Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), applicable to certain Pratt & Whitney PW4000 series turbofan engines, that requires fluorescent penetrant and eddy current inspections of 2nd stage high pressure turbine (HPT) rotating airseals for cracks, removal from service of cracked parts, incorporation of improved 2nd stage HPT rotating airseals, and modification of 2nd stage ring segments and vane clusters to increase cooling flow and reduce stress as terminating action to the inspection requirements. This amendment is prompted by reports of 2nd stage HPT rotating airseal cracking. The actions specified by this AD are intended to prevent 2nd stage HPT rotating airseal cracking, which could result in an uncontained engine failure and damage to the aircraft.