AD 2000-04-17 Airworthiness Directives; Boeing Model 747-100, -200, and -300 Series Airplanes

Models named: 747-100, -200, -300 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747-100, -200, and -300 series airplanes as listed in Boeing Alert Service Bulletin 747-53A2431; 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. Note 2: The actions specified by Boeing Alert Service Bulletin 747-53A2431, dated February 10, 2000, for the upper deck floor beams located at body stations (BS) 340 and 360, also are applicable to both the left and right sides of the floor beam at BS 380 between buttock lines (BL) 40 and 76. To prevent failure of the upper deck floor beams due to fatigue cracking at BS 340, 360, and 380; which could result in rapid decompression and consequent reduced controllability of the airplane; accomplish the following: Inspections and Repair (a) Prior to the accumulation of 28,000 total flight cycles, or within 60 days after the effective date of this AD, whichever occurs later, perform the inspections required by either paragraph (a)(1) or (a)(2) of this AD, as applicable. (1) Gain access to the upper deck floor beams from above the upper deck floor, and perform an open-hole high frequency eddy current (HFEC) inspection to detect cracking of the upper deck floor beams at BS 340 and 360, and on both the left and right sides of the floor beam at BS 380 between BL 40 and 76; in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2431, dated February 10, 2000. (i) If no cracking is found, perform the actions required by either paragraph (a)(1)(i)(A) or (a)(1)(i)(B) of this AD, in accordance with the alert service bulletin. (A) Repeat the inspection required by paragraph (a)(1) of this AD thereafter at intervals not to exceed 3,000 flight cycles. (B) Modify (oversize) the floor panel attachment fastener holes as specified in Figure 5 of the alert service bulletin, and repeat the inspection required by paragraph (a)(1) of this AD within 10,000 flight cycles. Thereafter, repeat the inspection at intervals not to exceed 3,000 flight cycles. (ii) If any cracking is found, prior to further flight, repair 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 certification basis of the airplane approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the FAA to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. (2) Gain access to the upper deck floor beams from below the upper deck floor; modify the floor panel attachment clipnuts at BS 340 and 360, and on both the left and right sides of the floor beam at BS 380 between BL 40 and 76; and perform a surface HFEC inspection to detect cracking of the floor beams at those body stations; in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2431, dated February 10, 2000. (i) If no cracking is found, repeat the inspection required by paragraph (a)(2) of this AD thereafter at intervals not to exceed 750 flight cycles. (ii) If any cracking is found, prior to further flight, repair in accordance with a method approved by the Manager, Seattle ACO, or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company DER who has been authorized by the FAA to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. Alternative Methods of Compliance (b)(1) 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. (2) An alternative method of compliance for paragraphs (a)(1)(ii) and (a)(2)(ii) of this AD that provides an acceptable level of safety may be used in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. Special Flight Permits (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. Incorporation by Reference (d) Except as specified in paragraphs (a)(1)(ii) and (a)(2)(ii), the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2431, dated February 10, 2000. 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 March 15, 2000. Issued in Renton, Washington, on February 22, 2000. Donald L. Riggin, Acting Manager Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 00-4568 Filed 2-28-00; 8:45 am] BILLING CODE 4910-13-U