Summary
The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), that is applicable to Pratt & Whitney (PW) model PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, and PW4650 turbofan engines. That AD currently requires interim actions to address engine takeoff power loss events until the high- pressure-compressor (HPC) case is redesigned and available for incorporation on the PW4000 engines. That amendment also requires on- wing Testing-21 to engines installed on Boeing 747 and MD-11 airplanes, and the installation of a new Ring Case Configuration (RCC) rear HPC on PW 4000 series engines installed in the Boeing fleet as terminating action to the requirements of that AD. This proposal is prompted by the development of an RCC rear HPC for PW4000 series turbofan engines installed in the Airbus fleet. The actions specified by this proposed AD are intended to prevent engine takeoff power losses due to HPC surge.