[Federal Register Volume 59, Number 200 (Tuesday, October 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-25691]


[[Page Unknown]]

[Federal Register: October 18, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-149-AD]

 

Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to McDonnell Douglas Model DC-9-80 
series airplanes. This proposal would require the replacement of 
certain suspect horizontal stabilizer primary trim motors. This 
proposal is prompted by an analysis which revealed that certain 
incorrectly manufactured motor shafts could fail prematurely and, in 
turn, cause the primary trim motor to fail. The actions specified by 
the proposed AD are intended to prevent such failures of the primary 
trim motor, which could ultimately result in reduced controllability of 
the airplane.

DATES: Comments must be received by December 13, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-149-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, P.O. Box 1771, Long Beach, 
California 90801-1771, Attention: Business Unit Manager, Technical 
Administrative support, Dept. L51, M.C. 2-98. This information may be 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington; or at FAA, Los Angeles Aircraft Certification 
Office, Transport Airplane Directorate, 3229 East Spring Street, Long 
Beach, California.

FOR FURTHER INFORMATION CONTACT: Walter Eierman, Aerospace Engineer, 
Systems & Equipment Branch, ANM-130L, Los Angeles Aircraft 
Certification Office, FAA, Transport Airplane Directorate, 3229 East 
Spring Street, Long Beach, California 90806-2425; telephone (310) 988-
5336; fax (310) 988-5210.

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 94-NM-149-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. 94-NM-149-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    McDonnell Douglas Corporation and a supplier of horizontal 
stabilizer primary trim motors recently conducted an analysis of the 
horizontal stabilizer primary trim motors installed on Model DC-9-80 
series airplanes. Results of this analysis have revealed a condition in 
the motor that could lead to its premature failure. This condition has 
been attributed to the omission of a hardening process (heat treatment) 
during the manufacture of a specific lot of motor output shafts. 
Without this hardening process, the defective output shafts may 
experience excessive wear, which could lead to failure of the shaft 
and, consequently, failure of the trim motor. A shaft failure in the 
primary trim motor could also result in the inability of the trim 
gearbox to transmit the input from the alternate trim motor. This 
condition, if not corrected, could result in the loss of all stabilizer 
trim and subsequent reduced controllability of the airplane. No 
failures have actually occurred in service, however.
    The FAA has reviewed and approved McDonnell Douglas MD-80 Alert 
Service Bulletin A27-342, dated August 4, 1994, which describes 
procedures for inspecting the horizontal stabilizer primary trim motor 
to determine if the motor is one having a suspect serial number, and 
replacing the suspect motors.
    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 require inspecting the horizontal stabilizer primary 
trim motor to determine if the motor is one having a suspect serial 
number, and replacing the suspect motors. The actions would be required 
to be accomplished in accordance with the service bulletin described 
previously.-
    There are approximately 26 Model DC-9-80 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 13 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately .5 work hour per airplane to accomplish the 
proposed actions, and that the average labor rate is $55 per work hour. 
Based on these figures, the total cost impact of the proposed 
inspection requirements of this AD on U.S. operators is estimated to be 
$357.50, or $27.50 per airplane. -
    Replacement of suspect motors would require 4.5 work hours to 
accomplish, at an average labor charge of $55 per work hour. Required 
replacement parts would be provided by Sundstrand Electric Power 
Systems (the manufacturer of the horizontal stabilizer primary trim 
motors) at no charge to operators. Based on these figures, the total 
cost impact of the proposed replacement requirements of this AD on U.S. 
operators is estimated to be $3,217.50, or $247.50 per airplane. -
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted. -
    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 94-NM-149-AD.

     -Applicability: Model DC-9-80 series airplanes; as listed in 
McDonnell Douglas MD-80 Alert Service Bulletin A27-342, dated August 
4, 1994; certificated in any category. -
    Compliance: Required as indicated, unless accomplished 
previously. -
    To prevent failure of the horizontal stabilizer primary trim 
motor, accomplish the following: -
    (a) Within 6 months after the effective date of this AD, conduct 
a visual inspection of the horizontal stabilizer primary trim motor 
to determine if the motor is identified with one of the suspect 
serial numbers listed in McDonnell Douglas MD-80 Alert Service 
Bulletin A27-342, dated August 4, 1994. Conduct this inspection in 
accordance with the procedures specified in that service bulletin. -
    (1) If the horizontal stabilizer primary trim motor is not 
identified with a suspect serial number, no further action is 
required by this AD. -
    (2) If the horizontal stabilizer primary trim motor is 
identified with a suspect serial number, prior to further flight, 
replace the motor in accordance with the service bulletin. -
    (b) 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: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

     -(c) 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 October 12, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-25691 Filed 10-17-94; 8:45 am]
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