[Federal Register Volume 61, Number 198 (Thursday, October 10, 1996)]
[Rules and Regulations]
[Pages 53042-53044]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-25576]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-91-AD; Amendment 39-9777; AD 96-21-01]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, -
30, -40, and -50 Series Airplanes and C-9 (Military) 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 series airplanes,
that requires either replacement or modification of the hydraulic
damper assembly. This amendment is prompted by reports indicating that
insufficient damping of the hydraulic shimmy damper in the main landing
gear (MLG) can allow high torsional vibration to occur. The actions
specified by this AD are intended to prevent such vibration, which can
damage the MLG assembly and lead to its collapse.
DATES: Effective November 14, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director
[[Page 53043]]
of the Federal Register as of November 14, 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, Transport Airplane Directorate, Los Angeles
Aircraft Certification Office, 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 series airplanes and C-9 (military) airplanes was published in the
Federal Register on July 10, 1996 (61 FR 36307). That action proposed
to require either replacing or modifying the hydraulic damper assembly.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Support for the Proposal
Four commenters support the proposal.
Request to Withdraw Proposal
One commenter contends that all reports of torsional vibration that
resulted in torque link separations and/or breakage of the apex bolt
occurred on Model DC-9-80 series airplanes. Given the number of Model
DC-9 series airplanes in service and the number of landings logged on
them without reports of torsional vibration caused by insufficient
damping, the commenter considers the AD to be unwarranted. Further,
this commenter states that the modification should not be mandated;
operators should be allowed to accomplish it at their own discretion
during a regularly scheduled maintenance visit.
From these comments submitted, the FAA infers that the commenter
requests that the proposed rule be withdrawn; in which case, the FAA
does not concur. The commenter is incorrect in stating that the
problems associated with torsional vibration have occurred only on
Model DC-9-80 series airplanes. Such incidents and consequent damage
have occurred on several Model DC-9 series airplanes as well. As
detailed in the preamble to the notice, the MLG torque link broke on
one airplane and, on another airplane, the nut was stripped off of the
torque link apex bolt; both of these discrepancies were the result of
insufficient damping of the MLG hydraulic shimmy damper. This fact
alone affirms the need for this AD action.
As for mandating the modification, the FAA points out that this AD
provides operators with the option of either modifying the damper
assembly or replacing it with an improved assembly. The compliance time
of 24 months assures that operators will be able to schedule the
accomplishment of either of these actions during a normal maintenance
interval.
Conclusion
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 as proposed.
Cost Impact
There are approximately 878 Model DC-9 series airplanes and C-9
(military) airplanes of the affected design in the worldwide fleet. The
FAA estimates that 590 airplanes of U.S. registry will be affected by
this AD.
To accomplish the replacement will take approximately 5.9 work
hours per airplane, at an average labor rate of $60 per work hour.
Required parts will cost approximately $11,139 per airplane (two
assemblies at $5,569 each). Based on these figures, the cost impact of
the replacement action on U.S. operators is estimated to be $11,492 per
airplane.
To accomplish the required modification will take approximately
10.9 work hours per airplane, at an average labor rate of $60 per work
hour. Required parts will cost approximately $2,907 per airplane. Based
on these figures, the cost impact of the modification action on U.S.
operators is estimated to be $3,561 per airplane.
Based on the figures discussed above, the cost impact of this AD on
the U.S. fleet is between $2,100,990 and $6,780,280. These cost impact
figures are 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.
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.
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 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-21-01 McDonnell Douglas: Amendment 39-9777. Docket 96-NM-91-AD.
Applicability: Model DC-9-10, -20, -30, -40, and -50 series
airplanes, and C-9 (military) airplanes; as listed in McDonnell
Douglas Service Bulletin DC9-32-289, dated March 7, 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
[[Page 53044]]
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 (b) 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 high torsional vibration from occurring, which can
damage the main landing gear (MLG) assembly and lead to its
collapse, accomplish the following:
(a) Within 24 months after the effective date of this AD, either
replace or modify the MLG hydraulic damper assembly, in accordance
with the procedures specified as either ``Option 1'' or ``Option
2,'' respectively, in McDonnell Douglas Service Bulletin DC9-32-289,
dated March 7, 1996.
(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 2: 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.
(d) The actions shall be done in accordance with McDonnell
Douglas Service Bulletin DC9-32-289, dated March 7, 1996. 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, Transport Airplane Directorate, Los Angeles Aircraft
Certification Office, 3960 Paramount Boulevard, Lakewood,
California; or at the Office of the Federal Register, 800 North
Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment becomes effective on November 11, 1996.
Issued in Renton, Washington, on September 30, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-25576 Filed 10-9-96; 8:45 am]
BILLING CODE 4910-13-U
