AD 98-09-17 Airworthiness Directives; Boeing Model 747-200F and -200C Series Airplanes

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

All Model 747-200F and -200C series airplanes, 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 (d) 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 prevent reduced controllability of the airplane and/or rapid decompression of the airplane due to fatigue cracking in the upper deck floor beams, accomplish the following: Note 2: For this AD, ``flight cycles'' are considered to be flight cycles with a cabin pressure differential greater than 2.0 pounds per square inch. (a) For airplanes that have accumulated less than 18,000 total flight cycles as of the effective date of this AD: Prior to the accumulation of 15,000 total flight cycles, or within 250 flight cycles after the effective date of this AD, whichever occurs later, inspect the upper chord, web, and strap of the upper deck floor beams at body station (BS) 340 through BS 440 inclusive, and the upper deck floor beams at BS 500 and BS 520, on the right and left sides of the airplane, in accordance with paragraph (a)(1) or (a)(2) of this AD. The inspections shall be [[Page 20313]] accomplished in accordance with Boeing Alert Service Bulletin 747- 53A2420, dated March 26, 1998. (1) Perform a detailed visual inspection to detect cracks in accordance with Figure 2 of the alert service bulletin. (i) Repeat the detailed visual inspection thereafter at intervals not to exceed 25 flight cycles, until the requirements of paragraph (a)(1)(ii) are accomplished. (ii) Within 500 flight cycles after accomplishment of the initial detailed visual inspection, accomplish paragraph (a)(2) of this AD. (2) Perform a one-time open hole high frequency eddy current (HFEC) inspection to detect cracks in accordance with Figure 3 of the alert service bulletin. Accomplishment of this action constitutes terminating action for the repetitive inspection requirements of this AD. (b) For airplanes that have accumulated 18,000 or more total flight cycles as of the effective date of this AD: Within 25 flight cycles after the effective date of this AD, inspect the upper chord, web, and strap of the upper deck floor beams at BS 340 through BS 440 inclusive, and the upper deck floor beams at BS 500 and BS 520, on the right and left sides of the airplane, in accordance with paragraph (b)(1) or (b)(2) of this AD. The inspections shall be accomplished in accordance with Boeing Alert Service Bulletin 747- 53A2420, dated March 26, 1998. (1) Perform a detailed visual inspection to detect cracks in accordance with Figure 2 of the alert service bulletin. (i) Repeat the detailed visual inspection thereafter at intervals not to exceed 25 flight cycles, until the requirements of paragraph (b)(1)(ii) are accomplished. (ii) Within 250 flight cycles after accomplishment of the initial detailed visual inspection, accomplish paragraph (b)(2) of this AD. (2) Perform a one-time open hole HFEC inspection to detect cracks in accordance with Figure 3 of the alert service bulletin. Accomplishment of this action constitutes terminating action for the repetitive inspection requirements of this AD. (c) If any cracking is found during any inspection required by this AD, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, FAA, Transport Airplane Directorate. (d) 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. (e) 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. (f) The inspections shall be done in accordance with Boeing Alert Service Bulletin 747-53A2420, dated 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. (g) This amendment becomes effective on May 11, 1998. Issued in Renton, Washington, on April 20, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-10919 Filed 4-23-98; 8:45 am] BILLING CODE 4910-13-P