Summary
We propose to adopt a new airworthiness directive (AD) for certain PW4000 series turbofan engines. This proposed AD was prompted by reports of 3rd and 4th stage vane fractures in the low pressure turbine (LPT) of certain PW4000-94'' and PW4000-100'' turbofan engines. These fractures caused an uncontained engine failure, an LPT case puncture, and multiple in flight shutdowns. We are proposing this AD to prevent 3rd and 4th stage vane fractures in the LPT, which could damage the LPT rotor and lead to an uncontained engine failure and damage to the airplane.