[Federal Register Volume 61, Number 18 (Friday, January 26, 1996)]
[Rules and Regulations]
[Pages 2407-2409]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-475]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-91-AD; Amendment 39-9485; AD 96-01-09]


Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series 
Airplanes and Model MD-88 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain McDonnell Douglas Model DC-9-80 series airplanes 
and Model MD-88 airplanes, that requires installation of hydraulic line 
restrictors in the main landing gear (MLG), and modification of the 
hydraulic damper assembly of the MLG. This amendment is prompted by 
reports of vibration occurring in the MLG during landing; in some 
cases, such vibration has led to the collapse of the MLG. The actions 
specified by this AD are intended to prevent incidents of vibration in 
the MLG, which can adversely affect the integrity of the MLG.

DATES: Effective February 26, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 26, 1996.

ADDRESSES: The service information referenced in this AD 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 Federal Aviation Administration (FAA), Transport 
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Los Angeles Aircraft Certification Office, 
Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood, 
California; or at the Office of the Federal Register, 800 North Capitol 
Street NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Walter Eierman, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft 
Certification Office, 3960 Paramount Boulevard, Lakewood, California 
90712; telephone (310) 627-5336; fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
DC-9-80 series airplanes and Model MD-88 airplanes was published in the 
Federal Register on September 26, 1995 (60 FR 49523). That action 
proposed to require installation of hydraulic line restrictors in the 
main landing gear (MLG), and modification of the hydraulic damper 
assembly of the MLG.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    Four commenters support the proposal.
    One commenter requests that the FAA revise the proposal to include 
references to later revisions of the pertinent service bulletins, which 
were recently released. The FAA concurs. Subsequent to the issuance of 
the proposal, the FAA reviewed and approved Revision 1 of McDonnell 
Douglas MD-80 Service Bulletin MD80-32-276, dated October 17, 1995; and 
Revision 1 of McDonnell Douglas MD-80 Service Bulletin MD80-32-278, 
dated September 6, 1995. These revisions are essentially identical to 
the original issues of the service bulletins (which were referenced in 
the proposal), but contain additional clarifying information. 
Additionally, the FAA has reviewed and approved McDonnell Douglas MD-80 
Alert Service Bulletin MD80-A32-286, dated September 11, 1995, which 
contains, among other things, instructions for installing filtered 
restrictors in the MLG hydraulic brake system. The FAA has revised the 
final rule to include these newly released service bulletins as 
additional sources of appropriate service instructions.
    One commenter requests that paragraph (a) of the proposal be 
revised to extend the compliance time for installation of the brake 
line restrictors. This commenter is concerned that an ample number of 
required parts will not be available to modify its large fleet within 
the proposed compliance time of 9 months. The FAA does not concur that 
an extension of the compliance time is necessary. In McDonnell Douglas 
MD-80 Service Bulletin MD80-32-276, the manufacturer recommended that 
the installation of the restrictors be accomplished on the affected 
fleet within 12 months. Since the latest revision of that service 
bulletin was issued on October 17, 1995, the FAA considers it to be 
substantiation that the manufacturer can support parts production and 
delivery for the affected fleet through October 17, 1996. Since 
compliance with this AD is required by approximately that same date, 
the FAA does not foresee that the availability of required parts will 
be a problem for operators. However, under the provisions of paragraph 
(c) of the final rule, the FAA may approve requests for adjustments to 
the compliance time if data are submitted to substantiate that such an 
adjustment would provide an acceptable level of safety.
    One commenter requests that the FAA defer action on the proposed 
requirements of paragraph (b), which would require operators to modify 
the hydraulic damper assembly. This commenter contends that further 
research and testing of the structural integrity of the reservoir 
should be accomplished first to substantiate that the installation of 
the hydraulic brake line restrictors [that would be required by 
paragraph (a) of the proposal] will successfully curb the vibration 
problems. This commenter claims that, if the most vulnerable part of 
the damper design is the reservoir, then no amount of ``efficiency 
improvements'' to the basic damper assembly will help. 

