AD 86-12-05

86-12-05 BOEING: Amendment 39-5321. Applies to Model 737 series airplanes listed in Boeing Service Bulletin 737-55-1033, dated April 12, 1985, certificated in any category. To detect cracking in the horizontal stabilizer center section rear spar upper chord attach lugs, accomplish the following prior to the accumulation of 40,000 landings; or prior to the accumulation of 40,000 landings after a chord replacement or modification in accordance with Boeing Service bulletin 737-55-1033, Option I, dated April 12, 1985; or within 200 landings after the effective date of this AD; whichever occurs latest, unless accomplished within the last 5,500 landings.

A. Eddy current inspect the horizontal stabilizer center section rear spar upper chord attach lug for cracks in accordance with the Flight Safety Inspection Program specified in Boeing Service Bulletin 737-55-1033, dated April 12, 1985, or later FAA-approved revisions. Repeat at intervals not to exceed 5,700 landings.

B. Ifcracks are found, replace the horizontal stabilizer center section rear spar upper chord in accordance with Boeing Service Bulletin 737-55-1033, dated April 12, 1985, or later FAA-approved revisions. Resume the inspections required by paragraph A., above, prior to the accumulation of 40,000 landings after the chord replacement, or modification in accordance with Boeing Service Bulletin 737-55-1033, Option I, dated April 12, 1985.

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

D. 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.

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

All persons affected by this directive who have not already received the appropriate service bulletin 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 FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or the Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This amendment becomes effective June 30, 1986.