91-05-15 BRITISH AEROSPACE: Amendment 39-6908. Docket No. 90-NM-173-AD.
Applicability: All Model ATP series airplanes, certificated in any category.
Compliance: Required as indicated, unless previously accomplished.
To detect cracks in the engine jet pipes, accomplish the following:
A. For airplanes in Pre-Modification 35140A configuration: Prior to the accumulation of 500 hours time-in-service since new, or within 50 hours time-in-service after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 250 hours time-in-service, perform a detailed visual inspection of the engine jet pipe on the right and left engine, in accordance with the Accomplishment Instructions in British Aerospace Service Bulletin ATP-78-1, Revision 3, dated August 1, 1990.
B. For airplanes in Post-Modification 35140A configuration: Prior to the accumulation of 3,000 hours time-in-service since new, or within 50 hours time-in-service afterthe effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 1,500 hours time-in-service, perform a detailed visual inspection of the engine jet pipe on the right and left engine, in accordance with the Accomplishment Instructions in British Aerospace Service Bulletin ATP-78-1, Revision 3, dated August 1, 1990.
C. If cracks are found in the aft jet pipe assembly, prior to further flight:
1. Replace the assembly with a serviceable unit; or
2. If cracks measuring less than 1.75 inches are found at the ends of the spacer channels, repair in accordance with British Aerospace Service Bulletin ATP-78-1, Revision 3, dated August 1, 1990; or
3. If cracks are found at any other location, repair in a manner approved by the Manager, Standardization Branch, ANM-113, Transport Airplane Directorate.
Following repair or replacement, the inspections specified in paragraphs A. and B. of this AD are still required.
D. If cracks are found in the forward jet pipe assembly, prior to further flight, replace the assembly with a serviceable unit, or repair in a manner approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Following repair, the inspections specified in paragraph A. and B. of this AD are still required.
E. Within 12 months after the effective date of this AD, replace the aft jet pipe, Part Number JD 780J0009-000, with an improved aft jet pipe having Part Number JD780J0009-002 or -004, in accordance with British Aerospace Service Bulletin ATP-78-2, dated April 10, 1990, or ATP-78-2, Revision 1, dated November 12, 1990.
1. Following replacement, perform repetitive detailed visual inspections at intervals not to exceed 1,500 hours time-in-service, in accordance with the service bulletin.
2. If cracks are found, prior to further flight replace the aft jet pipe with a service-able part in accordance with the service bulletin, or repair in a manner approved by the Manager, Standardization Branch, ANM-113, Transport Airplane Directorate.
F. An alternate means 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 submitted directly to the Manager, Standardization Branch, ANM-113, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Manager, Standardization Branch, ANM-113.
G. 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.
All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to British Aerospace, PLC, Librarian for Service Bulletins, Dulles International Airport, Washington, D.C. 20041-0414. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington.
This amendment (39-6908, AD 91-05-15) becomes effective on March 29, 1991.