Airworthiness Directive · Amendment 39-22552 · Turbine engine compressor section
Pratt & Whitney Division Engines
This AD applies to all Pratt & Whitney Division Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines.
The FAA is superseding Airworthiness Directive (AD) 2018-21- 11, which applied to all Pratt & Whitney Division (PW) Model PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 engines with a low-pressure compressor (LPC) fan hub, part number (P/N) 51B821 or P/N 52B521, installed. AD 2018-21-11 required performing repetitive eddy current inspections (ECIs) and fluorescent penetrant inspections (FPIs) for cracks in certain LPC fan hubs and removing LPC fan hubs from service that fail any inspection. Since the FAA issued AD 2018-21-11, the FAA determined that affected LPC fan hub assemblies can meet the published certificated life limit without the need for the required repetitive FPI inspections in AD 2018-21-11, and the repetitive ECI inspections require shortened intervals. Based on a report of another incident, the FAA determined that the unsafe condition is likely to exist or develop on additional LPC fan hub assemblies and PW model engines. This AD expands the applicability to include Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines with any part number LPC fan hub assembly installed and requires performing repetitive ECIs of the LPC fan hub assembly and, depending on the results of the inspections, removing the LPC fan hub assembly from service. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Before accumulating 550 flight cycles (FC) after the effective date of this AD, and thereafter at intervals not to exceed 550 FC since the last eddy current inspection (ECI), perform an ECI of the LPC fan hub assembly, in accordance with the Accomplishment Instructions, For Engines Installed on Aircraft, paragraph 2., or For Engines Not Installed on Aircraft, paragraph 3; of Pratt & Whitney Alert Service Bulletin (ASB) PW4G-112-A72-362, Revision No. 2, dated August 2, 2023 (ASB PW4G-112-A72-362, Revision 2).
(2) If a rejectable indication is found during the inspections required by paragraph (g)(1) of this AD, before further flight, replace the LPC fan hub assembly with a part eligible for installation.
After the effective date of this AD, do not install an LPC fan hub assembly on any engine, unless it is a part eligible for installation as defined in paragraph (k) of this AD.
This AD does not require reporting certain information to the manufacturer as specified in ASB PW4G-112-A72-362, Revision 2.
