AD 84-24-54 R2
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-C30 | ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. Model 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30P | ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. Model 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30R (T703-AD-700) | ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. Model 250-C30 Series Engines |
| engine | Rolls-Royce Corporation | 250-C30S | ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORP. Model 250-C30 Series Engines |
Unsafe Condition
Cracks in turbine-to-compressor coupling P/N 23008080, carbon buildup on turbine shafts and couplings causing shaft rub, or shafting misalignment leading to disconnect failure and subsequent overspeed uncontained failure of the gas producer turbine rotor.
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Required Actions
Replace coupling P/N 23008080 with P/N 23032345 or temporary serviceable parts; inspect and clean turbine shafting/couplings, replace O-rings; modify spur adapter gearshaft and roller bearing configuration; and modify turbine-exhaust-collector as per specified CEBs. Compliance includes inspections at intervals not exceeding 300 hours time-in-service and modifications during repair/overhaul within specified deadlines.
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Compliance Time
Before further flight, within 50 hours time-in-service after effective date (January 6, 1986), or at next turbine repair/overhaul shop visit, but not later than November 30, 1986/1987 depending on engine model and installation.
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Affected Aircraft
Allison Model 250-C30, -C30P, -C30R (T703-AD-700), and -C30S engines with specified engine and turbine serial numbers installed in rotorcraft, except those incorporating listed Commercial Engine Bulletins.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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