83-04-06 BRITISH AEROSPACE, AIRCRAFT GROUP, SCOTTISH DIVISION: Amendment 39-4574. Applies to Model B.121 series airplanes (all serial numbers) certificated in any category.
COMPLIANCE: Required as indicated unless already accomplished.
To preclude failure of the engine mounting structure, within the next 100 hours time-in- service after the effective date of this AD or upon accumulating 1000 hours time-in-service, whichever occurs later, and thereafter at intervals not to exceed 50 hours time-in-service from the last inspection, accomplish the following:
(a) Visually inspect the engine mounting structure for cracks in accordance with the "Action" Section of British Aerospace, Aircraft Group, Scottish Division, Service Bulletin Number B121/81, Issue 2, dated December 3, 1980, or an FAA approved equivalent.
(b) If a crack is found in the engine mounting structure, prior to further flight, repair or replace the engine mount in accordance with instructions providedby British Aerospace, Dulles International Airport, Washington, D.C., phone 703-435-9100, and approved by the Manager, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East Office, FAA, c/o American Embassy, Brussels, Belgium.
(c) The intervals between the repetitive inspections required by this AD may be adjusted up to 10 percent of the specified interval to allow accomplishing these inspections concurrent with other scheduled maintenance of the airplane.
(d) Operators who have not kept records of hours time-in-service of the engine mounting structure must substitute airplane hours time-in-service in lieu thereof.
(e) Aircraft may be flown in accordance with Federal Aviation Regulation 21.197 to a location where this AD can be accomplished.
(f) An equivalent method of compliance with this AD if used must be approved by the Manager, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East Office, FAA, c/o American Embassy, 1000 Brussels, Belgium.
This amendment becomes effective on March 7, 1983.