AD 70-25-08

70-25-08 PRATT & WHITNEY: Amdt. 39-1084. Applies to all Pratt & Whitney aircraft JT8D series turbofan engines which incorporate Part Number 500507 seventh stage compressor rotor disc with serial numbers listed in Pratt & Whitney Service Bulletin No. 2817, Rev. No. 1, dated 18 September 1970.

Compliance required as indicated after the effective date of this airworthiness directive unless already accomplished.

To preclude seventh stage compressor rotor disc failures as the result of suspected material deficiency, accomplish the following:

1. Replace discs with 2700 cycles or more in service within the next 30 cycles in service.

2. Replace discs with 2300 cycles, but less than 2700 cycles in service, within the next 100 cycles in service, but prior to accumulation of 2730 cycles.

3. Replace discs with 2000 cycles, but less than 2300 cycles in service, within the next 300 cycles in service, but prior to the accumulation of 2400 cycles.

4. Replace discs with less than 2000 cycles in service prior to the accumulation of 2300 cycles.

The manufacturer's Service Bulletin identified and described in this directive is 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 this document from the manufacturer may obtain copies upon request from Pratt & Whitney Aircraft Division of United Aircraft Corporation, East Hartford, Conn. This document may also be examined at the FAA, Eastern Region, Federal Building, J. F. Kennedy International Airport, Jamaica, N.Y., at the FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C.

A historical file on this AD which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D.C., and in the Eastern Region.

This amendment is effective December 15, 1970 and was effective October 2, 1970, for all recipients of the telegram dated October 2, 1970, which contained this amendment.