Airworthiness Directives; Pratt & Whitney Canada Models PW306A and PW306B Turbofan Engines

This amendment adopts a new airworthiness directive (AD) that is applicable to Pratt & Whitney Canada (PWC) models PW306A and PW306B turbofan engines. This amendment requires removing compressor rotor 2nd, 3rd, and 4th stage drum assemblies and impellers from service before exceeding new, lower cyclic life limits. This amendment is prompted by the results of test analyses that indicate certain compressor rotor 2nd, 3rd, and 4th stage drum assemblies and impellers do not have full published life. The actions specified in this AD are intended to prevent premature cracking of compressor rotor 2nd, 3rd, and 4th stage drum assemblies and impellers which could result in an uncontained engine failure and damage to the airplane.