[Federal Register Volume 61, Number 209 (Monday, October 28, 1996)]
[Notices]
[Pages 55682-55684]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27616]
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DEPARTMENT OF TRANSPORTATION
Notice of Public Meeting
AGENCY: Federal Aviation Administration (FAA), DOT.
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 the criteria used in
showing compliance with Sec. 25.671(c)(3) of the Federal Aviation
Regulations (FAR) relative to jammed flight control systems. Interested
parties are invited to make presentations or submit material for the
record.
DATES: The public meeting is scheduled for Tuesday, December 3, 1996.
On-site registration will begin at 7:30 a.m., and the public meeting
will begin at 8:30 a.m.
REGISTRATION: Persons planning to attend the public meeting should pre-
register by contacting the person identified later in this notice as
the contact for further information. Arrangements for oral
presentations must be made by November 1, 1996.
ADDRESSES: The public meeting will be held at the Holiday Inn Sea-Tac
International Airport, 17338 International Blvd., Seattle, WA 98188.
Telephone: 206-248-1000, Fax: 206-242-7089. Hotel room reservations
should be made in advance. A block of rooms has been reserved at the
Holiday Inn Sea-Tac International Airport. The room rate is $74 plus
tax. Persons wishing to attend the public meeting are encouraged to
make reservations by November 15, 1996, by contacting the hotel direct
at 206-248-1000. Be sure to identify yourself as an attendee of the
``FAA public meeting on jammed flight controls'' to receive the special
rate.
FOR FURTHER INFORMATION CONTACT:
Iven Connally, FAA, Transport Standards Staff, Transport Airplane
Directorate, 1601 Lind Avenue SW., Renton, WA 98055-4056; telephone
(206) 227-2120.
SUPPLEMENTARY INFORMATION: Notice is herewith given of a public meeting
to be held on Tuesday, December 3, 1996, at the Holiday Inn Sea-Tac
International Airport. The purpose of this meeting is to hear comments
from the general public regarding criteria to be used in showing
compliance with the requirements of Sec. 25.671(c)(3) relative to the
flight control jams in the ``normally encountered'' position. The FAA
is inviting the interested public to participate in developing
standardized methods to be used in showing compliance with this
requirement. The FAA will consider information presented at the public
meeting in the course of developing future advisory material on this
subject. In addition, the public is invited to discuss the National
Transportation Safety Board (NTSB) Recommendation A-96-108. It
recommends that 14 CFR 25.671 be revised to account for failure or
jamming of any flight control surface at its design-limited deflection.
The FAA will consider any public comments on this recommendation in
developing a response to the NTSB.
The agenda for the meeting will include:
Regulatory Background
Certification Procedures
Presentations from the Public
In order to expedite the resolution of this issue, the FAA has
developed an initial certification policy on this subject, which is
presented in this notice. The public is invited to comment on any
aspect of the draft policy. In addition to the general discussion on
jams in the flight controls, the FAA is soliciting data on control
surface deflection exceedances per flight hour based on normal revenue
flights. For convenience, this data should be presented in the form of
a plot of control surface deflection in degrees vs. number of
exceedances per flight hour. These data are needed to determine the
surface deflections normally encountered during all phases of flight.
The FAA Proposed Policy
In the absence of more rational data, the criteria listed below
should be used to define the jammed control surface positions. The
control surface deflections associated with the ``Conditions at the
time of the Control Surface Jam'' must be based on the maximum
deflections developed during initiation of and recovery from the
maneuver. In order to account for the probability of occurrence of the
jam, the maneuver and gust conditions at the time of the jam should be
selected at the once in one hundred hours exceedance level. The
exceedance data should be obtained from normal revenue flights.
[[Page 55683]]
Controllability must be evaluated in the jammed condition for all
approved airplane gross weights and center of gravity (c.g.) locations.
However, only critical combinations of gross weights and c.g. locations
need to be demonstrated.
Alternate means of control, such as trim systems, may be used if it
can be demonstrated that the systems are available and sufficiently
responsive to allow the pilot to control the airplane. No credit will
be given for differential engine thrust in maneuvering the airplane.
For the purpose of establishing control positions normally encountered,
only the airplane rigid body modes need to be considered when
evaluating the airplane response to either maneuvers or gusts. The
combined effects of pilot input and any automatic system response (with
system both on and off) must be evaluated for these conditions. It is
not necessary to consider additional failures (e.g., engine failure)
when evaluating the jammed condition.
The controllability criteria typically applied in satisfying these
requirements use the FAA Handling Qualities Rating Method (HQRM)
(Reference Appendix 7 of the draft revision to AC 25-7, as announced in
the Federal Register, 61 FR 14847, dated April 3, 1996) as an
evaluation tool, and specify the minimum handling qualities rating
necessary to show compliance with the regulation.
