AD 78-22-10

78-22-10 AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Amendment 39-3335. Applies to AiResearch Model TFE 731 - 2, - 3 and - 3R engines of the serial numbers listed certificated in all categories, equipped with low pressure rotor thrust ball bearings (number three bearings), Part No. 358736-2, manufactured by SNFA Bearing Corporation.

This AD applies to the following listed engine serial numbers:

ENGINE SERIAL NUMBERS

74606 77239 73431 73430 73433 74609 77240 80193 84121 74614 74604 74590 74615 74618 78227 77238 77241 73432 75294 77245 74591 74602 84123 84122 77243 84111 74587 76113 84120 78229 74605 75282 74616 75286 78226 74603 75279 74617 76112 77247 74589 75281 75285 77244 74620 75191 74419 77246 74101C 73299 74619 78151 73215 74624 73221 75175 74623 78129 75178 73111 74224 74508 75280 73209

Compliance required as indicated.

To prevent failure of the lowpressure rotor thrust ball bearing which could result in an immediate inflight shutdown of the engine, accomplish the following unless already accomplished.

(a) Before further flight after receipt of this AD, remove from the engine and visually inspect the inner face of both halves of the split inner race of the low pressure rotor thrust ball bearing (number three bearing), Part No. 358736-2, to determine the presence of the six radial oil lubrication grooves.

(1) If the inner face halves of the bearing inner race do not have a total of six radial oil lubrication grooves, the bearing should be removed and replaced with a conforming part which does have the six oil lubrication grooves in the inner face halves of the split inner race.

NOTE: There is an optional method of manufacturing raceway oil slots in low pressure rotor thrust ball bearing, Part Number 358736-2. Three raceway oil slots may be machined into each inner face of both halves of the split inner race or six raceway oil slots may be machined into the inner face of the forward inner race. Both options are acceptable.

NOTE: Bearings found to be improperly manufactured should be returned to the AiResearch Manufacturing Company of Arizona.

(2) If the bearing inner race halves do have the six radial oil lubrication grooves, the bearing may be reassembled, reinstalled and returned to service provided it is found to be otherwise serviceable.

(b) Special flight permits may be issued per FAR 21.197 and 21.199 to authorize operation of aircraft to a base where this inspection required by this AD may be performed provided that there is not more than one affected serial numbered engine listed in this AD installed on the aircraft.

(c) Equivalent inspection procedures and repairs may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region.

This amendment is effective November 13, 1978 and was effective upon receipt for all recipients of the priority mail letter dated September 22, 1978, which contained this amendment.