AD 69-18-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-C10 (T63-A-5) | ALLISON Models 250-C10 and 250-C18 Series Engines |
| engine | Rolls-Royce Corporation | 250-C10B (T63-A-5A) | ALLISON Models 250-C10 and 250-C18 Series Engines |
| engine | Rolls-Royce Corporation | 250-C10D (T63-A-700) | ALLISON Models 250-C10 and 250-C18 Series Engines |
| engine | Rolls-Royce Corporation | 250-C18 | ALLISON Models 250-C10 and 250-C18 Series Engines |
| engine | Rolls-Royce Corporation | 250-C18A | ALLISON Models 250-C10 and 250-C18 Series Engines |
| engine | Rolls-Royce Corporation | 250-C18B | ALLISON Models 250-C10 and 250-C18 Series Engines |
| engine | Rolls-Royce Corporation | 250-C18C | ALLISON Models 250-C10 and 250-C18 Series Engines |
Unsafe Condition
Excessive wear of the internal splines on the P/N 6840847 helical power train drive gear.
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Required Actions
Inspect the internal spline using Allison P/N EX 83339 plug gage. Replace the gear with a new or serviceable part if the gage enters the spline. Modify the engine per Allison CEB-61 to eliminate future inspections.
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Compliance Time
Within the next 50 hours' time in service after the effective date, for engines with 750+ hours since new/overhaul, or at or before 800 hours' time in service for those with less than 750 hours at effective date.
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Affected Aircraft
Rolls-Royce Corporation Models 250-C10 (T63-A-5, T63-A-5A, T63-A-700) and 250-C18 (C18, C18A, C18B, C18C) series engines.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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