AD 98-26-22

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-10 series airplanes and KC-10A (military) airplanes, that requires repetitive inspections to detect cracking of the lower cap of the wing rear spar, and repair, if necessary. For certain airplanes, this AD also provides for an optional terminating modification for the repetitive inspections. This amendment is prompted by reports of fatigue cracks found in the lower cap of the wing rear spar. The actions specified by this AD are intended to detect and correct fatigue cracking of the lower cap of the wing rear spar, which could result in reduced structural integrity of the airplane.

Final rule.

98-26-22 MCDONNELL DOUGLAS: Amendment 39-10965. Docket 97-NM-288-AD. \n\n\tApplicability: Model DC-10 series airplanes and KC-10A (military) airplanes, as listed in McDonnell Douglas Alert Service Bulletin DC10-57A137, dated July 31, 1997; 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 (d) 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 accomplished previously. \n\n\tTo detect and correct fatigue cracking of the lower cap of the wing rear spar, which could result in reduced structural integrity of the airplane, accomplish the following: \n\n\t(a)\tConduct an eddy current surface inspection to detect cracking of the lower cap of the wing rear spar, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin DC10-57A137, dated July 31, 1997, or Revision 01, dated May 26, 1998; at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD. Thereafter, repeat this inspection at intervals not to exceed 1,500 landings, except as provided by paragraph (c) of this AD. \n\n\t\t(1)\tPrior to the accumulation of 7,000 total landings, or within 18 months after the effective date of this AD, whichever occurs later. Or \n\n\t\t(2)\tWithin 1,500 landings after the accomplishment of the inspection of Principal Structural Elements 57.10.007 and 57.10.008, in accordance with AD 95-23-09, amendment 39-9429. \n\n\t(b)\tIf any crack is found during any inspection required by paragraph (a) of this AD, accomplish paragraph (b)(1) or (b)(2) of this AD, as applicable. \n\n\t\t(1)\tExcept as provided by paragraph (c) of this AD, for any crack identified in Condition 2 or Condition 3 of McDonnell Douglas Alert Service Bulletin DC10-57A137, Revision 01, dated May 26, 1998: Prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; or accomplish the permanent repair of the spar cap in accordance with Revision 01 of the alert service bulletin, and repeat the eddy current surface inspection required by paragraph (a) of this AD thereafter at the times specified in Revision 01 of the alert service bulletin for that repaired spar cap. \n\n\t\t(2)\tFor any crack identified in Condition 4 of McDonnell Douglas Alert Service Bulletin DC10-57A137, Revision 01, dated May 26, 1998: Accomplish either paragraph (b)(2)(i), or paragraphs (b)(2)(ii) and (b)(2)(iii) of this AD. \n\n\t\t\t(i)\tPrior 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\t\t(ii)\tPrior to further flight, temporarily repair the spar cap in accordance with Revision 01 of the alert service bulletin. Repeat the eddy current surface inspection required by paragraph (a) of this AD thereafter at the applicable times specified in the alert service bulletin for that repaired spar cap, until accomplishment of paragraph (b)(3)(iii) of this AD. \n\n\t\t\t(iii)\tAt the applicable time specified in the alert service bulletin, permanently repair the crack in accordance with Revision 01 of the alert service bulletin. Accomplishment of the permanent repair constitutes terminating action for the repetitive eddy current surface inspection requirements of paragraph (b)(2)(ii) of this AD. Within 10,000 landings following accomplishment of the permanent repair, repeat the eddy current surface inspection required by paragraph (a) of this AD thereafter at the applicable times specified in Revision 01 of the alert service bulletin for that permanently repaired spar cap. \n\n\t(c)\tFor airplanes on which no crack (Condition 1) or any crack that is specified in Condition 2 of McDonnell Douglas Alert Service Bulletin DC10-57A137, Revision 01, dated May 26, 1998, is detected: Accomplishment of the preventative modification specified in paragraphs (c)(1), (c)(2), (c)(3), (c)(4), (c)(5), and (c)(6) of this AD, in accordance with Revision 01 of the alert service bulletin, constitutes terminating action for the repetitive inspection requirements of paragraph (a) of this AD. \n\n\t\t(1)\tRemove existing sealant as required. \n\t\t(2)\tRemove affected taper-lok fasteners. \n\t\t(3)\tReam holes to remove taper. \n\t\t(4)\tCold work affected holes. \n\t\t(5)\tPerform an eddy current inspection using the open hole technique to detect cracks inside the holes. If any crack is detected, prior to further flight, repair in accordance with a method approved by Manager, Los Angeles ACO. \n\t\t(6)\tInstall new fasteners. \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 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 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 the airplane to a location where the requirements of this AD can be accomplished. \n\n\t(f)\tCertain actions shall be done in accordance with McDonnell Douglas Alert Service Bulletin DC10-57A137, dated July 31, 1997, or McDonnell Douglas Alert Service Bulletin DC10-57A137, Revision 01, dated May 26, 1998. 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 Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. 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 February2, 1999.

