Airworthiness Directive · Amendment 39-23451 · Turbine engine compressor section
Pratt & Whitney Division Engines
This AD applies to all Pratt & Whitney Division (PW) Model PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 engines.
The FAA is adopting a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) Model PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 engines. This AD was prompted by the discovery of a quality escape involving incorrect shot peening on certain high- pressure compressor (HPC) drum rotor disk assemblies. This AD requires visually inspecting the HPC drum rotor disk assembly for incorrect shot peen coverage and, depending on the results of the inspection, replacing the HPC drum rotor disk assembly with a part eligible for installation. This AD also requires removing and replacing certain HPC drum rotor disk assemblies before reaching certain life limits. The FAA is issuing this AD to address the unsafe condition on these products.
For the purpose of this AD, a “part eligible for installation” is:
(1) Any HPC drum rotor disk assembly having a part number (P/N) and serial number (S/N) that is not identified in paragraph (h) of this AD.
(2) Any HPC drum rotor disk assembly having a P/N and S/N identified in paragraph (h)(1) of this AD that has passed the inspection required by paragraph (h)(1) of this AD.
(1) For HPC drum rotor disk assemblies having P/N 50S634, and S/N CENCD26931, CENCD29577, CENCD29597, CENCD41851, or CENCD43536, as applicable, before accumulating the total life cycles since new in Table 1 of the Accomplishment Instructions of PW Alert Service Bulletin (ASB) PW4G-112-A72-373, dated September 10, 2025 (PW ASB PW4G-112-A72-373), perform a visual inspection of the HPC drum rotor disk assembly in accordance with the Accomplishment Instructions, paragraph 1.B., of PW ASB PW4G-112-A72-373.
(2) If, during the inspection required by paragraph (h)(1) of this AD, evidence of incorrect shot peening is discovered, before further flight, replace the HPC drum rotor disk assembly with a part eligible for installation.
(3) For the HPC drum rotor disk assembly having P/N 50S634 and S/N CENCD30975, before accumulating 9,800 total life cycles since new, remove the HPC drum rotor disk assembly from service and replace with a part eligible for installation.
(4) For the HPC drum rotor disk assembly having P/N 50S634 and S/N CENCD42978, before accumulating 11,000 total life cycles since new, remove the HPC drum rotor disk assembly from service and replace with a part eligible for installation.
