91-21-04 BRITISH AEROSPACE: Amendment 39-8051. Docket No. 91-NM-26-AD.
Applicability: Model BAC 1-11 200 and 400 series airplanes, certificated in any category.
Compliance: Required as indicated, unless previously accomplished.
To prevent degradation in the structural capabilities of the pressure cabin on affected airplanes, accomplish the following:
A. For airplanes operating at a maximum cabin differential pressure of 7.5 pounds per square inch (psi), as specified in British Aerospace Alert Service Bulletin 53-A-PM5991, Issue 1, dated September 5, 1990: At or prior to the accumulation of 33,000 landings or within 4,000 landings after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 8,000 landings, accomplish the following:
1. Perform a dye penetrant inspection to detect cracks in the left and right machined attachment angles, Part Number AB27-7761/2, in accordance with paragraph 2.1.3 of the service bulletin.
2. Perform a visual inspection to detect cracks in the top flange of the longitudinal boom of the left and right outboard auxiliary beam, in accordance with paragraph 2.1.4 of the service bulletin.
B. For airplanes operating at a cabin pressure in excess of 7.5 psi up to a maximum of 8.2 psi, as specified in British Aerospace Alert Service Bulletin 53-A-PM5991, Issue 1, dated September 5, 1990: At or prior to the accumulation of 22,000 landings or within 3,000 landings after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 5,000 landings, accomplish the following:
1. Perform a dye penetrant inspection to detect cracks in the left and right machined attachment angles, Part Number AB27-7761/2, in accordance with paragraph 2.2.3 of the service bulletin.
2. Perform a visual inspection to detect cracks in the top flange of the longitudinal boom of the left and right outboard auxiliary beam, in accordance with paragraph 2.2.4 of the service bulletin.
C. If defects are found during the inspections required by this AD, prior to further flight, either replace the cracked structure with serviceable parts of the same part number; or repair in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Northwest Mountain Region. Following repair or replacement, repeat the inspections required by paragraphs A. and B. of this AD at the specified intervals.
D. All machined attachment angles having Part Number AB27-7761/2 must be replaced with a new part of the same part number prior to the accumulation of 85,000 landings since new and thereafter at intervals not to exceed 85,000 landings.
E. 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, Standardization Branch, ANM-113, 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, Standardization Branch, ANM-113.
F. 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.
G. The inspection, repair, and replacement requirements shall be done in accordance with British Aerospace Alert Service Bulletin 53-A-PM5991, Issue 1, dated September 5, 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 British Aerospace, PLC, Librarian for Service Bulletins, P.O. Box 17414, Dulles International Airport, Washington, D.C. 20041-0414. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington; or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C.This amendment (39-8051, AD 91-21-04) becomes effective on November 19, 1991.