AD 91-14-21

91-14-21 BOEING: Amendment 39-7062. Docket No. 91-NM-33-AD. Supersedes AD 90-20-12.

Applicability: Model 757 series airplanes, listed in Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent failure of the fixed trailing edge upper panel support beam clips and consequent damage to airplane structure and hydraulic lines, accomplish the following:

A. For airplanes line numbers 1 through 140 and 151:

1. Prior to the accumulation of 600 total landings, or within the next 30 days after October 23, 1990, (the effective date of Amendment 39-6732, AD 90-20-12), whichever occurs later, unless previously accomplished within the last 600 landings, and thereafter at intervals not to exceed 600 landings, perform a detailed visual inspection for cracks in the fixed trailing edge upper panel support beam clips, in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990. Replace cracked clips with the newly designed clips in kit number 012N8660-1 or clips in kit number 012N8546-1 after modifying, in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990. Upon completion, this action terminates the inspections required above, for those clips replaced.

2. Within 3,000 landings after October 23, 1990, replace all affected clips with newly designed or modified clips and spacers, in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990. Accomplishment of this replacement constitutes terminating action for the inspection requirements of this AD.

B. For airplanes line numbers 141 through 150 and 152 through 163:

1. Prior to the accumulation of 600 total landings or within the next 30 days after the effective date of this amendment, whichever occurs later, unless previously accomplished within the last 600 landings, and thereafter at intervals not to exceed 600 landings, perform a detailed visual inspection for cracks in the fixed trailing edge upper panel support beam clips, in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990. Replace cracked clips with the newly designed clips in kit number 012N8660-1 or clips in kit number 012N8546-1 after modifying, in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990. Upon completion, this action terminates the inspections required above, for those clips replaced.

2. Within 3,000 landings after the effective date of this AD, replace all affected clips with newly designed or modified clips and spacers, in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990. Accomplishment of this replacement constitutes terminating action for the inspection requirements of this AD.

C. An alternative method 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 (ACO), FAA, Transport Airplane Directorate.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO.

D. 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.

E. The inspections and repairs shall be done in accordance with Boeing Service Bulletin 757-57-0027, Revision 1, dated March 15, 1990.

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue SW.,Renton, Washington, or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, D.C.

Airworthiness Directive 91-14-21, supersedes AD 90-20-12, Amendment 39-6732. This amendment (39-7062, AD 91-14-21) becomes effective on August 9, 1991.