[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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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

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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
    <bullet> Hold either yoke (yellow) Autopilot Release button 
while continuing to fly the aircraft manually. The A/P will remain 
disengaged while depressing the button.
    <bullet> 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
    <bullet> Circuit breaker is located behind the Captain's seat.
    <bullet> 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
    <bullet> Press and hold either button until flashing red A/T 
annunciation is illuminated. Flashing red light indicates 
autothrottle is disconnected.
    <bullet> AUTOTHROTTLE RELEASE BUTTON may then be released.
    <bullet> The FMA A/T window will annunciate as though the A/T is 
engaged.
    <bullet> The flashing red A/T annunciation of the FMA cannot be 
extinguished with repeated depression of the autothrottle release 
button.
    <bullet> 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.
    <bullet> 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]
BILLING CODE 4910-13-P