AD 95-11-07

This amendment adopts a new airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-10 series airplanes and KC-10A (military) airplanes, that requires inspections to detect cracking of H-11 attach bolts of the upper vertical stabilizer and replacement of these bolts and associated nuts with Inconel bolts and nuts. This amendment is prompted by failure of the attach bolts of the upper vertical stabilizer due to stress corrosion. The actions specified by this AD are intended to prevent undetected cracked or failed attach bolts that may lead to reduced structural integrity of the vertical stabilizer.

Final rule.

95-11-07 MCDONNELL DOUGLAS: Amendment 39-9242. Docket 94-NM-79-AD. \n\n\tApplicability: Model DC-10-10, -10F, -15, -30, -30F, -40, and -40F series airplanes, and KC-10A (military) airplanes; 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 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 (d) 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\tTo prevent undetected cracked or failed attach bolts that may lead to reduced structural integrity of the vertical stabilizer, accomplish the following: \n\n\t(a)\tWithin 12 months after the effective date of this AD, perform an ultrasonic inspection to detect cracking in the attach bolts of the upper vertical stabilizer, in accordance with McDonnell Douglas DC-10 Service Bulletin 55-20, Revision 2, dated August 4, 1994, unless accomplished within the last 18 months prior to the effective date of this AD in accordance with McDonnell Douglas DC-10 Service Bulletin 55-20, Revision 1, dated March 8, 1991, or Revision 2, dated August 4, 1994. \n\n\t\t(1)\tIf no cracking is detected in any bolt, repeat the inspection of the uncracked bolt thereafter at intervals not to exceed 18 months, untilthe requirements of paragraph (c) of this AD are accomplished. \n\n\t\t(2)\tIf cracking is detected in any bolt, prior to further flight, replace the cracked bolt and associated nut with a new Inconel attach bolt and associated nut, in accordance with the service bulletin. No further action is required by this AD for the new Inconel bolts and associated nuts. \n\n\t(b)\tCompliance with the inspections required by paragraph (a) of this AD constitutes compliance with the inspections and reports required by paragraph (b) of AD 93-17-09, amendment 39-8680, for Principal Structural Element (PSE) 55.10.001/002. However, after installation of new Inconel bolts and associated nuts, in accordance with the requirements of paragraphs (a) and (c) of this AD, PSE 55.10.001/002 must continue to be inspected in accordance with AD 93-17-09. \n\n\t(c)\tWithin 5 years after the effective date of this AD, replace all H-11 attach bolts and associated nuts of the upper vertical stabilizer with new Inconel attach bolts and associated nuts, in accordance with McDonnell Douglas DC-10 Service Bulletin 55-20, Revision 1, dated March 8, 1991; or Revision 2, dated August 4, 1994. Such replacement constitutes terminating action for the requirements of this AD. \n\n\t(d)\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), 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. \n\n\tNOTE 2: 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(e)\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 theairplane to a location where the requirements of this AD can be accomplished. \n\n\t(f)\tThe inspections and replacement shall be done in accordance with McDonnell Douglas DC-10 Service Bulletin 55-20, Revision 1, dated March 8, 1991, or McDonnell Douglas DC-10 Service Bulletin 55-20, Revision 2, dated August 4, 1994. 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. \n\n\t(g)\tThis amendment becomes effective on June 29, 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 all McDonnell Douglas Model DC-10 series airplanes and KC-10A (military) airplanes was published in the Federal Register on September 19, 1994 (59 FR 47825). That action proposed to require inspections to detect cracking of H-11 attach bolts of the upper vertical stabilizer and replacement with Inconel attach bolts and associated nuts. \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 proposed rule. \n\n\tThe Air Transport Association of America, on behalf of one of its member operators, requests that the 18-month compliance time for the repetitive inspections required by proposed paragraph (a)(1) be extended to 24 months. The commenter states that this extension in the compliance time would coincide with regularly scheduled maintenance visits, and would result in savings of over $2,800 per airplane if operators were not required to "special schedule" these airplanes for the inspection. \n\n\tThe FAA does not concur with the commenter's request to extend the compliance time. The FAA has determined that the compliance time, as proposed, represents the maximum interval of time allowable for the affected airplanes to continue to operate prior to accomplishing the required inspections without compromising safety. Further, the FAA's intent is to have the compliance time for the repetitive inspections coincide with the 18-month interval recommended by the manufacturer. Additionally, since the FAA has received