What happened
During a nighttime approach to Bugulma Airport, the aircraft experienced a sudden mechanical failure when the left propeller entered autofeather mode. This event caused a significant reduction in airspeed and induced a leftward veer. While the crew attempted to stabilize the flight path and maintain directional control, the aircraft's velocity continued to decline.
As the speed reached 140 km/h, the aircraft entered a steep left bank of 110 degrees before stalling. The subsequent impact occurred in a field situated approximately 8 km from the runway threshold and 500 meters away from the extended centerline. The accident resulted in 38 fatalities and the total destruction of the aircraft.
Findings
Investigations revealed that the left propeller autofeathered just one second after the deployment of 38° flaps. This malfunction was triggered by the failure of an electrical switch linked to the automatic feathering system. The resulting loss of stability and controllability, compounded by several errors made by the crew, prevented them from correcting the abnormal yaw and roll.