AD 93-02-16

93-02-16 BOEING: Amendment 39-8500. Docket 93-NM-01-AD.

Applicability: Model 747 airplanes, line numbers 1 through 200, inclusive; having 7079- T6 aluminum latch support fittings; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent the cargo door from opening during flight of the airplane, which could result in rapid decompression of the airplane, accomplish the following:

(a) Within 60 days after the effective date of this AD, perform a high frequency eddy current (HFEC) inspection to detect cracking on all surfaces of the upper recess in each 7079-T6 aluminum latch support fitting of the cargo doorway in accordance with Boeing Service Bulletin 747-53A2377, Revision 1, dated January 28, 1993.

(1) If any fitting is found cracked, prior to further flight, replace the cracked fitting with a 7075-T73 aluminum fitting in accordance with the service bulletin.

(2) Repeat the HFEC inspection on any uncracked fitting, thereafter, at intervals not to exceed 18 months, until all affected fittings are replaced with 7075-T73 aluminum fittings in accordance with the service bulletin.

(b) Replacement of a 7079-T6 aluminum fitting with a 7075-T73 aluminum fitting in accordance with Boeing Service Bulletin 747-53A2377, Revision 1, dated January 28, 1993, constitutes terminating action for the inspection requirements of this AD for that fitting.

(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 obtainedfrom 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 and replacement shall be done in accordance with Boeing Service Bulletin 747-53A2377, Revision 1, dated January 28, 1993. 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 March 11, 1993.