Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to certain models of Pratt & Whitney PW4000 series turbofan engines. This amendment requires operators to perform initial and repetitive inspections for cracking of high pressure compressor (HPC) front drum rotors based on cycle usage. This amendment also requires the removal from service of any cracked HPC front drum rotors. This amendment is prompted by reports that 11 HPC drum rotors have been found cracked on the spacer surface between the sixth and seventh stage disks. The actions specified by this AD are intended to detect premature cracking of the HPC drum rotor that could result in an uncontained engine failure and damage to the airplane.