[Federal Register Volume 61, Number 111 (Friday, June 7, 1996)]
[Rules and Regulations]
[Pages 29006-29008]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-14385]
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[[Page 29007]]
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-111-AD; Amendment 39-9664; AD 96-12-21]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series
Airplanes, Model MD-88 Airplanes, and Model MD-90 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to all McDonnell Douglas Model DC-9-80 series airplanes,
Model MD-88 airplanes, and Model MD-90 airplanes. This action requires
revising the Airplane Flight Manual to include limitations and
procedures to address situations in which the autopilot or autothrottle
fails to disengage. This amendment is prompted by incidents in which
the flightcrew was unable to disconnect the autopilot or autothrottle
function from the engaged position, due to a discrepancy in a
microswitch that is associated with the operation of those functions.
The actions specified in this AD are intended to ensure the flight
crew's ability to control the airplane manually if the autopilot or
autothrottle function fails to disengage.
DATES: Effective June 24, 1996.
Comments for inclusion in the Rules Docket must be received on or
before August 6, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-111-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
Information concerning this rulemaking action may be examined at
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington; or at the FAA, Los Angeles Aircraft Certification Office,
Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood,
California.
FOR FURTHER INFORMATION CONTACT: J. Kirk Baker, Aerospace Engineer,
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft
Certification Office, 3960 Paramount Boulevard, Lakewood, California
90712; telephone (310) 627-5345; fax (310) 627-5210.
SUPPLEMENTARY INFORMATION: The FAA has received several reports of
incidents in which either the autopilot or the autothrottle function on
McDonnell Douglas Model DC-9-80 series airplanes failed to disconnect
from the engaged position. Two incidents occurred in which the flight
crew was unable to disengage the autopilot function. As a result of one
of these incidents, which occurred when the airplane was on final
approach, the flight crew found it necessary to declare an emergency
and to perform a go-around. At least two other incidents occurred in
which the flight crew was unable to disengage the autothrottle
function.
Investigation of these incidents revealed that the toggle/cam
assembly of a microswitch, which is used for the autopilot and
autothrottle functions on the Digital Flight Guidance Control Panel
(DFGCP), can fail the functions in the engaged position. Further
investigation revealed that the flight crew was able to disengage the
autopilot or authrottle function by depressing and holding the release
button for the functions (which are located on the control column and
throttle levers). However, once the release button was released, the
function re-engaged.
Failure of the autopilot or autothrottle function to disconnect
from the engaged position can adversely affect the flight crew's
ability to control the airplane manually.
Since the toggle/cam assembly of the subject microswitch that is
installed on Model DC-9-80 series airplanes may also be installed on
Model MD-88 and MD-90 airplanes, all of these airplane models may be
subject to this same unsafe condition.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other Model DC-9-80 series, Model MD-88, and Model
MD-90 airplanes of the same type design, this AD is being issued to
ensure the flight crew's ability to continue to control the airplane
manually if the autopilot or autothrottle function fails to disengage.
This AD requires a revision to the FAA-approved Airplane Flight Manual
(AFM) to include limitations and procedures to address situations in
which the autopilot or autothrottle fails to disengage.
The FAA points out that failure of the autopilot or autothrottle
function to disconnect from the engaged position can occur during any
phase of flight. If it occurs during cruise, the flight crew can
readily address the situation and continue to fly the airplane manually
with the autopilot or autothrottle engaged. However, a safety concern
arises if the failure occurs during approach, when the flight crews
workload is particularly heavy and the airplane is close to the ground;
the optimal environment for the flight crew during approach is one that
is free from distraction. The limitation and associated abnormal
procedures that are required by this AD to be included in the AFM will
ensure that the flight crew is briefed on the appropriate procedures
and, thereby, will be less distracted during that critical phase of
flight.
The requirements of this AD are considered to be interim action
until final action is identified, at which time the FAA may consider
additional rulemaking.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications shall identify the Rules Docket number and be submitted
in triplicate to the address specified under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped
[[Page 29008]]
postcard on which the following statement is made: ``Comments to Docket
Number 96-NM-111-AD.'' The postcard will be date stamped and returned
to the commenter.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, may be obtained from the Rules Docket at the
location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-12-21 McDonnell Douglas: Amendment 39-9664. Docket 96-NM-111-AD.
Applicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83
(MD-83), DC-9-87 (MD-87), MD-88, and MD-90 airplanes; certificated
in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (c) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To ensure the flight crew's ability to continue to control the
airplane manually if the autopilot or autothrottle function fails to
disengage, accomplish the following:
(a) Within 14 days after the effective date of this AD, revise
the Limitations section of the FAA-approved Airplane Flight Manual
(AFM) to include the following statement. This may be accomplished
by inserting a copy of this AD in the AFM.
``If the autopilot or autothrottle fails to disconnect normally,
press and hold the autopilot release button or either autothrottle
release button, as appropriate. Refer to the Abnormal Procedures
section for procedures if the autopilot or autothrottle fails to
disconnect.''
(b) Within 14 days after the effective date of this AD, revise
the Abnormal Procedures section of the FAA-approved AFM to include
the following information. This may be accomplished by inserting a
copy of this AD in the AFM.
``AUTOPILOT:
If the Autopilot (A/P) disconnects when the AUTOPILOT RELEASE
button on either control wheel is depressed, and re-engages when the
AUTOPILOT RELEASE button is released, accomplish the following
procedures:
PROCEDURE: Use Autopilot (as desired)
AUTOPILOT RELEASE button--PRESS AND HOLD
Hold either yoke (yellow) Autopilot Release button
while continuing to fly the aircraft manually. The A/P will remain
disengaged while depressing the button.
When the Autopilot Release button is released, the A/P
will engage and all A/P functions should work normally.
TO SILENCE THE AURAL WARNING:
CAWS C/B (P-38)--PULL
Circuit breaker is located behind the Captain's seat.
Pulling the C/B will disable the Stall Warning SSRS-1,
Landing Gear, Takeoff, Cabin Altitude, Speed Brake aural warnings,
in addition to the Autopilot aural warning.
CAUTION:
Do not attempt to overpower the autopilot. When the autopilot is
engaged, applying force to the column may allow the alternate trim
to reposition the stabilizer. If the force is applied long enough,
it will result in an out-of-trim condition.''
``AUTOTHROTTLE:
If the Autothrottle (A/T) disconnects when either throttle
disconnect button is depressed, and re-engages when throttle
disconnect button is released, accomplish the following procedures:
PROCEDURE: Use Autothrottle System (as desired)
WHEN A DISCONNECT IS NECESSARY:
AUTOTHROTTLE RELEASE BUTTON--PRESS AND HOLD
Press and hold either button until flashing red A/T
annunciation is illuminated. Flashing red light indicates
autothrottle is disconnected.
AUTOTHROTTLE RELEASE BUTTON may then be released.
The FMA A/T window will annunciate as though the A/T is
engaged.
The flashing red A/T annunciation of the FMA cannot be
extinguished with repeated depression of the autothrottle release
button.
If the throttle levers are retarded to the idle stop,
the flashing red A/T annunciation will extinguish, and the A/T
system will re-engage.
If the DFGC is selected to the IAS mode and the A/T
SPEED mode is selected, the A/T system will re-engage.''
(c) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Los Angeles Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Los Angeles ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(d) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(e) This amendment becomes effective on June 24, 1996.
Issued in Renton, Washington, on June 3, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-14385 Filed 6-06-96; 8:45 am]
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