an additional report of bolt failure, the FAA finds that the 18-month interval for the repetitive inspections is appropriate to ensure safety of the fleet. \n\n\tAdditionally, the Service Action Requirements Document (SARD) that is referenced in this final rule was developed by McDonnell Douglas only after extensive and detailed consultations with large numbers of operators of Model DC-10 series airplanes. The compliance times were based on these consultations and developed in order to minimize the economic impact on operators without compromising the safety objectives of this AD. Further, the FAA has received no data substantiating that an extension of the compliance time to 24 months would provide an acceptable level of safety. \n\n\tOne commenter requests that the requirement to replace all H-11 attach bolts and associated nuts within 5 years as proposed in paragraph (c) be revised to be an option. The commenter asserts that these bolts need not be replaced within 5 years since the cause of the failed bolts has been attributed to stress corrosion, not fatigue. Further, the commenter contends that the bolts are easily inspected and that damage would be easily detectable. Finally, the commenter believes that service history(three incidents of one failed bolt per airplane in over 20 years) supports its assertion that mandatory replacement of these bolts is unnecessary. \n\n\tThe FAA does not concur. The FAA finds that bolt failure due to stress corrosion is less predictable than failure due to fatigue; therefore, the requirement to replace these bolts is even more crucial. Furthermore, the FAA does not consider that these inspections are easy to perform. Finally, although only one bolt has failed per airplane, thus far, the FAA has no technical data to substantiate preclusion of potential multiple failures of this bolt on any Model DC-10 series airplane. Additionally, the FAA has determined that long term continued operational safety will be better assured by actual modification of the airframe to remove the source of the problem, rather than by repetitive inspections. Long term inspections may not be providing the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous repetitive inspections, has led the FAA to consider placing less emphasis on special procedures and more emphasis on design improvements. The replacement requirement is in consonance with these considerations. \n\n\tTwo commenters request that the cost estimate be revised, since it seems to be unrealistic. One of these commenters requests that the estimated cost of accomplishing the proposed actions include the time necessary to obtain access to the area, remove and re-install access doors, remove sealant from bolts, and remove and re-install bolts. The FAA does not concur. The appropriate number of work hours to accomplish the required actions (specified as 2 for the inspection and 8 for the replacement of the bolts) in the economic impact information, below, was provided to the FAA by the manufacturer based on the best data available to date. This number does not include the time required to gain access, remove parts, remove sealant from parts, and close up. The cost analysis in AD rulemaking actions typically does not include these costs, since there may be great variations in them from operator to operator. \n\n\tThe FAA has recently reviewed the figures it has used over the past several years in calculating the economic impact of AD activity. In order to account for various inflationary costs in the airline industry, the FAA has determined that it is necessary to increase the labor rate used in these calculations from $55 per work hour to $60 per work hour. The economic impact information, below, has been revised to reflect this increase in the specified hourly labor rate. \n\n\tAs 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 added to this final rule to clarify this long-standing requirement. \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 with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\n\tThere are approximately 426 McDonnell Douglas Model DC-10 series airplanes and KC-10A (military) airplanes ofthe affected design in the worldwide fleet. The FAA estimates that 269 airplanes of U.S. registry will be affected by this AD. \n\n\tIt will take approximately 2 work hours per airplane to accomplish the required inspections at an average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $32,280, or $120 per airplane. \n\n\tIt will take approximately 8 work hours per airplane to accomplish the required replacements at an average labor rate of $60 per work hour. Required parts will cost approximately $9,009 per airplane. Based on these figures, the total cost impact of the replacements requirements of this AD on U.S. operators is estimated to be $2,552,541, or $9,489 per airplane. \n\n\tBased on the above figures, the total cost impact of the inspection and replacement requirements of this AD on U.S. operators is estimated to be $2,584,821, or $9,609. \n\n\tThe total cost impact figure discussed above is basedon 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\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: