[Federal Register Volume 61, Number 190 (Monday, September 30, 1996)]
[Proposed Rules]
[Pages 51068-51070]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-24887]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-217-AD]
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: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to all McDonnell Douglas Model 
DC-9-80 series airplanes, Model MD-88 airplanes, and Model MD-90 
airplanes, that currently requires revising the Airplane Flight Manual 
(AFM) to include limitations and procedures to address situations in 
which the autopilot or autothrottle fails to disengage. That AD was 
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. This action would require an inspection of the 
autopilot and autothrottle engage switches located in the flight 
guidance control panel, and installation of improved switches. 
Accomplishment of these actions would terminate the previous 
requirement for the AFM revision. The actions specified by the proposed 
AD are intended to ensure that the autopilot and autothrottle disengage 
when commanded to do so by the flightcrew.

DATES: Comments must be received by November 8, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-217-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, 
Long Beach, California 90846, Attention: Technical Publications 
Business Administration, Department C1-L51 (2-60). This information may 
be examined at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-217-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 96-NM-217-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On June 3, 1996, the FAA issued AD 96-12-21, amendment 39-9664 (61 
FR 29007, June 7, 1996), applicable to all McDonnell Douglas Model DC-
9-80 series airplanes, Model MD-88 airplanes, and Model MD-90 
airplanes, to require revising the FAA-approved Airplane Flight Manual 
(AFM) to include limitations and procedures to address situations in 
which the autopilot or autothrottle fails to disengage. That AD was 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 requirements of that AD are intended to ensure 
the flight crew's ability to control the airplane manually if the 
autopilot or autothrottle function fails to disengage.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, Honeywell Incorporated (the 
manufacturer of the microswitches) has developed improved autopilot and 
autothrottle switches that will preclude

[[Page 51069]]

the previous problems encountered with these items. Use of these 
improved switches will ensure that the autopilot and autothrottle 
disengage when commanded to do so by the flightcrew.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas MD-80 Service 
Bulletin MD80-22-122, dated August 6, 1996 (for Model DC-9-80 series 
airplanes and Model MD-88 airplanes); and McDonnell Douglas Service 
Bulletin MD90-22-005, dated August 6, 1996 (for Model MD-90 airplanes). 
Both of these bulletins describe procedures for inspecting, replacing, 
and functional testing the autopilot and autothrottle engage switches 
located in the flight guidance control panel (FGCP). Use of the 
improved switches will minimize the possibility of switches remaining 
in the ``ON'' position and preventing disengagement of the autopilot 
and autothrottle. (Both service bulletins refer to Honeywell Service 
Bulletin 4034242-22-13 for additional service instructions.)
    The improved switches have been installed during production on 
Model DC-9-80 series airplanes and Model MD-88 airplanes having 
manufacturer's fuselage numbers 1326, 2145, and subsequent. They also 
have been installed during production on Model MD-90 series airplanes 
having manufacturer's fuselage numbers 2018, 2138, and subsequent.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 96-12-21 to require an inspection of the 
autopilot and autothrottle engage switches in the FGCP, and replacement 
of the switches with improved switches. The actions would be required 
to be accomplished in accordance with the service bulletin described 
previously.
    The installation of the improved switches would constitute 
terminating action for the AFM revision previously required by AD 96-
12-21. Once the switches are installed, that revision may be removed 
from the AFM.

Cost Impact

    There are approximately 970 Model DC-9-80 series airplanes, Model 
MD-88 airplanes, and Model MD-90 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 512 airplanes of U.S. 
registry would be affected by this proposed AD.
    The AFM revision that is currently required by AD 96-12-21 takes 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact on U.S. operators of the actions currently required is estimated 
to be $30,720, or $60 per airplane.
    The new actions that are proposed in this AD action would take 
approximately 1.5 work hours per airplane to accomplish (this figure 
includes inspection, removal, installation, and a functional check), at 
an average labor rate of $60 per work hour. Required parts would be 
provided by the manufacturer at no charge to operators. Based on these 
figures, the cost impact on U.S. operators of the proposed requirements 
of this AD is estimated to be $46,080, or $90 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, will not have a significant economic impact, 
positive or negative, on a substantial number of small entities under 
the criteria of the Regulatory Flexibility Act. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 removing amendment 39-9664 (61 FR 
29007, June 7, 1996), and by adding a new airworthiness directive (AD), 
to read as follows:

McDonnell Douglas: Docket 96-NM-217-AD. Supersedes AD 96-12-21, 
Amendment 39-9664.

    Applicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 
(MD-83), DC-9-87 (MD-87), and Model MD-88 airplanes, as listed in 
McDonnell Douglas Service Bulletin MD80-22-122, dated August 6, 
1996; and Model MD-90 airplanes, as listed in McDonnell Douglas 
Service Bulletin MD90-22-005, dated August 6, 1996; certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (d) 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 June 24, 1996 (the effective date of AD 
96-12-21, amendment 39-9664), 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 June 24, 1996 (the effective date of AD 
96-12-21, amendment 39-9664), revise the Abnormal Procedures

[[Page 51070]]

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) Within 120 days after the effective date of this AD, 
accomplish the inspection and replacement of the autopilot and 
autothrottle engage switches in the flight guidance control panel 
(FGCP), in accordance with the paragraphs 3., 3.A., and 3.B. of the 
Accomplishment Instructions of McDonnell Douglas Service Bulletin 
MD80-22-122, dated August 6, 1996 (for Model DC-9-80 series 
airplanes and Model MD-88 airplanes); and McDonnell Douglas Service 
Bulletin MD90-22-005, dated August 6, 1996 (for Model MD-90 
airplanes). Once these actions are completed, the AFM revision 
required by paragraphs (a) and (b) of this AD may be removed.

    Note 2: The McDonnell Douglas service bulletins referenced in 
this paragraph refer to Honeywell Incorporated Service Bulletin 
4034242-22-13 for additional service instructions.

    (d) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (e) 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.

    Issued in Renton, Washington, on September 23, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-24887 Filed 9-27-96; 8:45 am]
BILLING CODE 4910-13-U