What happened
The pilot reported that the aircraft was hovering during an external load operation when the engine suddenly lost power. At the moment of failure, blue smoke and flames were observed exiting the rear of the helicopter. The aircraft subsequently struck trees before coming to rest.
The investigation
Following the accident, investigators examined the engine to determine the cause of the failure. The engine was found to start normally during post-accident testing. It was run up to 56% N1 and 88% N2 without issue. No contaminants were found in the fuel system.
Findings
The sudden loss of power while hovering, combined with the emission of blue smoke and flames, indicates a catastrophic engine failure. The post-accident examination confirmed that the engine was mechanically sound and that the fuel system was free of contamination.
Safety message
This incident highlights the critical nature of engine performance during hover operations. Pilots must remain vigilant for signs of mechanical failure, such as unusual smoke or power loss, especially when carrying external loads which may limit maneuverability.