AD 71-20-01 ACTIVE

71-20-01 BRITISH AIRCRAFT CORPORATION: Amendment 39-1293 as amended by Amendment 39-2275. Applies to Model BAC 1-11 200 and 400 series airplanes.

Compliance is required as indicated.

To prevent possible failures of the flap system secondary drive shafts at the trackside support bearing assemblies, accomplish the following at each bearing assembly (eight per airplane) which has not had British Aircraft Modification PM 4642 incorporated:

(a) For each bearing assembly, within the next 1,000 landings after the effective date of this AD, or before the accumulation of 4,000 landings, whichever occurs later, and thereafter at intervals not to exceed 750 landings from the last inspection, visually inspect the bearing assembly for end float in accordance with British Aircraft Corp. Model BAC 1-11 Alert Service Bulletin No. 27-A-PM 4642, Issue 2, dated July 14, 1972, or an FAA-approved equivalent.

(b) If the bearing assembly end float is found to exceed 0.050 inches during aninspection required by this AD and -

(1) The four alternate locking tabs have not been bent over, before further flight, except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be performed, comply with paragraph (c), (d), or (e).

(2) The four alternate tabs have been bent over, before further flight, except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be performed, comply with paragraph (d) or (e).

(c) Bend over the four alternate locking tabs of the affected bearing assembly in accordance with paragraph 2.1.3 of British Aircraft Corp. Model BAC 1-11 Alert Service Bulletin No. 27-A-PM 4642, Issue 2, dated July 14, 1972, or an FAA-approved equivalent. Repeat the inspection specified in paragraph (a) on the affected bearing assembly at intervals not to exceed 750 landings from the last inspection.

(d) Overhaul the affected bearing assembly by replacing the fork end, bushings, thrust washers, and retaining ring with serviceable parts of the same part number. Before the accumulation of a total of 4,000 landings on the overhauled bearing assembly and thereafter at intervals not to exceed 750 landings from the last inspection, repeat the inspection specified in paragraph (a).

(e) Replace the affected bearing assembly with a serviceable bearing assembly which has BAC Modification PM 4642 incorporated.

(f) Operators who have not kept records of the number of landings accumulated on individual bearing assemblies shall substitute airplane landings in lieu thereof.

(g) For the purpose 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 BAC 1-11 airplane.

(h) Upon request of the operator, an FAA Maintenance Inspector, subject to prior approval by the Chief, Aircraft Certification Staff, FAA Europe, Africa, and Middle East Region may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for that operator.

Amendment 39-1293 became effective October 15, 1971.

This amendment 39-2275 becomes effective August 25, 1975.