62-09-04 PRATT & WHITNEY: Amdt. 424 Part 507 Federal Register April 19, 1962. Applies to All JT3C- 7 and JT3C-12 Turbojet Engines.
Compliance required as indicated.
Because of fatigue cracking which has occurred in the dovetail attachment of P/N 359403 third stage compressor rotor blades the following is required:
(a) For blades previously inspected by the procedure described in paragraph (c), reinspect in accordance with paragraph (c) as follows:
(1) Inspect blades which have accumulated 300 hours or less time in service since the last inspection, prior to the accumulation of 350 hours' time in service and thereafter within each 350 hours' time in service.
(2) Inspect blades which have accumulated more than 300 hours' time in service since the last inspection, within the next 50-hours' time in service and thereafter within each 350 hours' time in service.
(b) For blades not previously inspected by the procedure described in paragraph (c), inspect in accordance with paragraph (c) as follows:
(1) Inspect blades with 700 or more total hours' time in service within the next 50 hours' time in service and every 350 hours' time in service thereafter.
(2) Inspect blades with less than 700 total hours' time in service prior to the accumulation of 750 hours' time in service and every 350 hours' time in service thereafter.
(c) Incorporate an inspection hole and plug in the compressor case and third stage stator shroud in accordance with Pratt & Whitney Aircraft (R.G.B.) letter dated February 24, 1962, and its attached sketch to all JT3C-7 and JT3C-12 operators. Using an American Cystoscope Makers, Inc. Model B35A-12 or equivalent viewing instrument inserted through this hole, inspect each third stage blade dovetail attachment for possible cracking in both flanks, rear radius, and rear face. If any crack indications are found, remove the engine prior to further flight and disassemble for confirmation of the indications. Replace any cracked blades.
(d) 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 compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator.
(Pratt & Whitney Aircraft (R.G.B.) letter dated February 24, 1962, and attached sketch, to all JT3C-7 and JT3C-12 operators, and P&WA telegraphic message dated February 28, 1962, to all JT3C-7 and JT3C-12 operators, covers the same subject.)
This directive effective April 19, 1962.