AD Amdt-39-10091
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | AlliedSignal | Inc. ALF502 and LF507 Series Turbofan | Airworthiness Directives; AlliedSignal Inc. ALF502 and LF507 Series Turbofan Engines |
Unsafe Condition
No. 4 and 5 duplex bearing failure, which can result in a Stage 4 low pressure turbine (LPT) rotor failure, an uncontained engine failure, and damage to the aircraft.
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Required Actions
Conduct initial inspection of oil system chip detectors and oil filter bypass valve, perform repetitive inspections, and optionally install an improved oil filter bypass valve to ensure reduction gear system and overspeed protection system integrity.
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Compliance Time
Before further flight
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Affected Aircraft
AlliedSignal Inc. ALF502 and LF507 series turbofan engines
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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