AD 95-24-01

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas DC-10-10 series airplanes, that requires 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 amendment also requires modification of those areas of the wings, which terminates the repetitive inspection requirements. This amendment is prompted by reports indicating that, during fatigue testing of the wing structure, cracks developed in the aft spar lower cap, in certain stringer butterfly clips, and in certain fastener holes due to fatigue-related stress. The actions specified by this AD are intended to prevent such fatigue- related cracking, which could lead to the failure of the aft spar cap and consequently could reduce the structural integrity of the wing.

Final rule.

95-24-01 MCDONNELL DOUGLAS: Amendment 39-9433. Docket 95-NM-50-AD. \n\n\tApplicability: 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. \n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 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. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tNOTE 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. \n\n\tTo 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: \n\n\t(a)\tPrior 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. \n\n\t\t(1)\tIf 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. \n\n\t\t(2)\tIf 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. \n\n\t(b)\tPrior 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. \n\n\t(c)\tAn 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. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. \n\n\t(d)\tSpecial 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. \n\n\t(e)\tThe inspections, repair, and modification shall be done in accordance with McDonnell Douglas DC-10 Service Bulletin 57-36, Revision 7, dated December 11, 1992. 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. \n\n\t(f)\tThis amendment becomes effective on December 27, 1995.

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 DC-10-10 series airplanes was published in the Federal Register on June 16, 1995 (60 FR 31649). That action proposed to 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. That action also proposed to require modification of those areas of the wings, which would constitute terminating action for the required repetitive inspections. \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received. \n\n\tThe commenter supports the proposed rule. \n\n\tAfter careful review ofthe available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed. \n\n\tThere 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 will be affected by this AD, that it will take approximately 262 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $125,609 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $7,490,437, or $141,329 per airplane. \n\n\tThe cost impact figure discussed above 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. \n\n\tThe 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. \n\n\tFor 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." \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment \n\n\tAccordingly, 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:\n\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: \n\nAuthority: 49 USC 106(g), 40101, 40113, 44701. \n\n§ 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: