AD 84-17-51
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-C30 | ALLISON GAS TURBINE DIVISION GENERAL MOTORS CORP. Model 250-C30 and 250-C30S Engines |
| engine | Rolls-Royce Corporation | 250-C30S | ALLISON GAS TURBINE DIVISION GENERAL MOTORS CORP. Model 250-C30 and 250-C30S Engines |
Unsafe Condition
Abnormal rub of the second stage turbine nozzle interstage seal which could result in an overspeed burst of the first stage turbine wheel.
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Required Actions
Inspect the second stage turbine nozzle interstage seal for rub within 50 hours time in service after August 31, 1984, using specified bulletins or FAA-approved equivalents. Replace components with signs of abnormal rub prior to return to service, and perform repair/assembly/test procedures per listed documents.
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Compliance Time
Within the next 50 hours time in service after August 31, 1984
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Affected Aircraft
Allison Model 250-C30 and 250-C30S engines with 100 hours or less time in service since gas producer turbine rotor assembly repair or disassembly, installed in Sikorsky S76A helicopters.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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