[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