Airworthiness Directive · Amendment 39-21470 · Turbine engine compressor section
Pratt & Whitney Division Turbofan Engines
Superseded. A later AD replaced this one: AD 2022-06-09. Comply with the one in force.
This AD applies to Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 model turbofan engines, with a 1st-stage low-pressure compressor (LPC) blade, with part number 52A241, 55A801, 55A801-001, 55A901, 55A901-001, 56A201, 56A201-001, or 56A221, installed.
The FAA is adopting a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 model turbofan engines. This 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 AD requires performing a thermal acoustic image (TAI) inspection for cracks in certain 1st-stage LPC blades and removal of those blades that fail inspection. The FAA previously sent an emergency AD to all known U.S. owners and operators of these engines and is now issuing this AD to address the unsafe condition on these products.
(1) Before further flight, perform a thermal acoustic image (TAI) inspection of the 1st-stage LPC blades for cracks using a method approved by the FAA.
Note 1 to paragraph (g)(1): Vendors that have an FAA-approved TAI inspection are listed in the Vendor Services Section of Pratt & Whitney Alert Service Bulletin PW4G-112-A72-268, Revision No. 7, dated September 6, 2018.
(2) If any 1st-stage LPC blade fails the inspection required by paragraph (g)(1) of this AD, remove the blade from service and replace with a part eligible for installation before further flight.
For the purpose of this AD, a “part eligible for installation” is a 1st-stage LPC blade that passed the inspection required by paragraph (g)(1) of this AD.
