Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series Turbofan Engines; Correction

This document makes a correction to Airworthiness Directive (AD) 99-20-04 applicable to certain Pratt & Whitney (PW) JT9D series turbofan engines that was published in the Federal Register on September 24, 1999 (64 FR 51683). The final rule inadvertently references HPC disk fracture instead of HPT disk fracture and one service bulletin (SB) reference in the compliance section is incorrect. This document corrects those references. The Compliance section in the final rule was inadvertently changed to incorporate the compliance requirements used in a similar PW2000 Airworthiness Directive. The Compliance requirements were correctly published in the NPRM, but were published incorrectly in the Final Rule. This correction will reinstate the compliance requirements originally published in the NPRM, and as intended for the JT9D. In all other respects, the original document remains the same.