Summary
We propose to adopt a new airworthiness directive (AD) for all Pratt & Whitney PW4050, PW4052, PW4056, PW4056(-3), PW4156, PW4060, PW4060(- 3), PW4060A, PW4152, PW4152(-3), PW4156A, PW4158, PW4158(-3), PW4460, PW4460(-3), PW4462, and PW4462(-3) turbofan engines. This proposed AD was prompted by reports of five engine in-flight shutdowns and seven unplanned engine removals. This proposed AD would require inspections, cleaning, and engine modifications to address coking in the No. 4 bearing compartment and oil pressure and scavenge tubes. We are proposing this AD to prevent an engine fire, a fractured fan drive shaft, and damage to the airplane.