EASA AD US-2020-25-09
Engine - 3rd Stage Low-pressure Turbine Duct Segments - Removal / Replacement
Summary
Federal Aviation Administration Airworthiness Directive 2020-25-09 is a final rule addressing Pratt & Whitney Division PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 model turbofan engines equipped with the Talon IIB outer combustion chamber assembly and certain 3rd stage low-pressure turbine duct segments. This directive mandates the removal and replacement of specific 3rd stage LPT duct segments due to reports of damage and failure that have caused engine surges and in-flight shutdowns. The AD aims to mitigate the unsafe condition associated with elevated gas path temperatures and component distortion.
What Changed
This new airworthiness directive introduces a mandatory requirement to remove and replace certain 3rd stage low-pressure turbine duct segments on affected Pratt & Whitney PW4000 series engines with Talon IIB combustors. It also adds Pratt & Whitney Service Bulletin PW4G-100-72-220 to the related service information. The AD does not revise compliance intervals based on flight cycles but requires replacement at every engine shop visit as defined.
Why It Matters
This AD is critical for aviation professionals because it addresses a safety risk that has led to engine surges, in-flight shutdowns, and unscheduled diversions. Operators and maintenance organizations must ensure compliance to prevent potential engine failures and maintain airworthiness. The directive also impacts maintenance planning and cost considerations due to the labor-intensive nature of duct segment replacement during engine shop visits.
What To Do
Operators of affected Pratt & Whitney PW4000 series engines must remove and replace the specified 3rd stage LPT duct segments by January 14, 2021, or at the next engine shop visit, whichever occurs first. Maintenance teams should reference the updated service bulletins, including PW4G-100-72-220, for detailed procedures. Compliance with this AD is mandatory to maintain engine airworthiness and operational safety.
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