Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney PW4000 series turbofan engines. This proposal would require 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 proposal is prompted by reports of 2nd stage HPT rotating airseal cracking. The actions specified by the proposed AD are intended to prevent 2nd stage HPT rotating airseal cracking, which could result in an uncontained engine failure and damage to the aircraft.