AD 85-03-06 R1

85-03-06 R1 BOEING: Amendment 39-4998 as amended by Amendment 39-5205. Applies to Model 737 series airplanes certificated in all categories listed in Boeing Service Bulletin 737-53- 1031, Revision 3, dated October 28, 1983. To prevent rapid decompression resulting from undetected cracking of the wing-to-body drag angle, accomplish the following (unless previously accomplished) prior to the accumulation of 8,000 landings on Group I airplanes, or 35,000 landings on Group II airplanes, or within 1 year or 4,000 landings from the effective date of this AD, whichever occurs later:

A. Visually inspect the upper drag angles for cracks in accordance with the Flight Safety Addendum of Boeing Service Bulletin 737-53-1031, Revision 3, or later FAA approved revisions. Repeat the visual inspections at intervals not to exceed 4,000 landings.

B. If cracks are found, replace cracked parts with new aluminum parts and continue the inspections of paragraph A., above, or modify in accordance with the Accomplishment Instructions in Boeing Service Bulletin 737-53-1031, Revision 1, or later FAA-approved revisions.

C. Modification of airplanes in accordance with Accomplishment Instructions of Boeing Service Bulletin 737-53-1031, Revision 1, or later FAA-approved revisions, constitutes terminating action for this AD.

D. Airplanes may be flown to a maintenance base for drag angle replacement or modification in accordance with FAR 21.197 and 21.199 with prior approval of the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

E. For purposes of complying with the AD, subject to acceptance by the assigned FAA Principal Maintenance Inspector, the number of landings may be determined by dividing each airplane's time in service by the operator's fleet average time from takeoff to landing for the airplane type.

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

G. Upon request by the operator, an FAA Principal Maintenance Inspector, subject to prior approval by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, may adjust the repetitive inspection intervals in this AD, if the request contains substantiating data to justify the increase for the operator.

All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the Boeing Commercial Airplane Company, 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 the Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

Amendment 39-4998 became effective March 11, 1985. This Amendment 39-5205 becomes effective February 3, 1986.