Airworthiness Directives; Pratt & Whitney Division Engines
Key claim: Operators of certain Pratt & Whitney PW4000-series engines must inspect high-pressure compressor drum rotor disks for incorrect shot peening and replace affected parts, including some before they reach their usual life limits.
Abstract
(Rule · Transportation Department, Federal Aviation Administration) 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.
Why this matters
Shot peening is a fatigue-life-critical manufacturing step for rotating engine parts, so a quality escape on high-pressure compressor drum rotor disks can shorten safe service life below published limits and risk uncontained failures. This AD forces early inspection and replacement on specific PW4000-series engines, adding to a recent pattern of PW4000 rotor and sensor ADs prompted by discrete failure or manufacturing events.