AD 94-04-08

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-10 series airplanes and Model KC-10A (military) airplanes, that requires inspections to detect cracking in the No. 2 engine pylon lower spar forward mount and thrust link fitting attach bolts, replacement of cracked bolts, and the eventual replacement of all bolts made of H-11 material with bolts made of Inconel. This amendment is prompted by reports of failures of these attach bolts due to stress corrosion. The actions specified by this AD are intended to prevent failure of the attach bolts, which could reduce the fail-safe capability of the attachment assembly.

Final rule.

94-04-08 MCDONNELL DOUGLAS: Amendment 39-8828. Docket 93-NM-134-AD. \n\n\tApplicability: Model DC-10-10, -10F, -15, -30, -30F, -40, and -40F series airplanes, and KC-10A (military) airplanes; having fuselage numbers 1 though 374 inclusive; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent failure of the No. 2 engine pylon lower spar forward mount and thrust link fitting attach bolts, which could reduce the fail-safe capability of the attachment assembly, accomplish the following: \n\n\t(a)\tWithin 12 months after the effective date of this AD, perform an ultrasonic inspection to detect cracking of the No. 2 engine pylon lower spar forward mount and thrust link fitting attach bolts made of H-11 material, in accordance with McDonnell Douglas DC-10 Service Bulletin 54-100, Revision 1, dated September 17, 1993. \n\n\t\t(1)\tIf no cracking is detected, repeat the ultrasonic inspection thereafter at intervals not to exceed 18months, until the requirements of paragraph (b) of this AD are accomplished. \n\n\t\t(2)\tIf cracking is detected during any inspection required by this paragraph, prior to further flight, accomplish either paragraph (a)(2)(i) or (a)(2)(ii): \n\n\t\t\t(i)\tReplace the cracked bolt with a new bolt made of H-11 material and continue to inspect in accordance with this paragraph at intervals not to exceed 18 months, until the requirements of paragraph (b) of this AD are accomplished. Or \n\n\t\t\t(ii)\tReplace the cracked bolt with a bolt made of Inconel, and replace the associated hardware, in accordance with the service bulletin. Such replacement constitutes terminating action for required ultrasonic inspections for that bolt. \n\n\t(b)\tWithin 5 years after the effective date of this AD, replace all No. 2 engine pylon lower spar forward mount and thrust link fitting attach bolts made of H-11 material, with bolts made of Inconel, and replace the associated hardware, in accordance with McDonnell Douglas DC-10 Service Bulletin 54-100, Revision 1, dated September 17, 1993. Such replacement constitutes terminating action for the inspections required by 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 Aircraft Certification Office (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: 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 Federal Aviation Regulations (FAR) 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 and replacement shall be done in accordance with McDonnell Douglas DC-10 Service Bulletin 54-100, Revision 1, dated September 17, 1993. 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, P.O. Box 1771, Long Beach, California 90801-1771, Attention: Business Unit Manager, Technical Administrative Support, Dept. L51, Mail Code 2-98. 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, 3229 East Spring Street, Long Beach, 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 March 24, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-10 series airplanes and Model KC-10A (military) airplanes was published in the Federal Register on October 26, 1993 (58 FR 57568). That action proposed to require inspections to detect cracking in the No. 2 engine pylon lower spar forward mount and thrust link fitting attach bolts, replacement of cracked bolts, and the eventual replacement of all bolts made of H-11 material with bolts made of Inconel.\n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.\n\n\tOne commenter supports the proposal.\n\n\tTwo commenters request that the proposed compliance time for the inspections be extended to coincide with normally scheduled maintenance intervals. These commenters suggest that if the compliance times were extended to 24 months, the confusion and expense of special scheduling could be avoided. The FAA does not concur. In developing the proposed compliance time, the FAA primarily considered analyses of the mode of failure of the subject bolts due to stress corrosion, as well as the service history of the fleet. Based on this data and the safety implications presented by loss of fail-safe capability of the attachment assembly should the bolts fail, the FAA has determined that the proposed compliance times of 12 months for the initial inspection and 18 months for the repetitive inspection interval are both appropriate and warranted. Further, the FAA took into account the average utilization rate of the affected fleet, the practical aspects of an orderly inspection of the fleet during regular maintenance periods, and the availability of required replacement parts. The compliance times as proposed should allow ample time for the inspections to be conducted concurrently with scheduled maintenance, thereby minimizing the costs associated with special airplane scheduling. In light of all of these factors, the FAA considers that any extension of the compliance intervals to be unacceptable.\n\n\tAfter 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.\n\n\tThere are approximately 354 Model DC-10 series airplanes and Model KC-10A airplanes of the affected design in the worldwide fleet. The FAA estimates that 206 airplanes of U.S. registry will be affected by this AD.\n\n\tThe inspections required by this AD will take approximately 8 work hours per airplane to accomplish, at an average labor rate of $55 per work hour. Based on these figures, the total cost impact of the inspections requirements of this AD on U.S. operators is estimated to be $90,640, or $440 per airplane, per inspection cycle.\n\n\tThe replacement actions requiredby this AD will take approximately 8 work hours per airplane to accomplish, at an average labor rate of $55 per work hour. Required parts will cost approximately $2,700 per airplane. Based on these figures, the total cost impact of the replacement actions of this AD on U.S. operators is estimated to be $646,840, or $3,140 per airplane.\n\n\tThe total cost impact figures discussed above 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.\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 thepreparation 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 14 CFR part 39 of the Federal Aviation Regulations as follows:\n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\n\t1.\tThe authority citation for part 39 continues to read as follows:\n\nAuthority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.\n\n§ 39.13 - (Amended)\n\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: