Airworthiness Directives; Pratt & Whitney Canada (PWC) Model PW305 and PW305A Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to Pratt & Whitney Canada (PWC) Models PW305 and PW305A turbofan engines, that requires removing stage 4 low pressure turbine (LPT) disks from service before exceeding new, lower cyclic life limits. This amendment is prompted by the results of a spin pit test analysis which indicate that the stage 4 LPT disk does not have full published life. The actions specified by this AD are intended to prevent LPT disk failure resulting from premature cracking of the LPT disks, which could result in an uncontained engine failure and damage to the airplane.