Pilot Debrief

BELL 407 near Columbia, MD — 2013-05-31

Final reportERA13TA261
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Date
2013-05-31
Location
Columbia, MD, USA
Aircraft
BELL 407
Registration
N407HC
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Climb

Probable cause

The short circuit failure of a tantalum capacitor, internal to the engine’s electronic control unit, resulting in an uncommanded shutdown of the engine in flight.

NTSB narrative

During a routine police patrol flight, while about 600 feet above the ground, the helicopter suddenly yawed to the left and the red "ENGINE OUT" warning light illuminated. The engine lost all power and the pilot performed an autorotation landing on a nearby football field. While avoiding obstacles, the helicopter landed hard, resulting in substantial damage to the airframe. A postaccident examination of the engine revealed no damage or obvious reason for the loss of power. The engine's electronic control unit (ECU) was removed and was shipped to the manufacturer's facility for evaluation and testing. The examination of the ECU revealed that the engine was operating normally until an unexpected activation of the full authority digital electronic control overspeed protection system fuel reduction solenoid, which is internal to the ECU, resulting in an uncommanded in-flight engine shutdown. A subsequent ECU functional review confirmed that a short circuit failure of a tantalum capacitor was the source of the ECU malfunction. After the accident, Bell Helicopter issued an Alert Service Bulletin and Rolls-Royce issued an accompanying Commercial Engine Bulletin that included the installation of an overspeed adapter to reduce the likelihood of a false overspeed activation.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Compliance with Rolls-Royce CEB 73-6052 could have prevented ECU malfunction.

NTSB coding

Evidence available

  • Photos
  • 9 docket documents
View NTSB final reportView NTSB docket

Docket documents9

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