AD 96-19-03

This amendment adopts a new airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-10 and MD-11 series airplanes and KC-10A (military) airplanes, that requires repetitive inspections to detect corrosion or failure of the steel Hi-Lok fasteners at the inboard flap inboard track, and replacement of corroded/failed steel Hi-Lok fasteners with inconel Hi-Lok fasteners. This amendment also provides for termination of the repetitive inspections by replacing all of the steel Hi-Lok fasteners with inconel Hi-Lok fasteners. This amendment is prompted by reports of failed and/or corroded steel fasteners found in the inboard flap inboard track due to stress corrosion. The actions specified by this AD are intended to prevent such stress corrosion, which could result in binding of the flap and inability of the flap to extend or retract; this situation may lead to asymmetric flap deployment and subsequent reduced controllability of the airplane during flight.

Final rule.

96-19-03 MCDONNELL DOUGLAS: Amendment 39-9751. Docket 95-NM-212-AD. \n\n\tApplicability: All Model DC-10 and MD-11 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 request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplishedpreviously. \n\n\tTo prevent stress corrosion cracking in the fasteners in the inboard flap inboard track, which could result in binding of the flap and inability of the flap to extend or retract, accomplish the following: \n\n\t(a)\tFor Model DC-10 series airplanes and KC-10A (military) airplanes: Within 18 months after the effective date of this AD, perform a visual inspection to detect corrosion or failure of the steel Hi-Lok fasteners at the inboard flap inboard track in accordance with McDonnell Douglas Service Bulletin DC-10-57-134, dated August 15, 1995. \n\n\t\t(1)\tIf no corrosion or failure is detected, accomplish either paragraph (a)(1)(i) or (a)(1)(ii) of this AD. \n\n\t\t\t(i)\tRepeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 18 months until paragraph (a)(1)(ii) of this AD is accomplished. \n\n\t\t\t(ii)\tReplace all steel Hi-Lok fasteners with inconel Hi-Lok fasteners in accordance with McDonnell Douglas Service Bulletin DC-10-57-134, dated August 15, 1995. Accomplishment of this replacement constitutes terminating action for the repetitive inspection requirements of paragraph (a)(1)(i) of this AD. \n\n\t\t(2)\tIf any corrosion or failure is detected, prior to further flight, accomplish either paragraph (a)(2)(i) or (a)(2)(ii) of this AD, in accordance with McDonnell Douglas Service Bulletin DC-10-57-134, dated August 15, 1995. \n\n\t\t\t(i)\tReplace all corroded/failed steel Hi-Lok fasteners with either like steel Hi-Lok fasteners or inconel Hi-Lok fasteners, in accordance with the service bulletin. Thereafter, repeat the visual inspection required by paragraph (a) of this AD at intervals not to exceed 18 months until paragraph (a)(2)(ii) of this AD is accomplished. \n\n\t\t\t(ii)\tReplace all steel Hi-Lok fasteners with inconel Hi-Lok fasteners, in accordance with McDonnell Douglas Service Bulletin DC-10-57-134, dated August 15, 1995. Accomplishment of this replacement constitutes terminating action for the repetitive inspection requirements of paragraph (a)(2)(i) of this AD. \n\n\t(b)\tFor Model MD-11 series airplanes: Within 18 months after the effective date of this AD, perform a visual inspection to detect corrosion or failures of the steel Hi-Lok fasteners at the inboard flap inboard track in accordance with McDonnell Douglas Service Bulletin MD11-57-031, dated August 15, 1995. \n\n\t\t(1)\tIf no corrosion or failures are detected, accomplish either paragraph (b)(1)(i) or (b)(2)(ii) of this AD. \n\n\t\t\t(i)\tRepeat the inspection required by paragraph (b) of this AD thereafter at intervals not to exceed 18 months until paragraph (b)(1)(ii) of this AD is accomplished. \n\n\t\t\t(ii)\tReplace all steel Hi-Lok fasteners with inconel Hi-Lok fasteners in accordance with McDonnell Douglas Service Bulletin MD11-57-031, dated August 15, 1995. Accomplishment of this replacement constitutes terminating action for the repetitive inspection requirements of paragraph (b)(1)(i) of this AD. \n\n\t\t(2)\tIf any corrosion or failure is detected during the inspection required by paragraph (b) of this AD, prior to further flight, accomplish either paragraph (b)(2)(i) or (b)(2)(ii) of this AD, in accordance with McDonnell Douglas Service Bulletin MD11-57-031, dated August 15, 1995. \n\n\t\t\t(i)\tReplace all corroded/failed steel Hi-Lok fasteners with either like steel Hi-Lok fasteners or inconel Hi-Lok fasteners, in accordance with the service bulletin. Thereafter, repeat the visual inspection required by paragraph (b) of this AD at intervals not to exceed 18 months until paragraph (b)(2)(ii) of this AD is accomplished. \n\n\t\t\t(ii)\tReplace all steel Hi-Lok fasteners with inconel Hi-Lok fasteners in accordance with McDonnell Douglas Service Bulletin MD11-57-031, dated August 15, 1995. Accomplishment of this replacement constitutes terminating action for the repetitive inspection requirements of paragraph (b)(2)(i) 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 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(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 and replacement shall be done in accordance with McDonnell Douglas Service Bulletin DC-10-57-134, dated August 15, 1995 (for Model DC-10 series airplanes); and McDonnell Douglas Service Bulletin MD11-57-031, dated August 15, 1995 (for Model MD-11 series airplanes). 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 October 16, 1996.

