AD 71-17-06

71-17-06 PRATT & WHITNEY AIRCRAFT: Amendment 39-1262. Applies to all Pratt & Whitney Aircraft JT12A-6, JT12A-6A, JT12A-8, and J60P-5B Turbojet engines.

Compliance required as indicated.

To prevent cracking and possible failure of stage 2, 3, 7 and 8 compressor rotor discs of life limits on these parts have been reduced below the figures currently approved. Unless already accomplished, remove from service stage 2, 3, 7 and 8 compressor rotor discs prior to reaching the revised life limit below or, within the next 30 cycles in service after the effective date of this airworthiness directive, whichever comes later.

Part Number Previous Life Limit Cycles Revised Life Limit Cycles 406302 8000 6000 541902 8000 6000 406203 7500 4000 541903 7500 4000 426107 4000 2500 541907 4000 2500 406208 8000 5000 541908 8000 5000

NOTE: (The disc hour life limit as specified in Pratt & Whitney Aircraft Overhaul Manual Part No. 435108 Table of Limits Section XI has not been revised.)

(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.)

NOTE: P&WA Telegram PSE/AMG/1-7-13-1 covers this same subject.

This amendment is effective August 17, 1971.