AD #: 2021-05-51 Prompted By An In-Flight Failure Of A 1st-Stage LPC Blade On A PW4077

An Emergency Airworthiness Directive (AD) 2021-05-51 has been sent to owners and operators of Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 model turbofan engines.

This emergency AD was prompted by the in-flight failure of a 1st-stage low-pressure compressor (LPC) blade on a PW4077 model turbofan engine resulting in an engine fire during flight. This condition, if not addressed, could result in 1st-stage LPC blade release, damage to the engine, and damage to the airplane.

The FAA reviewed Pratt & Whitney Alert Service Bulletin (ASB) PW4G-112-A72-268, Revision No. 7, dated September 6, 2018. This ASB specifies procedures for performing thermal acoustic image (TAI) inspections of 1st-stage LPC blades.

FAA’s Determination: The FAA is issuing this AD because the agency has determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

AD Requirements: This AD requires performing a TAI inspection for cracks in certain 1st-stage LPC blades and removal of those blades that fail inspection.

Interim Action: The FAA considers this AD to be an interim action. The FAA anticipates that further AD action will follow.

FMI: www.regulations.gov