[Federal Register Volume 60, Number 116 (Friday, June 16, 1995)]
[Proposed Rules]
[Pages 31649-31651]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-14768]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-50-AD]
Airworthiness Directives; McDonnell Douglas Model DC-10-10 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 DC-10-10
series airplanes. This proposal would require inspections of the wings
to detect cracks in the aft spar lower cap, in certain stringer
butterfly clips on the bulkheads, and in certain fastener holes; and
repair, if necessary. This proposal would also require modification of
those areas of the wings, which would terminate the repetitive
inspection requirements. This proposal is prompted by reports
indicating that, during fatigue testing of the wing structure, cracks
developed in the aft spar lower cap, in certain stringer
[[Page 31650]]
butterfly clips, and in certain fastener holes due to fatigue-related
stress. The actions specified by the proposed AD are intended to
prevent such fatigue-related cracking, which could lead to the failure
of the aft spar cap and consequently could reduce structural integrity
of the wing.
DATES: Comments must be received by August 14, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-50-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, 2855 Lakewood Boulevard,
Long Beach, California 90846, Attention: Technical Publications
Business Administration, Dept. C1-L51, M.C. 2-60. This information may
be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: John Cecil, Aerospace Engineer,
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los
Angeles Aircraft Certification Office, 3960 Paramount Boulevard,
Lakewood, California 90712-4137; telephone (310) 627-5322; 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 95-NM-50-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. 95-NM-50-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports indicating that, during fatigue
testing of the wing structure of a McDonnell Douglas Model DC-10-10
series airplane, cracks developed in the aft spar lower cap, in the
stringer butterfly clips on the bulkheads at stations Xors=372.000
and Xors=402.000, and in the fastener holes of the access doors of
the inboard upper surface. The cause of this cracking has been
attributed to fatigue-related stress. The effects of such fatigue-
related cracking could lead to the failure of the aft spar cap. This
condition, if not detected and corrected in a timely manner, could
result in reduced structural integrity of the wing.
The FAA has reviewed and approved McDonnell Douglas DC-10 Service
Bulletin 57-36, Revision 7, dated December 11, 1992, which describes
procedures for performing repetitive eddy current inspections of the
wings to detect cracks in the aft spar lower cap, in the stringer
butterfly clips on the bulkheads at stations Xors=372.000 and
Xors=402.000, and in the fastener holes of the access doors of the
inboard upper surface. This service bulletin also describes procedures
for modification of those areas of the wings. For certain airplanes,
the modification involves stress coining the fastener holes and
replacing existing fasteners with interference-fit fasteners, which
will minimize the possibility of crack development. For certain other
airplanes, the modification involves adding shear angles to the panel
supports of the wing and ring pad stress coining the fastener holes of
the access doors of the wing, which will minimize the possibility of
cracks developing in the stringer clips and fastener holes of the
access doors. Accomplishment of these modifications would eliminate the
need for the repetitive inspections.
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 repetitive eddy current inspections of the
wings to detect cracks in the aft spar lower cap, in the stringer
butterfly clips on the bulkheads at stations Xors=372.000 and
Xors=402.000, and in the fastener holes of the access doors of the
inboard upper surface. The proposed AD would also require modification
of those areas of the wings, which would terminate the required
repetitive inspections. These inspection and modification actions would
be required to be accomplished in accordance with the service bulletin
described previously. If any cracks are detected, the repair would be
required to be accomplished in accordance with a method approved by the
FAA.
The FAA points out that AD 94-23-01, amendment 39-9063 (59 FR
58766, November 15, 1994), currently requires repetitive inspections of
the wing rear spar lower cap [reference paragraph (g) of that AD] and
installation of crack preventative modifications [reference paragraph
(h) of that AD] between Xors 410 and Xors 430. Revision 7 of McDonnell
Douglas DC-10 Service Bulletin 57-36, as described above, specifies
procedures for accomplishing the identical inspections and
modifications referenced in AD 94-23-01, but expands the area to
between Xors 409 to Xors 455. In light of this, the FAA has determined
that accomplishment of paragraphs (g) and (h) of AD 94-23-02 are
considered acceptable for compliance with the applicable inspections
and modifications of that area that would be required by this proposed
AD. A note to this effect has been included in the text of the proposed
AD.
As a result of recent communications with the Air Transport
Association (ATA) of America, the FAA has learned that, in general,
some operators may misunderstand the legal effect of AD's on airplanes
that are identified in the applicability provision of the AD, but that
have been altered or repaired in the area addressed by the AD. The FAA
points out that all airplanes identified in the applicability provision
of an AD are legally subject to the AD. If an airplane has been altered
or repaired in the affected area in such a way as to affect compliance
with the AD, the owner or operator is required to obtain FAA approval
for an alternative method of compliance with the AD, in accordance with
the paragraph of each AD that provides for such approvals. A note has
been included in this notice to clarify this long-standing requirement.
[[Page 31651]]
There are approximately 53 Model DC-10-10 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 53
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 262 work hours per airplane to accomplish
the proposed actions, and that the average labor rate is $60 per work
hour. Required parts would cost approximately $125,609 per airplane.
Based on these figures, the total cost impact of the proposed AD on
U.S. operators is estimated to be $7,490,437, or $141,329 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 95-NM-50-AD.
Applicability: Model DC-10-10 series airplanes, as listed in
McDonnell Douglas DC-10 Service Bulletin 57-36, Revision 7, dated
December 11, 1992, 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 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.
Note 2: Inspections and modifications required by paragraphs (g)
and (h) of AD 94-23-01, amendment 39-9063, accomplished prior to the
effective date of this amendment in accordance with McDonnell
Douglas DC-10 Service Bulletin 57-123, dated June 8, 1993, or
McDonnell Douglas DC-10 Service Bulletin 57-36, Revision 6, dated
February 25, 1991, are considered acceptable for compliance with the
applicable inspections and modifications required by this amendment
for the affected structure.
To prevent fatigue-related cracking, which could lead to the
failure of the aft spar cap and subsequent reduced structural
integrity of the wing, accomplish the following:
(a) Prior to the accumulation of 15,000 total landings or within
2,000 landings after the effective date of this AD, whichever occurs
later, perform an eddy current inspection of the wings to detect
cracks in the aft spar lower cap, in the stringer butterfly clips on
the bulkheads at stations Xors=372.000 and Xors=402.000,
and in the fastener holes of the access doors of the inboard upper
surface, in accordance with McDonnell Douglas DC-10 Service Bulletin
57-36, Revision 7, dated December 11, 1992.
(1) If no cracks are detected, repeat the inspection thereafter
at intervals not to exceed 2,000 landings until the modification
required by paragraph (b) of this AD is accomplished.
(2) If any crack is detected, prior to further flight, repair in
accordance with a method approved by the Manager, Los Angeles
Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate.
(b) Prior to the accumulation of 42,000 total landings or within
5 years after the effective date of this AD, whichever occurs later,
modify the aft spar lower cap, the stringer butterfly clips on the
bulkheads at stations Xors=372.000 and Xors=402.000, and
the fastener holes of the access doors of the inboard upper surface
of the wings, in accordance with McDonnell Douglas DC-10 Service
Bulletin 57-36, Revision 7, dated December 11, 1992. Accomplishment
of this modification constitutes terminating action for the
repetitive inspection requirement 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 ACO. 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.
Issued in Renton, Washington, on June 12, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-14768 Filed 6-15-95; 8:45 am]
BILLING CODE 4910-13-U
