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-9250]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION -
In-Flight Beta Operations
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of public meeting.
-----------------------------------------------------------------------
SUMMARY: This notice announces a public meeting which is being held by
the Federal Aviation Administration (FAA) for the purpose of soliciting
and reviewing information from the public on what type of FAA action
would be appropriate to prevent future occurrences of in-flight beta
operation on all turboprop airplanes certified in the transport
category under part 25 of the Federal Aviation Regulations (FAR) and
certified in the commuter category under part 23 of the FAR, Special
Federal Aviation Regulations (SFAR) 23 and SFAR 41. Numerous reports
have been made relating to intentional or inadvertent operation of the
propellers in the beta range during flight. Initial examination of
these events indicate that the throttle lever flight idle stop has not
adequately prevented beta operation during flight and that additional
actions to prevent such operation may be appropriate. In order to make
a determination what action to take, the FAA is holding a public
meeting for the purpose of soliciting and reviewing comments from the
public. The FAA will evaluate all comments and ideas in deciding
whether rulemaking (including airworthiness directive action) is
warranted for airplanes currently type certificated and equipped with
turboprop engines.
DATES: The public meeting is scheduled for Tuesday and Wednesday, June
11 and 12, 1996. On-site registration will begin at 7:30 a.m. on
Tuesday, June 11, and the public meeting will begin at 8:30 a.m. on
that day.
registration: Persons planning to attend the public meeting should pre-
register by contacting Mark Quam, Standardization Branch, ANM-113,
Transport Airplane Directorate, Aircraft Certification Service, 1601
Lind Ave. SW, Renton, WA 98055-4056, telephone (206) 227-2145; fax
(206) 227-1149; internet address [email protected]
Arrangements for oral presentation must be made by May 10, 1996.
ADDRESSES: The public meeting will be held at the Red Lion Hotel
Seattle Airport, 18740 Pacific Highway South, Seattle, WA 98188,
telephone (206) 246-8600. Guest room reservations should be made in
advance. A block of guest rooms has been reserved for meeting
participants at the Red Lion Hotel at a group rate of $74.77 (plus
tax). This block of rooms will be held until May 20, 1996. Persons
planning on attending the public meeting should contact the hotel
directly for room reservations and identify themselves as participants
in the FAA In-flight Beta
[[Page 16522]]
Operations Public Meeting to receive the special room rate.
FOR FURTHER INFORMATION CONTACT:
For information regarding turbopropeller airplanes certificated in the
transport category under part 25 (14 CFR part 25): Mark Quam, Aerospace
Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane
Directorate, Aircraft Certification Service, 1601 Lind Avenue, SW,
Renton, WA 98055-4056; telephone (206) 227-2145; fax (206) 227-1149;
internet address [email protected] For information regarding
turbopropeller airplanes certificated in the commuter category under
part 23 (14 CFR part 23), SFAR 23 and SFAR 41: Mike Kiesov, Aerospace
Engineer, FAA Small Airplane Directorate, Aircraft Certification
Service, 1201 Walnut Street, Suite 900, Kansas City, Missouri 64106,
telephone (816) 426-6934; fax (816) 426-2169.
SUPPLEMENTARY INFORMATION: Notice is herewith given of a public meeting
to be on Tuesday and Wednesday, June 11 and 12, 1996, at the Red Lion
Hotel Seattle Airport, Seattle, Washington. The purpose of this meeting
is to hear comments from the general public regarding what type of FAA
action, if any, would be appropriate to prevent future occurrences of
in-flight beta operation on turboprop airplanes certified in the
transport category under part 25 of the FAR and certified in the
commuter category under part 23, SFAR 23 and SFAR 41. The FAA will
consider information presented at the public meeting in the course of
making its decision as to the type of action to take on this issue.
Attendance is open to the interested public, but will be limited to the
space available.
Request To Be Heard
Persons planning to present data or comments at the public meeting
are requested to provide the FAA an abstract of their presentation no
later than May 10, 1996. The abstract should include an estimate of the
time needed to make the presentation, and should be sent to Mark Quam,
Aerospace Engineer, Standardization Branch, ANM-113, FAA Transport
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue,
SW, Renton, Washington 98055-4056; internet address
[email protected] Following each presentation, a discussion
period will be allowed. Requests received after the date specified
above will be scheduled only if time is available during the meeting;
however, the name of those individuals may not appear on the written
agenda for the public meeting.
