AD 98-20-25 Airworthiness Directives; Boeing Model 747-100 Series Airplanes

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

Model 747-100 series airplanes, line positions 1 through 87 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 (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.

Required as indicated, unless accomplished previously. To detect and correct fatigue cracking of the Body Station (BS) 1480 bulkhead outer chord and longeron splice fitting, which could result in reduced structural integrity of the fuselage and the inability to carry limit load, accomplish the following: (a) Prior to the accumulation of 10,000 total flight cycles, or within 45 days after the effective date of this AD, whichever occurs later, accomplish either paragraph (a)(1) or (a)(2) of this AD. (1) Perform a detailed visual inspection to detect cracking of the longeron splice fitting at BS 1480, the forward side of the outer chord of the BS 1480 bulkhead at the longeron splice fitting attachment bolts, and the aft side of the outer chord of the BS 1480 bulkhead within two inches above the outer chord splice fitting, on both the left and right sides of the airplane. Note 2: Figure 5 of Boeing Alert Service Bulletin 747-53A2390, dated July 31, 1997, provides an exploded view of the structural components of the splice area for the purpose of parts identification. [However, paragraph (a)(1) of this AD does not require the inspection described in Figure 5.] (i) If any cracking is detected, 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 who has been authorized by the Manager, Seattle ACO, to make such findings. (ii) Repeat the detailed visual inspection thereafter at intervals not to exceed 250 flight cycles, until the initial inspection required by paragraph (a)(2) of this AD is accomplished. (2) Perform detailed visual and eddy current inspections to detect cracking of the upper and lower bulkhead, bulkhead outer chord, web, skin, splice components, and lower bulkhead/stringer interface, in accordance with Figures 5 and 8 of Boeing Alert Service Bulletin 747-53A2390, dated July 31, 1997. Additionally, for airplanes on which the inspection in ``Plan B'' of the service bulletin is accomplished, modify the skin splice plate, the outer chord splice fitting, and the stringer interface of the lower bulkhead, in accordance with the Accomplishment Instructions of the alert service bulletin. Accomplishment of these actions constitutes terminating action for the repetitive inspection requirements of paragraph (a)(1) of this AD. (i) If any cracking is detected, prior to further flight, repair in accordance with the alert service bulletin, except as provided by paragraph (b) of this AD. (ii) Repeat the inspections thereafter in accordance with the flight safety inspection program specified in Figures 1 and 3 of the alert service bulletin. (b) Where the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, 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 Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. (c) 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (d) 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. (e) Except as provided by paragraphs (a)(1)(i) and (b) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2390, dated July 31, 1997. 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. (f) This amendment becomes effective on October 7, 1998. [[Page 50511]] Issued in Renton, Washington, on September 15, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-25148 Filed 9-21-98; 8:45 am] BILLING CODE 4910-13-P