AD 89-09-03

89-09-03 BOEING: Amendment 39-6184. Applicability: Model 737 airplanes, line numbers 001 through 291, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent decompression of the airplane, accomplish the following:

A. In accordance with the schedule set forth in paragraph B. of this AD:

1. Accomplish the terminating repair at all lap joints between BS 259 and BS 1016, which includes replacing all upper row fasteners with standard protruding head solid fasteners and assuring the tearstraps are functional 2 bays above and 1 bay below each lap joint, by the use of mechanical fasteners where disbonding of the tearstraps has occurred, in accordance with Boeing Alert Service Bulletin 737-53A1039, Revision 4, dated April 14, 1988.

2. Accomplish the preventative modification as described in Boeing Service Bulletin 737-53-1089, Revision 1, dated October 13, 1988, along S-17, using standard protruding head solid fasteners and assure the tearstraps are functional 1 bay above and below S-17, by the use of mechanical fasteners where disbonding of the tearstraps has occurred, in accordance with the Structural Repair Manual.

B. Airplanes are to be modified as required by paragraph A., above, in accordance with the following times after the effective date of this AD:

1. For fuselage structure between BS 360 and BS 1016:

Number of landings on effective date of this AD Modify within the next: 70,000 or more 6 months 60,000 - 69,999 12 months 50,000 - 59,999 18 months 40,000 - 49,999 24 months less than 40,000 36 months

2. For fuselage structure between BS 259 and BS 360, accomplish the modifications prior to a. or b., below, whichever occurs later:

a. the accumulation of 80,000 flight cycles or 4 years after the effective date of this AD, whichever occurs first; or

b. one year after the effective date of this AD.

C. For airplanes on which the procedure described in paragraph A.1., above, has been accomplished in accordance with Part IV, A.2, of Boeing Alert Service Bulletin 737-53A1039, Revision 4, dated April 14, 1988, within 15 months after accomplishment, or within 6 months after the effective date of this AD, whichever occurs later, perform an external visual inspection of the skin for corrosion and delamination at all lap joints in accordance with that service bulletin. If corrosion is found, prior to further flight, perform a low frequency eddy current inspection of the entire length of the affected panel to determine material loss. If cracks are found, prior to further flight, perform a high frequency eddy current inspection of the entire length of the affected skin panel for cracks in accordance with the service bulletin. Repair cracks, corrosion, and delamination, prior to further flight (except as permitted by paragraph D., below), in accordance with the service bulletin. Inspections are to continue at intervals not to exceed 15 months.

D. If corrosion found as a result of the external inspection does not exceed 10 percent of the skin thickness, reinspect for corrosion in accordance with paragraph C., above, at intervals not to exceed 2,250 cycles or 6 months, whichever occurs first, until a repair is accomplished. If such corrosion exceeds 10 percent of skin thickness or if cracking is found, repair prior to further flight, in accordance with Boeing Alert Service Bulletin 737-53A1039, Revision 4, dated April 14, 1988. Following such repair, resume inspections in accordance with paragraph C., above.

E. Accomplishment of the requirements of this AD constitutes terminating action for the requirements of AD 88-22-11, Amendment 39-6059, and is equivalent to the terminating modification therein. Any alternate means of compliance issued for that amendment are considered approved for this amendment.

F. 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 may add any comments and then send it to the Manager, Seattle Aircraft Certification Office.

G. 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, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington.

This amendment (39-6184, AD 89-09-03) becomes effective on May 19, 1989.