AD 96-26-04 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 having line numbers 1 through 678 inclusive; on which the Section 41 frame replacement in zone 1 specified in Boeing Service Bulletin 747-53-2272 has not been accomplished; certificated in any category. Note 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.

Required as indicated, unless accomplished previously. To detect and correct fatigue cracking of body station (BS) 300 and BS 320 fuselage frames adjacent to the nose wheel well (NWW), which could result in collapse of the NWW pressure bulkhead, and subsequent rapid decompression of the airplane, accomplish the following: (a) Prior to the accumulation of 10,000 total flight cycles, or within 50 flight cycles after the effective date of this AD, whichever occurs later, perform a detailed visual inspection to detect fatigue cracking of the inner chord and web of the left side and right side of BS 300 and BS 320 fuselage frames from the nose wheel well (NWW) side panel outboard to stringer 39, in accordance with normal maintenance practices. Pay particular attention to the area where the NWW vertical beam inner chord interfaces with the fuselage frame. (1) If no cracking is detected, repeat the detailed visual inspection thereafter at intervals not to exceed 100 flight cycles. (2) 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. (b) Prior to the accumulation of 10,000 total flight cycles, or within 50 flight cycles after the effective date of this AD, whichever occurs later, perform a detailed one-time visual inspection to detect fatigue cracking of the left and right side vertical beam webs and chords of the NWW at BS 300 and BS 320, in accordance with normal maintenance procedures. (1) If no cracking is detected, no further action is required by this paragraph. (2) If any cracking is detected, prior to further flight, repair in accordance with a method approved by the Manager, Seattle ACO. (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 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. Note 2: 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) This amendment becomes effective on January 6, 1997. Issued in Renton, Washington, on December 20, 1996. S. R. Miller, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 96-33041 Filed 12-30-96; 8:45 am] BILLING CODE 4910-13-U