The FAA will prepare an agenda of speakers who will be available at
the meeting. Every effort will be made to accommodate as many speakers
as possible. The amount of time allocated to each speaker may be less
than the amount of time requested.
Discussion
Sections 23.1155 and 25.1155 (``Reverse thrust and propeller pitch
settings below the flight regime'') of the FAR (14 CFR 23.1155 and
25.1155) state:
``* * * each control for * * * propeller pitch settings below
the flight regime must have a means to prevent its inadvertent
operation. The means must have a positive lock or stop at the flight
idle position and must require a separate and distinct operation by
the crew to displace the control from the flight regime * * *''
Reverse thrust and propeller settings below the flight regime are
referred to as beta operation. ``Beta'' is the range of propeller
operation intended for use during taxi, ground idle and reverse
operations, as controlled by the power lever settings aft of the flight
idle stop.
Generally, compliance with this requirement has been the
installation of a stop or detent that requires a separate distinct
pilot action (such as lifting the power levers up and beyond the stop
or detent) to displace the power levers from the flight regime. Despite
these requirements of Secs. 23.1155 and 25.1155, the FAA has received
fifteen reports over the last seven years involving airplanes equipped
with turboprop engines in which the propeller control was intentionally
or inadvertently displaced from the flight regime into the beta range
during flight.
Of those fifteen in-flight beta events, five have been classified
as accidents. In-flight beta operation that preceded these accidents
has resulted in two different kinds of consequences:
1. Permanent engine damage and total loss of thrust on all engines
when the propellers that were operating in the beta range drove the
engines to overspeed; and
2. Loss of airplane control because at least one propeller operated
in the beta range during flight.
In the most recent accident, both engines of a turboprop airplane
lost power during descent after eight seconds of operation with the
propellers in beta range. The propellers subsequently drove the engines
into overspeed, which resulted in internal engine failure.
In light of this service history, the FAA is issuing this notice of
public meeting to provide an opportunity for the general public to
participate in deciding what type of action would be appropriate to
prevent future occurrences of in-flight beta operation on all turboprop
airplanes certified in the transport category under part 25 and
certified in the commuter category under parts 23, SFAR 23 and SFAR 41.
Interested persons are encouraged to provide information that describes
what they consider the best action (if any) to be taken to correct the
problem. In addition, the FAA is especially interested in comments and
viewpoints on the following items:
Item 1. Most turboprop propeller control designs allow the pilot to
intentionally move the power levers aft of the flight idle stop in
flight into the beta range while the airplane is in flight.
a. Do you know of any occurrence of in-flight unintentional
movement of the power levers aft of the flight idle regime? If so,
please provide all the incident history details.
b. Do you consider the intentional selection of in-flight beta a
design issue or an aircrew training issue? Why is it a design issue or
a training issue?
c. What training methods or systems/design concepts would best deny
the pilot the capability to access beta inflight? Why?
Based on the FAA's past experience with airworthiness directives
that have required increased flightcrew training and intensified AFM
warnings concerning the use of beta during flight, these actions alone
may not provide an adequate level of safety for turbopropeller
airplanes certificated in the commuter category under SFAR 23 and SFAR
41 and airplanes certified in the transport category.)
Item 2. The FAA is considering requiring ``beta lockout system''
retrofits on all turboprop airplanes certified in the transport
category and certified in the commuter category under part 23, SFAR 23
and SFAR 41. (A beta lockout system is an electro-mechanical system
that typically uses air-ground sensor logic, wheel spin-up, air-ground
(squat) switch activation, gear-up switch activation, or combinations
of these to activate (or deactivate) a solenoid that physically blocks
the power levers from being retracted beyond the flight idle stop and
prevents obtaining beta in flight.)
Until recently, the collective operational history of these
airplanes did not indicate that a problem existed beyond a few models.
