Airworthiness Directive · Amendment 39-19553 · Turbine engine compressor section
Pratt & Whitney Division (PW) Turbofan Engines
Superseded. A later AD replaced this one: AD 2022-06-09. Comply with the one in force.
This AD applies to all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines, with 1st-stage low-pressure compressor (LPC) blade, part numbers 52A241, 55A801, 55A801-001, 55A901, 55A901-001, 56A201, 56A201-001, or 56A221, installed.
We are adopting a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines. This AD was prompted by an in-flight failure of a 1st-stage low-pressure compressor (LPC) blade. This AD requires initial and repetitive thermal acoustic imaging (TAI) inspections for cracks in certain 1st-stage LPC blades and removal of those blades that fail inspection. We are issuing this AD to address the unsafe condition on these products.
(1) After the effective date of this AD, perform an initial thermal acoustic imaging (TAI) inspection of the 1st-stage LPC blades as follows:
(i) For 1st-stage LPC blades that have accumulated fewer than 6,500 cycles since new (CSN), perform a TAI inspection the next time the engine is separated at the M-flange, or prior to the 1st-stage LPC blade accumulating 7,000 CSN, whichever occurs first.
(ii) For 1st-stage LPC blades that have accumulated 6,500 or more CSN, or if the cycles since the blade was new cannot be determined, or if the cycles since the blade was last TAI inspected cannot be determined, perform a TAI inspection within 500 flight cycles or 180 days after the effective date of this AD, whichever occurs first.
(2) Thereafter, perform a TAI inspection of 1st-stage LPC blades every time the engine is separated at the M-flange and the blades have accumulated 1,000 or more flight cycles since the last TAI inspection, not to exceed 6,500 flight cycles since the last TAI inspection.
(3) If any 1st-stage LPC blade fails the inspection required by paragraph (g)(1) or (2) of this AD, remove the blade from service and replace with a part eligible for installation before further flight.
(4) The TAI inspection and disposition required for compliance with this AD must be accomplished by a method approved by the FAA. You can find a vendor that has an FAA-approved TAI inspection listed in the Vendor Services Section of Pratt & Whitney Alert Service Bulletin (ASB) PW4G-112-A72-268, Revision No. 7, dated September 6, 2018.
