AD Amdt-39-10162
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Textron | Canada Ltd | Airworthiness Directives; Allison Engine Company Model 250-C47B Turboshaft Engines |
| aircraft | Bell | Helicopter Textron | Airworthiness Directives; Allison Engine Company Model 250-C47B Turboshaft Engines |
| engine | Allison | Engine Company Model 250-C47B | Airworthiness Directives; Allison Engine Company Model 250-C47B Turboshaft Engines |
Unsafe Condition
Failure of the overspeed protection system to reactivate the overspeed solenoid, uncommanded inflight engine shutdowns due to electrical noise in the engine control unit (ECU) and main electrical harness assembly.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Install a new hydromechanical unit (HMU) and engine control unit (ECU), replace the engine main electrical harness assembly with an improved assembly, remove the placard disabling the overspeed protection system, revise the Bell Helicopter Textron Model 407 Rotorcraft Flight Manual (RFM), and perform maintenance actions to clear ECU faults before each flight.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Before further flight
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Allison Engine Company Model 250-C47B turboshaft engines
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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