AD 98-26-23 Airworthiness Directives; Boeing Model 747 Series Airplanes

Models named: 747 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747 series airplanes, line positions 1 through 816 inclusive, certificated in any category. Note 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 (b) 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.

Required as indicated, unless accomplished previously. To detect and correct corrosion and consequent cracking of the rear spar web of the wing center section and adjacent bulkhead fittings at body station 1241, which could result in a fuel leak and consequent fire/explosion in the wheel well of the main landing gear, accomplish the following: (a) Within 18 months after the effective date of this AD, perform a detailed visual inspection to detect corrosion of the rear spar web of the wing center section and adjacent bulkhead fittings at body station 1241, in accordance with Boeing Service Bulletin 747-57-2263, Revision 1, dated December 21, 1995, or Revision 2, dated March 26, 1998, including Appendix A. Thereafter, repeat the inspection at intervals not to exceed 2 years. (1) If no corrosion is detected during the inspection: Prior to further flight, apply corrosion inhibitor in accordance with the service bulletin. (2) If any corrosion is detected during the inspection, and the corrosion is within the limits specified by the service bulletin: Prior to further flight, accomplish the actions specified in paragraphs (a)(2)(i), (a)(2)(ii), and (a)(2)(iii). (i) Remove the corrosion in accordance with the service bulletin. And (ii) Perform a high frequency eddy current inspection to detect cracking in the area of removed corrosion in accordance with the service bulletin. If any crack is detected, prior to further flight, repair it in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; or in accordance with data meeting the type certificate basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. And (iii) Apply corrosion inhibitor in accordance with the service bulletin. (3) If any corrosion is detected during the inspection, and the corrosion exceeds the limits specified by the service bulletin: Prior to further flight, repair the corroded area in accordance with a method approved by the Manager, Seattle ACO; or in accordance with data meeting the type certificate basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. (b) An 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 ACO. 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. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (c) Special 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. (d) Except for the repairs required by paragraphs (a)(2)(ii) and (a)(3), the actions shall be done in accordance with Boeing Service Bulletin 747-57-2263, Revision 1, dated December 21, 1995; or Boeing Service Bulletin 747-57-2263, Revision 2, dated March 26, 1998, including Appendix A, which contains the following list of effective pages: ------------------------------------------------------------------------ Revision Page No. level shown Date shown on page on page ------------------------------------------------------------------------ 1-54............................. 2 March 26, 1998. ------------------------------------------------------------------------ Appendix A ------------------------------------------------------------------------ 1, 2............................. 2 March 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 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. (e) This amendment becomes effective on February 2, 1999. Issued in Renton, Washington, on December 17, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-34096 Filed 12-28-98; 8:45 am] BILLING CODE 4910-13-P