AD 87-16-13

87-16-13 BOEING: Amendment 39-5702. Applies to Model 747 series airplanes, as listed in Boeing Alert Service Bulletin 747-53A2279, dated January 15, 1987, certificated in any category. Compliance required as indicated, unless previously accomplished.

To detect disbonding of the upper body tear straps in body section 46, accomplish the following, unless already accomplished:

A. Within 250 landings after the effective date of this AD for airplanes line number 1 through 230, and within 750 landings after the effective date of this AD, for airplanes line number 231 through 349, perform an ultrasonic inspection of tear straps for disbonding in accordance with Boeing Alert Service Bulletin 747-53A2279, Revision 1, dated May 7, 1987, or later FAA-approved revisions.

B. If no evidence of unbonded areas are found, reinspect those areas at intervals not to exceed 6 years.

C. If evidence of unbonded areas is found, and the unbonded area between any two adjacent stringersdoes not exceed 60 percent of the total tear strap area between these stringers, reinspect those areas at intervals not to exceed the limits allowed by the chart in Figure 2 or 4, as appropriate, of Boeing Alert Service Bulletin 747-53A2279, Revision 1, dated May 7, 1987, or later FAA-approved revisions.

D. If evidence of unbonded areas is found, and the unbonded area between any two adjacent stringers exceeds 60 percent of the total tear strap area between these stringers, repair those areas prior to further flight in accordance with Boeing Alert Service Bulletin 747-53A2279, Revision 1, dated May 7, 1987, or later FAA-approved revisions. If blind fasteners are used, visually reinspect installation at intervals not to exceed 1,000 landings for loose or missing fasteners, cracks, or corrosion.

E. Terminating action for the inspections required by this AD is the installation of solid fasteners at all affected tear strap locations in accordance with Boeing Alert Service Bulletin 747-53A2279, Revision 1, dated May 7, 1987, or later FAA-approved revisions.

F. For the purpose of complying with this AD, the number of landings may be determined to equal the number of pressurization cycles where the cabin pressure differential was greater than 2.0 PSI.

G. An alternate means of compliance or adjustment of the compliance time, which provide an acceptable level of safety and which has the concurrence of an FAA Principal Maintenance Inspector, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

H. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by 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 the Boeing Commercial Airplane Company, P.O. Box3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This amendment, 39-5702, becomes effective September 13, 1987.