What happened
During a local training mission departing from Västerås Airport, the aircraft experienced a failure of the left engine which subsequently ignited. While attempting to maintain a stable altitude following the malfunction, the pilot encountered difficulty feathering the propeller. This inability to adjust the propeller pitch resulted in a significant loss of airspeed and altitude.
As the aircraft descended, it passed over high-voltage power lines carrying approximately 70,000 volts before impacting a forested area. The impact was followed by an intense fire. The accident resulted in six fatalities and five serious injuries. One of the survivors succumbed to their wounds three days after the event.
Findings
Investigations into the accident determined that the primary mechanical failure was a breakage in the left engine's crankshaft during the initial climb phase. Furthermore, the crew was unable to feather the propeller for reasons that remain unconfirmed. This caused the engine to windmill, creating excessive aerodynamic drag that prevented the aircraft from maintaining flight and led to the eventual loss of control.