Recent experience, however, indicates that the flight idle stop will
not prevent beta operation during flight, and that beta operation
during flight could occur on
[[Page 16523]]
any airplane equipped with a turboprop engine(s) unless the airplane
design is such that it will actually prevent a beta-related event from
occurring. Service experience has not been an adequate predictor of
beta lockout problems and does not justify exemption from any retrofit
requirement.
If the FAA was to consider a system that would deny the pilot the
capability of accessing beta inflight (i.e., a beta lockout system):
a. Should airworthiness directive(s) be issued requiring the
installation of a beta lockout system that would prevent the pilot from
obtaining the beta model during flight, unless the airplane has been
certified for in-flight beta operation? Why or why not?
b. Should rulemaking require installation of a beta lockout system
under parts 91, 121, and 135 of the FAR (14 CFR parts 91, 121, and
135)? Why or why not?
Item 3. Of the existing systems that will deny the pilot the
capability to access beta in flight?
a. What airplanes are these systems used on?
b. What are the costs of these systems?
Design Objectives
The FAA also invites comments from the public regarding the design
objectives that could be used to prevent intentional and inadvertent
selection of beta operation during flight. The following design
objectives, or design objectives altered as a result of the public
meeting, would be used to evaluate systems that would prevent obtaining
the beta range in flight if required by FAA rulemaking actions in the
future:
Beta Lockout General Design Objectives
Objective 1. Provide a means (``beta lockout'') in the beta control
system to prevent or deter the flightcrew from either intentionally or
inadvertently selecting the propeller beta range during flight. The FAA
would consider a ground override feature for use in the event failure
of the beta lockout system inhibits the selection of beta for landing
or rejected takeoff.
Basis for Objective 1: Data from the fifteen reports involving
inadvertent or deliberate selection of beta operation during flight
indicate that the flight idle stop does not prevent beta operation
during flight; beta operation can occur on any airplane unless the
airplane design prevent such an occurrence.
Objective 2. Automatic arming of the beta lockout system.
Basis for Objective 2: The pilot may inadvertently put the
propellers into the beta range during flight after forgetting to
manually arm the beta lockout system.
Objective 3. Installation of beta lockout system circuit breakers
(separate breakers for the indication systems) in such a manner as to
deter the flightcrew from using the circuit breakers as a lockout
override.
Basis for Objective 3: Service history has indicated that pilots
have pulled circuit breakers to disarm beta lockout systems that use
wheel spin-up signals or air/ground logic. Typically, these beta
lockout system designs did not allow beta operation in a timely manner
when landing on contaminated runways.
Objective 4. Inclusion of an indication system in the beta lockout
system design that shows when the beta lockout system's lock:
a. Fails to engage or does not remain engaged while airborne.
Basis for Objective 4a: The flightcrew should be advised when the
beta lockout system fails to engage at liftoff or when it fails to
remain engaged during flight, even though the failure condition may be
relatively remote. An amber caution light is recommended. Without a
caution light to indicate that the beta lockout system has failed to
engage or has not remained engaged, the possibility exists that the
pilot will inadvertently select beta during flight. Further, the
flightcrews may become dependent on the beta lockout system functioning
properly, thereby increasing the potential that the flightcrew will
inadvertently select beta during flight, following a failure of the
beta lockout system.
b. Fails to disengage or does not remain disengaged while on the
ground. The indication should remain ``on'' or ``latched'' after
landing so that maintenance action is initiated prior to the next
flight.
Basis for Objective 4b: An amber caution light is recommended. If
during the landing, the beta lockout system fails to disengage upon
landing or does not remain disengaged during the landing or takeoff
roll, beta will not be available on the ground. The landing performance
of airplanes equipped with turboprop engines is predicated on the
availability of ground idle, which is part of the beta range. This
condition is a potential hazard if the landing is field-length limited.
Overruns are more likely to occur if operating under part 91
(unfactored field lengths); however, the risks are also present if
operating under parts 121 or 135 (factored field lengths). For this
reason, the flightcrew should be advised if the beta lockout system
fails to disengage on the ground.
Objective 5. Include a method to ensure that the beta indication
system does not flash messages from the time of the takeoff power
setting speed until the airplane reaches a minimum of 400 feet above
ground level (AGL), unless immediate crew action is required to prevent
an unsafe condition.
