71-02-02: Twelfth Stage Compressor Rotor Disc

71-02-02 PRATT & WHITNEY: Amdt. 39-1143 as amended by Amendment 39-1201. Applies to all Pratt & Whitney Aircraft JT4A series turbojet engines which incorporate the following serial number 12th stage compressor rotor disc part number 360112 1F-6145 3F-8849 4F-3831 4F-8300 5F-8122 1F-6150 3F-8850 4F-4569 4F-8301 5F-8123 1F-6151 through 4F-4570 5F-8342 2F-2758 3F-8855 4F-4642 4F-8458 5F-8346 2F-2759 4F-4643 5F-6445 5F-8405 2F-2764 3F-8856 4F-4645 5F-6446 5F-8510 2F-3781 3F-8920 4F-4648 5F-6447 5F-8512 3F-8921 5F-6449 2F-3785 3F-8923 4F-4747 5F-6452 5F-8522 2F-3788 3F-8924 4F-4748 5F-7606 5F-8529 2F-3926 3F-8926 4F-4749 5F-7748 5F-8589 2F-3927 3F-8927 4F-4750 5F-7749 through 3F-8928 4F-4752 5F-7835 2F-3933 3F-9114 4F-4968 5F-7837 2F-9674 3F-9115 4F-5029 5F-7838 2F-9675 3F-9116 through 5F-7839 2F-9676 4F-0454 4F-5035 5F-7840 2F-9677 4F-0461 4F-50595F-7867 3F-0551 4F-0465 through 5F-7872 through 4F-0467 4F-5063 5F-7875 3F-0558 4F-0471 4F-5087 5F-7985 4F-0473 4F-5089 5F-7987 3F-0559 4F-0475 4F-5090 5F-8031 3F-0560 4F-0477 4F-5091 5F-8032 3F-0563 4F-3606 5F-8035 4F-3690 4F-5092 4F-3692 through 5F-8039 4F-5099 5F-8042 4F-3699 5F-8119 4F-3700 4F-3828 4F-3830 Compliance required as indicated. To preclude twelfth stage compressor rotor disc failure as the result of suspected material deficiency, accomplish the following: (1) For all the previously listed serial number twelfth stage compressor rotor discs: a. With 5000 cycles or more in service within the next 25 cycles in service after the effective date of this AD replace the suspect serial number disc. b. With 5000 cycles or less in service prior to the accumulation of 5025 cycles in service replace the suspect serial number disc. (2)Upon submission of substantiating data by an owner or operator through an FAA Maintenance Inspector, the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may adjust the compliance time. Amendment 39-1143 was effective January 14, 1971 and was effective as to all recipients of the telegram dated 10 December 1970 which contained this airworthiness directive. This Amendment 39-1201 is effective May 4, 1971.