AD 84-20-03 R1

84-20-03 R1 BOEING: Amendment 39-4923 as amended by Amendment 39-5183. Applies to Model 737 series airplanes, certificated in any category, as listed in Boeing Service Bulletin 737- 53-1075, Revision 1, dated September 2, 1983, with more than 20,000 flight hours time in service or 7 years since manufacture, whichever occurs first. Compliance is required as indicated. To ensure the continuing structural integrity of the aft pressure bulkhead, accomplish the following:

A. Within 120 days after the effective date of this AD, unless already accomplished within the last 21 months, visually inspect the B.S. 1016 pressure bulkhead for cracks and corrosion in accordance with Boeing Service Bulletin 737-53-1075, Revision 1, dated September 2, 1983, or later FAA approved revisions. Remove any obstruction to the drain hole in the frame chord and replace any deteriorated leveling compound as noted in the service bulletin. Treat the area of inspection with corrosion inhibitor, BMS 3-23, or equivalent.

B. Accomplish the drain hole enlargement specified in the service bulletin, within one year following the effective date of this amendment.

C. If cracking or corrosion is found, prior to further flight, repair in accordance with (1) Boeing Service Bulletin 737-53-1075, Revision 1, dated September 2, 1983, or (2) a method approved by the Manager, Seattle Aircraft Certification Office, Northwest Mountain Region, Seattle, Washington.

D. Repeat the visual inspections and corrosion inhibitor treatment of paragraph A, above, at intervals not to exceed 2 years time in service.

E. Aircraft may be ferried to a maintenance base for repair in accordance with FAR 21.197 and 21.199.

F. Alternate means of compliance which provide an equivalent level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, Northwest Mountain Region, Seattle, Washington.

G. Upon request of the operator, an FAA Maintenance Inspector, subject to prior approval of the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of an operator, if the request contains substantiating data to justify the adjustment period.

All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Company, P. O. Box 3707, Seattle, Washington 98124. These documents may also be examined at FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington.

Amendment 39-4923 became effective November 5, 1984. This Amendment 39-5183 becomes effective January 20, 1986.