AD 2001-04-16
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | General Electric | Company CF6-50 Series | Airworthiness Directives; General Electric Company CF6-50 Series Turbofan Engines |
Unsafe Condition
Cracked, loose, or missing stage 2 low pressure turbine (LPT) nozzle lock assembly studs could lead to failure of the locks, nozzle segment rotation, LPT case machining, and subsequent uncontained failure of the engine.
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Required Actions
Install the solid borescope plug for engines not yet compliant. Perform on-wing or off-wing initial and repetitive ultrasonic inspections of stage 2 Waspalloy LPT nozzle lock assembly studs for cracks. Perform on-wing or off-wing initial and repetitive visual inspections of stage 2 LPT nozzle lock assembly studs for loose or missing studs. Replace all stage 2 LPT lock assemblies with new design assemblies before further flight if a cracked, loose, or missing stud is found. Incorporate additional stage 2 LPT nozzle locks as an interim action if no indications of nozzle rotation are found, within 3,500 cycles-in-service. Inspect the area surrounding the borescope plug for buckling or cracks whenever nozzle lock studs are inspected. Inspect for loose or missing added nozzle locks and LPT case cracking in the areas of the added nozzle locks every 750 hours time-in-service. Replace the LPT lock assemblies with new design assemblies before further flight if any LPT case buckling or cracks are found, or if nozzle segment rotation is found.
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Compliance Time
Before further flight for critical actions; within 3,500 cycles-in-service for interim actions.
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Affected Aircraft
General Electric Company CF6-50 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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