[Federal Register Volume 63, Number 203 (Wednesday, October 21, 1998)]
[Proposed Rules]
[Pages 56125-56127]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-28155]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-269-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model MD-90-30 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 certain McDonnell Douglas Model 
MD-90-30 series airplanes. This proposal would require modification of 
the right and left main landing gear (MLG) hydraulic damper assemblies 
or replacement of the MLG hydraulic damper assemblies with modified and 
reidentified hydraulic damper assemblies. This proposal is prompted by 
reports indicating that, during overhauls, the MLG hydraulic dampers 
assemblies failed or had damaged spring retainers due to insufficient 
material thickness of the spring retainers. The actions specified by 
the proposed AD are intended to prevent failure of the hydraulic damper 
assemblies of the MLG, which could result in vibration damage and 
collapse of the MLG.

DATES: Comments must be received by December 7, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-269-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 The Boeing Company, Douglas Products Division, 3855 
Lakewood Boulevard, Long Beach, California 90846, Attention: Technical 
Publications Business Administration, Dept. C1-L51 (2-60). This 
information may be examined at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington or at the FAA, Transport 
Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 
Paramount Boulevard, Lakewood, California.


[[Page 56126]]


FOR FURTHER INFORMATION CONTACT: Walter Eierman, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount 
Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5336; 
fax (562) 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 98-NM-269-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-114, Attention: Rules 
Docket No. 98-NM-269-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that, during overhauls, 30 
percent of the latest configuration of the main landing gear (MLG) 
hydraulic damper assemblies installed on McDonnell Douglas Model MD-90 
series airplanes failed or had damaged spring retainers. Investigation 
revealed that the cause of the hydraulic damper assemblies failures or 
damaged spring retainers may be insufficient material thickness of the 
spring retainers. Such failure of the spring retainers, if not 
corrected, could result in failure of the hydraulic damper assemblies 
of the MLG, which could result in vibration damage and collapse of the 
MLG.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin MD90-32-032, dated July 8, 1998, which describes procedures 
for modification of the right and left MLG hydraulic damper assemblies. 
The modification involves removal and disassemblage of the hydraulic 
damper assemblies; installation of new spring retainers in the damper 
assemblies; and installation of the modified and reidentified hydraulic 
damper assemblies. Accomplishment of the actions specified in the 
service bulletin is intended to adequately address the identified 
unsafe condition.

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 require modification of the hydraulic damper 
assemblies or replacement of the hydraulic damper assemblies with 
modified and reidentified hydraulic damper assemblies.

Cost Impact

    There are approximately 111 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 40 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 18 work hours per airplane (including 
access, removal, and closeup) to accomplish the proposed modification, 
at an average labor rate of $60 per work hour. Required parts would 
cost approximately $598 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be $1,678 
per airplane.
    It would take approximately 5 work hours per airplane to accomplish 
the proposed replacement at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the replacement proposed by 
this AD on U.S. operators is estimated to be $300 per airplane.
    The cost impact figures discussed above are 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.

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 adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 98-NM-269-AD.

    Applicability: Model MD-90-30 series airplanes, as listed in 
McDonnell Douglas Service Bulletin MD90-32-032, dated July 8, 1998; 
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

[[Page 56127]]

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 prevent failure of the hydraulic damper assemblies of the 
main landing gear (MLG), which could result in vibration damage and 
collapse of the MLG, accomplish the following:
    (a) Within 2 years after the effective date of this AD, 
accomplish the requirements specified in either paragraph (a)(1) or 
(a)(2) of this AD.
    (1) Modify the right and left MLG hydraulic damper assemblies in 
accordance with McDonnell Douglas Service Bulletin MD90-32-032, 
dated July 8, 1998; or
    (2) Replace the right and left MLG hydraulic damper assemblies 
with modified and reidentified hydraulic damper assemblies having 
part number (P/N) SR09320057-7005, SR09320057-7007, SR09320057-7009, 
or 5923142-5513, in accordance with paragraph B.5. of the 
Accomplishment Instructions of the service bulletin.
    (b) As of the effective date of this AD, no person shall install 
on any airplane a damper sub assembly having P/N SR09320057-9, 
SR09320057-17, or 5923142-5017; or a damper assembly having P/N 
SR09320057-7001, SR09320057-7003, or 5923142-5511, unless the part 
is modified in accordance with paragraph (a)(1) of this AD.
    (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.

    Issued in Renton, Washington, on October 14, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-28155 Filed 10-20-98; 8:45 am]
BILLING CODE 4910-13-U