AD 90-11-08

90-11-08 BOEING: Amendment 39-6609. Docket No. 89-NM-189-AD.

Applicability: Model 747-200 and 747-300 series airplanes, listed in Boeing Alert Service Bulletin 747-57A2247, Revision 3, dated June 22, 1989, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent fuel or fuel vapors from entering the forward cargo compartment, accomplish the following:

A. Within the next 50 flight hours after the effective date of this AD, unless previously accomplished within the last 350 flight hours, and thereafter at intervals not to exceed 400 flight hours, conduct a visual inspection for fuel leaks at the forward side of the forward wall of the center wing fuel tank (body station 1000 pressure bulkhead) between fuselage stringers S- 37 and S-39, left and right side of the airplane, with specific attention to the bathtub fittings at fuselage stringer S-38 (Body Buttline 78.5, left and right).

1. If fuel leakage or fuel staining is detected, prior to further flight, accomplish the drag splice fitting modification in accordance with paragraph B., below.

2. If no sign of fuel leakage is found, but the sealant around the nut is cracked or damaged, within the next 400 flight hours, accomplish the drag splice fitting modification in accordance with paragraph B., below.

B. Within the next 36 months after the effective date of this AD, install the bolt head retention caps, replace the H-11 steel drag splice fitting bolts with Inconel 718 bolts, and reseal the drag splice fitting, in accordance with Boeing Alert Service Bulletin 747-57A2247, Revision 3, dated June 22, 1989. Accomplishment of these actions constitutes terminating action for the repetitive inspections required by paragraph A., above.

C. Within the next 36 months after the effective date of this AD, inspect the center wing fuel tank front spar and upper surface secondary fuel barrier for proper application, in accordance with Boeing Alert Service Bulletin 747-57A2247, Revision 3, dated June 22, 1989. If improper fuel barrier application is detected, repair prior to further flight, in accordance with the service bulletin.

D. Within 30 days after accomplishing the inspection required by paragraph C., above, submit a report of the complete description of findings of the inspections from which it is determined that the secondary fuel barrier is not properly applied to: Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, 17900 Pacific Highway South, C-68966, Seattle, Washington 98168; rapid fax: (206) 431-1913; telex 756366.

E. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concuror comment, and then send it to the Manager, Seattle Aircraft Certification Office.

F. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This amendment supersedes Amendment 39-5939, AD 88-11-11, which superseded telegraphic AD T88-08-51. This amendment (39-6609, AD 90-11-08) becomes effective on July 2, 1990.