[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