AD Amdt-39-11263
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney | PW4000 Series | Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines |
Unsafe Condition
Potentially reduced stability in the high pressure compressor (HPC) of Pratt & Whitney PW4000 series turbofan engines, which could lead to an HPC surge event and engine power loss during critical flight phases such as takeoff or climb.
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Required Actions
Inspect and limit the number of engines with potentially reduced stability on each airplane to no more than one engine. Perform initial and repetitive on-wing or test cell cold-engine HPC stability tests. Remove engines from service if they fail on-wing test acceptance criteria. Allow follow-on test cell stability tests for engines failing on-wing tests. Establish required intervals for stability testing of the remaining engine with potentially reduced stability on the airplane. Report test data as required.
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Compliance Time
Before further flight for engines exceeding the specified criteria.
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Affected Aircraft
Pratt & Whitney PW4000 series turbofan engines installed on applicable aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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