Basis for Objective 5: The concern is that the pilot not be
distracted during the critical takeoff phase by a failure that in
itself is not catastrophic.
Beta Lockout System and Indication System Reliability Design Objectives
Objective 6. Demonstration that beta lockout systems designed for
commuter (SFAR 23/41) and transport category airplanes comply with all
applicable subparagraphs of parts 23 and 25, respectively.
Basis for Objective 6: This is a reminder that the proposed
objectives are in addition to the FAR requirements, which must also be
complied with.
Objective 7. Design the beta lockout system to ensure that
inadvertent access to beta during flight is improbable (a failure rate
of 1 x 10 E-5 or less per operating hour).
Basis for Objective 7: The flightcrews may become dependent on the
beta lockout system functioning properly, potentially increasing the
possibility that the flightcrew will inadvertently select beta during
flight following a beta lockout system failure. The beta lockout design
should provide failure protection in that it would make inadvertent
access by the flightcrew to in-flight beta operation improbable.
Objective 8. Design of a system that will ensure that a single
failure does not disable both the lockout system and the indication
system.
Basis for Objective 8: Certain beta lockout system designs prevent
accessibility to beta operation on the ground if electrical power to
the beta lockout systems is lost during flight. However, the pilot
still needs to be informed, upon landing, that beta may not be
available; therefore, the warning system source of power should be
independent of the beta lockout system source of power.
Objective 9. Demonstration that the probability of the failure of
both the beta lockout system and the beta lockout indication is
extremely remote (a failure rate of 1 x 10 E-7 or less per operating
hour).
Basis for Objective 9: If flightcrews become dependent on the beta
lockout system functioning properly, the potential exists for the
flightcrew to inadvertently select beta during flight. Therefore, the
beta lockout and indication systems should be reliable.
Objective 10. For systems that do not have a beta override
(mechanism or
[[Page 16524]]
switch), demonstration that any failure or combination of failures that
will lock out the flightcrew's capability to obtain the propeller beta
range during landing (provided it is not detectable prior to landing)
is improbable (a failure rate of 1 x 10 E-5 or less per operating
hour).
Basis for Objective 10: For turbopropeller-powered
airplanes,landing with beta locked out on field length-limited runways
may be hazardous. Overruns are more likely to occur if operating under
part 91 (unfactored field lengths); however, the risks are also present
if operating under parts 121 and 135 (factored field lengths) on wet
and contaminated runways.
Objective 11. Design of a system that will ensure that the
probability of failure of the beta lockout system (with independent
locks), which prevents one engine from obtaining reverse pitch while
allowing the other engine(s) to go into reverse pitch (beta), is 1 x
10-\7\ or less.
Basis for Objective 11: Certain failures may cause asymmetric
thrust in certain beta lockout system designs if the lockouts for each
lever are independent.
Objective 12. Coordination with the cognizant FAA Aircraft
Evaluation Group of any required system maintenance, inspections, or
functional checks that are required to achieve the reliability of beta
lockout systems as iterated in the objectives described above.
Basis of Objective 12: This is to ensure that the inspections or
functional checks are contained in the appropriate maintenance
documents.
Airplane Flight Manual (AFM) Information
Objective 13. Inclusion of an AFM limitation that prohibits use of
beta during flight.
Basis for Objective 13: The flightcrews should continue to be
advised not to use beta during flight. The remote possibility still
exists that the beta lockout system may fail to provide protection
during flight; this does not constitute a hazard if the pilot does not
select beta during flight.
Objective 14. Inclusion in the AFM of approved abnormal/emergency
procedures for failure indications if the system's lock has failed to
engage or does not remain engaged while in flight or on the ground (as
specified in the previous paragraphs).
Basis for Objective 14: The flightcrew should be advised of what or
what not to do if they receive a warning.
Objective 15. Inclusion of information in the AFM that prohibits
initiating flight with the beta lockout system inoperative unless the
beta lockout system is capable of being permanently engaged in the
locked position. For this scenario, the information should provide FAA-
approved takeoff and landing field lengths (based on tests) for
landings with the propellers set at the flight idle power setting.
