EASA AD US-2021-22-14
Engine - Low-Pressure Turbine - Replacement / Inspection
Summary
Airworthiness Directive 2021-22-14 is a final rule issued by the FAA addressing certain Pratt & Whitney PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 turbofan engines. It mandates replacement and inspection requirements for the low-pressure turbine (LPT) 4th-stage air sealing ring segment assemblies and the LPT case to prevent unsafe conditions. This directive aims to enhance engine safety by addressing issues that could lead to blade fractures and engine damage.
What Changed
This AD supersedes AD 2021-05-16 by including additional affected parts, specifically FAA-approved equivalent part numbers and PMA parts, which were previously omitted. It continues to require initial and repetitive replacements of the LPT 4th-stage air sealing ring segment assemblies and dimensional inspections of the LPT case for bulging, with repair or replacement as necessary. The update clarifies applicability and compliance requirements to better address the unsafe condition.
Why It Matters
This directive is critical for aviation professionals because it prevents potential uncontained engine failures caused by damaged LPT components, which can lead to aborted takeoffs, engine surges, and unplanned removals. Operators and maintenance organizations must comply to ensure continued airworthiness and safety of affected aircraft. The AD helps mitigate risks of engine damage and enhances operational reliability.
What To Do
Operators of affected Pratt & Whitney PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 engines must replace the LPT 4th-stage air sealing ring segment assemblies with eligible parts at the next engine shop visit or LPT overhaul, depending on engine configuration. They must also perform initial and repetitive dimensional inspections of the LPT case for bulging and repair or replace the case as needed. Compliance with these actions is required by December 17, 2021.
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