AD 77-09-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-B17 | DETROIT DIESEL ALLISON Model 250-C20, C20B, C20C, B17, B17B Engines |
| engine | Rolls-Royce Corporation | 250-B17B | DETROIT DIESEL ALLISON Model 250-C20, C20B, C20C, B17, B17B Engines |
| engine | Rolls-Royce Corporation | 250-C20 | DETROIT DIESEL ALLISON Model 250-C20, C20B, C20C, B17, B17B Engines |
| engine | Rolls-Royce Corporation | 250-C20B | DETROIT DIESEL ALLISON Model 250-C20, C20B, C20C, B17, B17B Engines |
| engine | Rolls-Royce Corporation | 250-C20C (T63-A-720) | DETROIT DIESEL ALLISON Model 250-C20, C20B, C20C, B17, B17B Engines |
Unsafe Condition
Bleed valve diaphragm failure could cause engine power loss.
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Required Actions
Clip lockwire and remove exit nozzle P/N 6874818 from the bleed valve cover. Install strainer assembly P/N 6896347 in the valve cover exit port until fully seated. Reinstall exit nozzle and tighten to 35-45 lb. in. Remove exit nozzle and strainer assembly to clear passages of burrs, motor engine over 10% rpm, then reinstall strainer and nozzle as specified. Secure with lockwire.
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Compliance Time
within the next 30 calendar days after the effective date of this AD, unless already accomplished
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Affected Aircraft
Rolls-Royce Corporation 250-B17, 250-B17B, 250-C20, 250-C20B, 250-C20C (T63-A-720) engines
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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