AD 93-08-12

93-08-12 BOEING: Amendment 39-8559. Docket 92-NM-36-AD.

Applicability: Model 747 series airplanes; as listed in Boeing Service Bulletin 747-53-2349, dated June 27, 1991; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent loss of the structural integrity of the fuselage, accomplish the following:

(a) Prior to the accumulation of 22,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later, unless previously accomplished within the last 2,000 flight cycles; and thereafter at intervals not to exceed 3,000 flight cycles: Perform a detailed visual internal inspection to detect cracks in the areas of the fuselage internal structure listed below, in accordance with Boeing Service Bulletin 747-53-2349, dated June 27, 1991; and prior to further flight, repair any cracks detected, in accordance with FAA- approved procedures.

(1) Sections 41 and 42 upper deck floor beams. (2) Section 42 upper lobe frames. (3) Section 46 lower lobe frames. (4) Section 42 lower lobe frames. (5) Main entry door cutouts. (6) Section 41 body station 260, 340, and 400 bulkheads. (7) Main entry doors.

(b) Prior to the accumulation of 25,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later, unless accomplished previously within the last 2,000 flight cycles; and thereafter at intervals not to exceed 3,000 flight cycles: Perform a detailed visual internal inspection to detect cracks in the Section 46 upper lobe frames, in accordance with Boeing Service Bulletin 747-53-2349, dated June 27, 1991; and prior to further flight, repair any cracks detected, in accordance with FAA-approved procedures.

(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: 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 FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) The inspections shall be done in accordance with Boeing Service Bulletin 747-53-2349, dated June 27, 1991. 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 June 11, 1993.