Basis for Objective 15: Dispatch without beta lockout system in-
flight protection is considered unsafe unless the airplane has been
approved for in-flight beta operation. Dispatch with a failed or
deactivated beta lockout system would be acceptable if access to beta
is physically prevented and the FAA-approved takeoff and landing field
lengths, based on tests, have been provided in the AFM for the flight
idle power setting.
Beta Override Design Objectives (The Override System Could Be Optional)
Objective 16. Inclusion of an indication to the flightcrew that the
override (mechanism or switch) has been used. The indication system
should include an independent annunciation, or should be connected to
the master caution system.
Objective 17. A design that will ensure that the flightcrew is not
able to reset the override mechanism or switch once override has been
used.
Objective 18. A design that will ensure that the activation of the
override system is enunciated to prevent subsequent takeoffs until the
override mechanism or switch has been reset by maintenance action. As
an example, include the override activation in the takeoff
configuration warning system (or similar warning system).
Basis for Objectives 16, 17, and 18: Typical beta lockout systems
currently use wheel spin-up, squat switch activation, gear-up switch
activation, or combinations of these. Certain airplanes, especially
those with low wings and without ground spoilers, have a tendency to
float during landing. In the case of these airplanes, the application
of beta may be delayed on a wet runway because, while the airplane is
floating, the ground logic or the wheel spin-up may not activate
immediately.
Landing performance of turbopropeller-powered airplanes is based on
ground idle availability, which is part of the beta range.
Turbopropeller-powered airplanes landing on field length-limited
runways with delayed beta application, or without beta after the beta
lockout system fails to disengage, presents a potential hazard.
Overruns are more likely to occur if operating under part 91
(unfactored field lengths); however, the risks are also present if
operating under part 121 or 135 (factored field lengths) on a wet
runway. There are several acceptable methods that may be used to
overcome the deficiencies of the squat switch or wheel spin-up logic,
such as the use of an override switch or the use of a radar altimeter.
Because of the safety concerns discussed above and the concerns
expressed by airplane manufacturers, the FAA is considering allowing a
beta override in the design objectives if the beta override is used for
emergency use only and has the design constraints specified in the
paragraphs presented above. The FAA is concerned that the flightcrew
may reset the annunciation without reporting that they had utilized the
beta override feature of the beta lockout system either in the air or
after failure of the beta lockout system on the ground. Therefore, it
appears that the design of the override system should provide
enunciation that would prevent subsequent takeoffs after override
activation, as recommended above.
If the manufacturer's airplane design already has a beta lockout
system installed, the FAA may request a review of that system using the
design criteria that evolve from this public meeting. If the existing
beta lockout system design does not fully comply with the design
criteria, the FAA may request that the airplane manufacturer develop a
method to comply with these criteria, or to provide justification as to
why its design provides an equivalent level of safety.
Public Meeting Procedures
Persons who plan to attend the public meeting should be aware of
the following procedures which are established to facilitate the
workings of the meeting.
1. The meeting will be open on a space available basis to all
persons registered. If practicable, the meeting will be accelerated to
enable adjournment in less than the time scheduled.
2. There will be no admission fee or other charge to attend or
participate in the meeting. The opportunity to speak will be available
to all persons, subject to availability of time.
3. Representatives of the FAA will preside over the meeting. A
panel of FAA personnel involved in this issue will be present.
4. The FAA will try to accommodate all questions, time permitting.
However, the FAA reserves the right to exclude some questions, if
necessary, to present a balance of viewpoints and issues.
5. The meeting will be recorded by a court reporter. Anyone
interested in
[[Page 16525]]
purchasing the transcript should contact the court reporter directly. A
copy of the court reporter's transcript will be docketed.
6. The FAA will consider all materials presented at the meeting by
participants. Position papers and other handout material may be
accepted at the discretion of the chairperson. Participants are
requested to provide 10 copies of all materials to be presented, for
distribution to the panel members. Enough copies should be provided for
distribution to all conference participants.
7. Statements made by FAA participants at the meeting will not be
taken as expressing final FAA positions.
Issued in Renton, Washington, on April 5, 1996.
Ronald T. Wojnar,
Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 96-9250 Filed 4-12-96; 8:45 am]
BILLING CODE 4910-13-M
