AD 75-01-01

75-01-01 PRATT & WHITNEY AIRCRAFT: Amendment 39-2055 as amended by Amendment 39-2358. Applies to all Pratt & Whitney JT8D-1, -1A, -7, and -7A model turbofan engines.

Compliance required as indicated.

To prevent failure of the low turbine shaft spline accomplish the following:

1. Remove from service thin wall low turbine shafts not incorporating Pratt & Whitney Aircraft Service Bulletin 2452 (P/Ns 479796, 493412, 511215, 524958, 528365, 528366, 538951, 540354, 540355, 540452, 562503, 562504, 576305, 576312, 576313, 576314, and 587879) prior to the accumulation of 6700 cycles in service since new, or within the next 2000 cycles in service after January 8, 1975, whichever is later.

2. Inspect thin wall low turbine shafts incorporating Pratt & Whitney Aircraft Service Bulletin 2452 (P/Ns 540354-S/B2452, 540355-S/B2452, 540452-S/B2452, 676276, 676277, 676278, 676279, 676280, 676282, 676283, 676284, 676285, 676286, and 676287) for cracked splines in accordance with thePratt & Whitney Service Bulletin 2452, Revision 10, or later FAA approved revision, or equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA, New England Region, prior to the accumulation of 6700 cycles in service since last inspection or within the next 2000 cycles in service after January 8, 1975, whichever is later, unless already accomplished in accordance with Pratt & Whitney Service Bulletin No. 2452, Revision No. 10, or in accordance with the eddy current inspection of Pratt & Whitney Service Bulletin No. 2452, Revision Nos. 5 thru 9. Inspect thereafter at intervals not to exceed 6700 cycles in service from the last inspection. Remove shafts with cracks from service before further flight.

3. Inspect all No. 2 compressor hub splines plated per Pratt & Whitney Service Bulletins 2964 and 4193, in accordance with Pratt & Whitney Alert Service Bulletin 4357, Paragraphs IV.D.2 and IV.D.3, or later FAA approved revision, as applicable, when the low turbine shafts are removed or inspected in accordance with Paragraph 1 or 2 above. Remove hubs with plate peeling from service before further flight.

4. Inspect nonplated titanium No. 2 compressor hub splines, run with low turbine shafts requiring inspection under Paragraphs 1 or 2 of this AD, for taper wear in accordance with Pratt & Whitney JT8D manual, P/N 481672, Revision 76, Section 72-33-6, or later FAA approved revision, prior to the accumulation of 6700 cycles in service or within the next 2000 cycles in service after January 8, 1975, whichever is later, unless already accomplished. Inspect thereafter at intervals not to exceed 6700 cycles in service since last inspection. Remove hubs with taper wear in excess of .010 inch from service before further flight.

The manufacturer's service bulletins identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Pratt & Whitney Aircraft, 400 Main Street, East Hartford, Ct. 06108. These documents may also be examined at the Office of the Regional Counsel, Federal Aviation Administration, New England Region, 12 New England Executive Park, Burlington, MA 01803, and at Federal Aviation Administration Headquarters, 800 Independence Avenue, S.W., Washington, D.C. 20591. A historical file on this AD which includes the incorporated material in full is maintained by the Federal Aviation Administration at its headquarters in Washington D.C., and at the New England Regional Office in Burlington, MA.

Upon submission of substantiating data through an FAA maintenance inspector by an owner or operator, the Chief, Engineering and Manufacturing Branch, FAA, New England Region, may adjust the compliance time.

NOTE: Pratt & Whitney Alert Service Bulletin 4357 pertains to this subject.

Amendment 39-2055 became effective January 8, 1975.

This amendment 39-2358 becomes effective September 17, 1975.