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 Model DC-10 Series Airplanes and KC-10A (military) airplanes was published in the Federal Register on March 26, 1998 (63 FR 14654). That action proposed to require repetitive inspections to detect cracking of the lower cap of the wing rear spar, and repair, if necessary. \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\tSeveral commenters support the proposed rule. \n\nRequests to Reference Latest Service Bulletins \n\n\tSeveral commenters request that the proposed AD be revised to reference Revision 01 of McDonnell Douglas Alert Service Bulletin DC10-57A137, dated May 26, 1998, and McDonnell Douglas Service Bulletin DC10-57-138, dated May 28, 1998. These commenters state that Revision 01 of McDonnell Douglas Alert Service Bulletin DC10-57A137 contains new repair procedures and that McDonnell Douglas Service Bulletin DC10-57-138 contains an optional preventative modification. Without incorporation of this information, the commenters state that operators would have to seek approval from the FAA for alternative methods of compliance, which would create additional work for operators and the FAA. \n\n\tThe FAA concurs with the commenters' requests to reference the latest service bulletins. Since issuance of the notice of proposed rulemaking (NPRM), the FAA has reviewed and approved the service bulletins mentioned by the commenters. \n\n\tThe inspection procedures described in Revision 01 of McDonnell Douglas Alert Service Bulletin DC10-57A137 are identical to those described in the original version of that alert service bulletin (which was referenced in the proposed AD as the appropriate source of service information for accomplishment of the eddy currentsurface inspection). However, Revision 01 revises the original cracking conditions and adds new procedures for specific repairs. The FAA finds that accomplishment of these new repair procedures will maintain an adequate level of safety. Therefore, in lieu of accomplishing the required repair in accordance with a method approved by the FAA, operators can elect to accomplish the new subject repair. The FAA has revised paragraph (b) of the final rule accordingly. \n\n\tMcDonnell Douglas Service Bulletin DC10-57-138 describes procedures for a preventative modification that would eliminate the need for certain repetitive inspections described in McDonnell Douglas Alert Service Bulletin DC10-57A137. The preventative modification involves the following: \n\n\t1. Removing affected taper-lok fasteners; \n\t2. Reaming holes to remove taper; \n\t3. Cold working affected holes; \n\t4. Performing an eddy current inspection using the open hole technique to detect cracks inside the holes, and repair, if necessary; and \n\t5. Installing new fasteners. \n\n\tThe FAA finds that the preventative modification specified in that service bulletin may be provided as an optional terminating action for certain repetitive inspection requirements of the final rule. The FAA is not mandating the preventative modification of the rear spar lower cap for several reasons: \n\n\t1. Accessing the taper-lok fasteners of the lower cap of the wing rear spar for inspection is easily accomplished. \n\t2. The cracking of the spar emanating from the fastener holes is easily detectable by means of an eddy current surface inspection. \n\t3. The failure of a fastener may adversely affect the structural integrity of the airplane; however, the eddy current surface inspections will preclude the occurrence of multiple failed fasteners, which could result in a catastrophic failure. \n\n\tTherefore, for certain airplanes, the FAA has added a new paragraph (c) to the final rule to provide for this option, and hasrevised the cost impact information accordingly. \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\tThere are approximately 283 Model DC-10 Series Airplanes and KC-10A (military) airplanes of the affected design in the worldwide fleet. The FAA estimates that 201 airplanes of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per airplane to accomplish the required inspection, 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 $96,480, or $480 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\n\tShould an operator elect to accomplish the optional terminating action rather than continue the repetitive inspections, it would take approximately 15 (for Group 1 airplanes) or 6 (for Group 2 airplanes) work hours per airplane to accomplish the modification, at an average labor rate of $60 per work hour. Required parts will cost approximately $3,546 per airplane (for Group 1 airplanes) and $2,145 per airplane (for Group 2 airplanes). Based on these figures, the cost impact of this optional terminating action is estimated to be $4,446 per airplane (for Group 1 airplanes) and $2,505 per airplane (for Group 2 airplanes). \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 andthe 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. \n\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: