AD 98-10-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-C47B | Airworthiness Directives; Allison Engine Company Model 250-C47B Turboshaft Engines |
Unsafe Condition
Corrosion on internal connectors of the electronic control unit (ECU) can cause annunciated hard faults, leading to uncommanded inflight engine shutdowns.
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Required Actions
Install ECUs with improved resistance to corrosion, replace the engine main electrical harness assembly with an improved assembly, install a new hydromechanical unit (HMU), remove the 'OVRSPD SYSTEM INOP' placard, and revise the Bell Helicopter Textron Model 407 Rotorcraft Flight Manual (RFM).
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Compliance Time
within 45 days after the effective date of this AD or prior to further flight if not already accomplished
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Affected Aircraft
Allison Engine Company Model 250-C47B turboshaft engines installed on but not limited to Bell Helicopter Textron Model 407 helicopters.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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