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 and MD-11 series airplanes and KC-10A (military) airplanes was published in the Federal Register on April 19, 1996 (61 FR 17261). That action proposed to require repetitive visual inspections to detect corrosion or failure of the steel Hi-Lok fasteners at the inboard flap inboard track. That action also proposed to require replacement of corroded/failed steel Hi-Lok fasteners with inconel Hi-Lok fasteners. In addition, that action proposed to provide for an optional terminating action for the repetitive inspection requirements by replacing all the steel Hi-Lok fasteners with Hi-Lok fasteners 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\nSupport for the Proposal \n\n\tOne commenter supports the proposed rule. \n\nRequest to Allow Installation of Steel Hi-Lok Fasteners \n\n\tOne commenter requests that the proposal be revised to allow the replacement of corroded or damaged steel fasteners with the same part-numbered steel Hi-Lok fasteners, instead of inconel Hi-Lok fasteners. This commenter raises concerns about the timely availability of replacement fasteners. The commenter points out that procuring inconel Hi-Lok fasteners may entail a lead time of several months, but steel Hi-Lok fasteners are readily available. Mandating the use of only inconel fasteners as replacement parts could result in many aircraft being grounded unnecessarily due to the unavailability of parts. \n\n\tThe FAA concurs with this commenter's request. The FAA finds that an acceptable level of safety will be maintained if failed or corroded steel Hi-Lok fasteners are replaced with like steel fasteners and repetitively inspected. (Additionally, the McDonnell Douglas service bulletins referenced in the AD contain a statement indicating: "If inconel Hi-Loks are unavailable, operators may use same material steel Hi-Loks as removed.") This finding, however, does not affect the terminating action provided in this AD, which, if accomplished, requires the replacement of all fasteners with ones made of inconel. \n\n\tParagraphs (a)(2)(i) and (b)(2)(i) of the final rule have been revised to allow fasteners to be replaced with either steel or inconel Hi-Lok fasteners (and repetitively inspected until terminating action is accomplished). \n\nRequest to Extend Initial Compliance Time for Model MD-11's \n\n\tOne commenter requests that paragraph (b) of the proposal be revised to extend the compliance time for the initial inspection of Model MD-11 series airplanes from the proposed 18 months to 72 months. As justification for this request, the commenter points out that there have been no reports of failed fasteners on any Model MD-11 airplane;the only reports of failures have occurred on Model DC-10 series airplanes that had accumulated more than 18,000 total flight cycles. In light of this record, the commenter considers an 18-month compliance time unwarranted for the Model MD-11. \n\n\tThe FAA does not concur with the commenter's request. The flap inboard tracks of both the Model MD-11 and Model DC-10 series airplanes are similar in design; they also operate at similar stresses and in similar environments. In light of this, the flaps of the Model MD-11 may experience the same corrosion problems as the Model DC-10 airplanes have experienced. Additionally, stress corrosion is unpredictable; neither the FAA nor McDonnell Douglas can predict the onset of this phenomenon. Therefore, the FAA has determined that it is necessary to begin inspections as early as is reasonably possible. \n\n\tIn developing an appropriate compliance time for the inspections, the FAA considered not only the degree of urgency associated with addressing the subject unsafe condition, but the availability of required parts and the practical aspect of inspecting the fleet at intervals of time that closely parallel normally scheduled maintenance for the majority of affected operators. In consideration of all of these factors, the FAA has determined that the compliance time, as proposed, is not only appropriate, but warranted. \n\nConclusion \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\nCost Impact \n\n\tThe FAA estimates that 276 airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $33,120, or $120 per airplane, per inspection cycle. \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\nRegulatory Impact \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. The authority citation for part 39 continues to read as follows: \n\nAuthority: 49 U.S.C. 106(g), 40113, 44701.§ 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: