62-17-06 PRATT & WHITNEY: Amdt. 470 Part 507 Federal Register August 1, 1962. Applies to All JT3C-12 Turbojet Engines.
Compliance required as indicated.
To preclude fatigue cracking in the rear face of the P/N 359708 eighth stage compressor rotor disc, accomplish the following:
(a) For discs previously inspected by the procedure described in paragraph (c), reinspect in accordance with paragraph (c) every 90 hours' time in service from the last inspection.
(b) For discs not previously inspected by the procedure described in paragraph (c), inspect in accordance with paragraph (c) as follows:
(1) Inspect discs with 1,000 or more hours' time in service within the next 90 hours' time in service and every 90 hours' time in service thereafter.
(2) Inspect discs with less than 1,000 hours' time in service prior to the accumulation of 1,090 hours' time in service and every 90 hours' time in service thereafter.
(c) Incorporate an inspection hole and plugin the compressor case and eighth stage stator shroud in accordance with Pratt & Whitney Aircraft letter dated June 21, 1962, and its attached sketch number L-53852. Using an American Cystoscope Markers, Inc. Model B-175-AS-15 or FAA approved equivalent viewing instrument inserted through this hole, inspect each eighth stage compressor rotor disc rear blade dovetail area and the entire circumferential area of the eighth stage disc spacer for possible cracks. If any crack indications are found, remove the engine prior to further flight and disassemble for confirmation of the indications. Replace cracked discs.
(d) Remove all eighth stage compressor rotor discs P/N 359708 from further service after 4,800 hours' time in service.
(e) Upon request of the operator, an FAA Maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Eastern Region, may adjust the repetitive inspection intervals specified in this AD to permit complianceat an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator.
(Pratt & Whitney Aircraft telegraphic message dated June 13, 1962, to Eastern Air Lines and Pratt & Whitney Aircraft letter dated June 21, 1962, and attached sketch L-53852 to Eastern Air Lines covers the same subject.)
This directive effective August 1, 1962.
Revised February 20, 1963.