AD 99-10-10

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-200, -300, and -400 series airplanes, that requires replacement of fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut with new corrosion-resistant pins. This amendment is prompted by reports of cracked fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut due to fatigue and corrosion. The actions specified by this AD are intended to prevent cracking or corrosion of the fuse pins of the nacelle strut, which could result in failure of the fuse pin and strut-to-wing attachment, and consequent loss of the strut and separation of the engine from the airplane.

Final rule

99-10-10 BOEING: Amendment 39-11163. Docket 98-NM-286-AD. \n\n\tApplicability: Model 747-200 and -300 series airplanes equipped with General Electric Model CF6-80C2 series engines, and Model 747-400 series airplanes; as listed in Boeing Service Bulletin 747-54-2155, Revision 2, dated June 6, 1996, certificated in any category; except those airplanes on which modifications of the strut/wing structure have been accomplished in accordance either of the following AD's: \n\n\t AD 95-13-05, amendment 39-9285 (60 FR 33333, June 28, 1995), or \n\n\t AD 95-13-06, amendment 39-9286 (60 FR 33338, June 28, 1995). \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 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 accomplished previously. \n\n\tTo prevent cracking or corrosion of the fuse pins of the nacelle strut, which could result in failure of the fuse pin and strut-to-wing attachment, and consequent loss of the strut and separation of the engine from the airplane, accomplish the following: \n\n\t(a)\tWithin 10 months after the effective date of this AD, replace the fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut with new corrosion-resistant pins, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-54-2155, Revision 2, dated June 6, 1996. \n\n\tNOTE 2: Replacement of the fuse pins accomplished prior to the effective date of this AD in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-54-2155, dated September 23, 1993, or Revision 1, dated December 8, 1994, is considered acceptable for compliance with the applicable action specified in this amendment. \n\n\tNOTE 3: All fuse pins in the strut do not have to be replaced at the same time; however, the fuse pins do have to be replaced in sets, as specified in Boeing Service Bulletin 747-54-2155, Revision 2, dated June 6, 1996. \n\n\t(b)\tAccomplishment of the replacement of the fuse pins specified in paragraph (a) of this AD constitutes terminating action for the repetitive inspections of the fuse pins of the upper link, required by AD 97-14-06, amendment 39-10064; of the fuse pins of the midspar fitting, required by AD 92-24-51, amendment 39-8439; and of the fuse pins of the diagonal brace, required by AD 93-03-14, amendment 39-8518. \n\nAlternative Methods of Compliance \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, Seattle 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, Seattle ACO. \n\n\tNOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \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\nIncorporation by Reference \n\n\t(e)\tThe replacement shall be done in accordance with Boeing Service Bulletin747-54-2155, Revision 2, dated June 6, 1996. 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 Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; 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 June 15, 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 Boeing Model 747-200, -300, and -400 series airplanes was published in the Federal Register on February 18, 1999 (64 FR 8024). That action proposed to require replacement of fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut with new corrosion-resistant pins. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the two comments received. \n\n\tOne commenter supports the proposed rule. The second commenter states that the proposed rule will have no impact on it; therefore, the commenter supports the proposed rule.\n\n Conclusion \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\nCost Impact \n\n\tThere are approximately 282 airplanes of the affected design in the worldwide fleet. The FAA estimates that 43 airplanes of U.S. registry will be affected by this AD, that it will take approximately 105 work hours per airplane to accomplish the required replacement, and that the average labor rate is $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $270,900, or $6,300 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\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: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: