[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]



-----------------------------------------------------------------------


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).

-----------------------------------------------------------------------

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