[[Page 2408]]
The FAA does not concur with the commenter's request. The FAA finds 
that the previous evaluations of this problem confirm that the 
reservoir failures are the result of the landing gear vibration, and 
are not a preceding failure that contributes to the vibration. Based on 
these evaluations and other data obtained to date, the FAA maintains 
that the modification required by paragraph (b) is both warranted and 
appropriate.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 1,100 Model DC-9-80 series airplanes and 
Model MD-88 airplanes of the affected design in the worldwide fleet. 
The FAA estimates that 600 airplanes of U.S. registry will be affected 
by this proposed AD.
    Accomplishment of the installation of the brake line restrictor, as 
described in McDonnell Douglas MD-80 Service Bulletin MD80-32-276, will 
take approximately 4 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Required parts will cost 
approximately $928 per airplane. Based on these figures, the cost 
impact of this installation on U.S. operators is estimated to be 
$700,800, or $1,168 per airplane.
    Accomplishment of the modification of the hydraulic damper 
assembly, as described in McDonnell Douglas MD-80 Service Bulletin 
MD80-32-278, will take approximately 6 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts will cost approximately $4,000 per airplane. Based on these 
figures, the cost impact of this modification on U.S. operators is 
estimated to be $2,616,000, or $4,360 per airplane.
    Based on the figures discussed above, the FAA estimates that the 
cost impact of this AD on U.S. operators would be approximately 
$3,316,800, or $5,528 per airplane. This cost impact figure is based on 
assumptions that no operator has yet accomplished any of the 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    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.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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, Incorporation by 
reference, 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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

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

96-01-09  McDonnell Douglas: Amendment 39-9485. Docket 95-NM-91-AD.

    Applicability: Model DC-9-81 (MD-81), -82 (MD-82), -83 (MD-83), 
and -87 (MD-87) series airplanes, and Model MD-88 airplanes; 
certificated in any category; and listed in the following McDonnell 
Douglas Service Bulletins:
     McDonnell Douglas MD-80 Service Bulletin MD80-32-276, 
dated March 31, 1995; and
     McDonnell Douglas MD-80 Service Bulletin MD80-32-278, 
dated March 31, 1995.

    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 use the authority 
provided in paragraph (c) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.
    Compliance: Required as indicated, unless accomplished 
previously.
    To reduce the possibility of vibration in the main landing gear 
(MLG) that can adversely affect its integrity, accomplish the 
following:
    (a) For airplanes listed in McDonnell Douglas MD-80 Service 
Bulletin MD80-32-276, dated March 31, 1995, that have not been 
previously modified (installation of brake line restrictors) in 
accordance with McDonnell Douglas MD-80 Service Bulletin 32-246: 
Within 9 months after the effective date of this AD, install 
filtered brake line restrictors in the MLG hydraulic brake system in 
accordance with McDonnell Douglas MD-80 Service Bulletin MD80-32-
276, dated March 31, 1995, or Revision 1, dated October 17, 1995.

    Note 2: Installation of the filtered restrictors in accordance 
with the instructions contained in McDonnell Douglas MD-80 Alert 
Service Bulletin MD80-A32-286, dated September 11, 1995, is 
considered acceptable for compliance with paragraph (a) of this AD.

    (b) For airplanes listed in McDonnell Douglas MD-80 Service 
Bulletin MD80-32-278, dated March 31, 1995: Within 36 months after 
the effective date of this AD, modify the hydraulic damper assembly 
(by removing shims, increasing bolt torque, and incorporating 
changes to increase the volume of fluid passing between the two 
damper chambers) in accordance with McDonnell Douglas MD-80 Service 
Bulletin MD80-32-278, dated March 31, 1995, or Revision 1, dated 
September 6, 1995.
    (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 3: 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.

[[Page 2409]]

    (e) The installation shall be done in accordance with McDonnell 
Douglas MD-80 Service Bulletin MD80-32-276, dated March 31, 1995; or 
McDonnell Douglas MD-80 Service Bulletin MD80-32-276, Revision 1, 
dated October 17, 1995. The modification shall be done in accordance 
with McDonnell Douglas MD-80 Service Bulletin MD80-32-278, dated 
March 31, 1995; or McDonnell Douglas MD-80 Service Bulletin MD80-32-
278, Revision 1, dated September 6, 1995. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from McDonnell Douglas Corporation, 3855 Lakewood 
Boulevard, Long Beach, California 90846, Attention: Technical 
Publications Business Administration, Department C1-L51 (2-60). 
Copies may be inspected 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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.
    (f) This amendment becomes effective on February 26, 1996.

    Issued in Renton, Washington, on January 5, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-475 Filed 1-25-96; 8:45 am]
BILLING CODE 4910-13-P