The engine failure was simulated by the commander reducing Engine No 1’s throttle to idle. Shortly afterwards the commander increased the throttle setting, but Engine No 1 did not respond. During attempts to resolve the problem, the throttle setting for Engine No 2 was inadvertently reduced, resulting in insufficient power being available for continued safe flight. The commander rejected the takeoff and executed a firm landing within the airfield boundary.
The subsequent engineering investigation did not find any evidence of malfunction in the engine control systems. Engine No 1 probably did not respond because the rotor rpm droop compensation had been inadvertently trimmed in the wrong direction.
This incident reinforces the benefit of using flight simulators wherever possible to de-risk training, thus avoiding the requirement for live emergency training in the helicopter. Safety action has been taken by the helicopter operator as a result of this investigation.