Airworthiness Directive · Amendment 39-18815 · Pratt & Whitney Division Turbofan Engines
Pratt & Whitney Division Turbofan Engines
This AD applies to all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines.
We are adopting a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines. This AD was prompted by an uncontained failure of a high-pressure turbine (HPT) hub during takeoff. This AD requires an inspection to measure the surface condition of the aft side web/rim fillet of HPT 1st stage hubs and removal from service of hubs that fail inspection. We are issuing this AD to correct the unsafe condition on these products.
(1) After the effective date of this AD, perform the HPT 1st stage hub web/rim fillet replication inspection and measurement as follows:
(i) For PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 engine models, the next time the engine is disassembled sufficiently to expose the HPT module, use the Accomplishment Instructions, Part A, paragraphs 2.A. and 2.B.(1) through 2.B.(4) of PW Service Bulletin (SB) PW4G-112-72-342, dated September 23, 2016, to do the inspection.
(ii) For PW4074 and PW4077 engine models, the next time the HPT module is disassembled sufficiently to expose the HPT 1st stage hub, use the Accomplishment Instructions Part B, paragraphs 1.A. and 1.B.(1) through 1.B.(4) of PW SB PW4G-112-72-342, dated September 23, 2016, to do the inspection.
(2) If the hub fails the inspection, remove the hub from service before further flight and replace with a part eligible for installation.
After the effective date of this AD, do not install, or re-install into any engine, any HPT 1st stage hub that has not been inspected and passed the inspection required by paragraph (e) of this AD.