Conditions at Time of the Control Surface Jam
Jammed Elevator Positions
Takeoff run (elevator for airplane nose down appropriate for the
airplane).
Takeoff rotation (at maximum elevator for airplane nose up
rotation).
Normal maneuvers between 0.8 and 1.3gs anywhere between V2/
Vref and Vmo.
Vertical discrete gusts up to 25 fps from S.L. to 20,000 feet.
Jammed Rudder Positions
Limit of the yaw damper control authority.
One third of the total available travel of the control surface.
Lateral discrete gusts up to 25 fps from S.L. to 20,000 feet.
Steady crosswinds up to 20 knots in the takeoff and landing
configuration.
Jammed Aileron and Roll Control Spoiler Positions
One third of the total available travel of the control surface up
to 250 knots. For speeds above 250 knots, the deflection associated
with the roll rate established at 250 knots.
Vertical and lateral discrete gusts up to 25 fps from S.L. to
20,000 feet Servo tabs installed on control surfaces are assumed jammed
in the position associated with the deflection of the control surface
on which they are installed. For example, the aileron servo tax
positions are those associated with the aileron positions at the time
of the jam described herein. Servo tabs are tabs that are designed to
assist in moving the control service.
Trim tabs and movable stabilizers are assumed jammed in the
position normally selected for takeoff, landing, and normally used
throughout the flight to maintain the airplane in the trimmed
conditions for all gross weights and c.g. locations.
Speed brake panels are assumed to jam in any position for which
they are approved to operate during flight that might result from any
condition of failure in the system not shown to be extremely
improbable.
Flaps and slats are assumed to jam in any position used for
takeoff, approach, and landing, as well as in the fully retracted
position, that might result from any failure condition in the system
not shown to be extremely improbable. Section 25.701 addresses the
asymmetrical jam conditions for which these devices must be designed.
Critical for Continued Safe Flight and Landing Following a Jam
The airplane must have sufficient maneuverability and residual
structural strength for continued safe flight and landing after jams in
the flight controls. Consideration may be given to any appropriate
reconfiguration and flight limitations following the jam. The FAA
handling qualities rating method will be used to evaluate airplane
handling characteristics. Controllability following a jam must be
demonstrated by flight test or a validated flight simulator. The
following criteria must be used to evaluate the handling qualities
following a control jam:
(1) The transient condition should be rated at least CONTROLLABLE
(CON).
(2) For continued safe flight and landing with the jammed
condition, the airplane should have sufficient remaining control
authority, and the FAA Handling Qualities Rating should not be less
than ADEQUATE (ADQ), including:
Short and long term control forces must meet the criteria
of Sec. 25.143(c).
The airplane must be maneuverable to the NFE boundaries
for angle-of-attack, load factor, and bank angle.
There must be sufficient remaining control authority to
land in an adverse 10 knot crosswind.
Airplane flight manual procedures for jams may assume that crews
share the flying duties, provided these procedures are clearly
described and can be consistently executed in service by pilots of
average skill (ref. Sec. 25.101(h)). All jammed-control procedures
should be covered in crew training, and in qualification checks as
appropriate.
The ultimate structural strength requirements necessary for
continued safe flight with the control surface in the jammed position
must not be less than that necessary to;
(1) Maneuver the airplane between 0.25 and 1.75gs with flaps up,
and 0.6 and 1.4gs with flaps down.
(2) Withstand vertical and lateral discrete gusts to 40 percent of
limit gust velocity.
Note: If a rational balanced maneuver can not be achieved at the
specified load factors with the jam condition, then a safety factor
of 1.35 may be applied to the loads developed at the highest load
factors attainable but need not exceed the load factors specified
above.
Requests To Be Heard
Attendance is open to the interested public, but will be limited to
the space available. Persons planning to present data or comments at
the public meeting are requested to provide the FAA an abstract of
their presentation by November 15, 1996. The abstract should include an
estimate of the time needed to make the presentation, and should be
mailed to the person identified earlier in this notice as the contact
for further information. 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. Following each presentation, a
discussion period will be allowed and all persons will be given the
opportunity to open discussions on the presentation.
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. It will be necessary to adhere to the meeting
schedule in order to enable adjournment within the time allowed.
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.
[[Page 55684]]
3. Representatives of the FAA will preside over the meeting. A
panel of FAA personnel involved in this issue will be present.
4. The meeting will be recorded by a court reporter. Anyone
interested in purchasing the transcript should contact the court
reporter directly. A copy of the court reporter's transcript will be
placed in the docket.
5. 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. Enough copies should be
provided for distribution to all conference participants.
6. Statements made by FAA participants at the meeting may not
reflect the final FAA positions.
Issued in Renton, Washington, on October 21, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 96-27616 Filed 10-25-96; 8:45 am]
BILLING CODE 4910-13-M
