What happened
On the evening of the accident, an aircraft departed from Yeniseysk Airport at 16:55 local time, heading toward Krasnoyarsk. While cruising at an altitude of approximately 1,800 meters under clear weather conditions and nighttime visibility, the crew identified a mechanical issue involving the left propeller, which had begun overspeeding.
Efforts to feather the propeller were unsuccessful, prompting the crew to initiate an emergency return to Yeniseysk. The increased drag from the malfunctioning engine caused the aircraft to lose altitude. While flying at a speed of 130 km/h, the plane struck treetops and crashed in a forested region situated 25 km south of the departure airport. The impact resulted in three fatalities and left 16 others injured. The aircraft was completely destroyed during the event.
Findings
Investigations determined that the primary cause of the propeller overspeed was the failure of a pressure switch located on the left-hand drive regulator. This mechanical malfunction prevented the crew from properly managing the engine's rotation.
A significant contributing factor involved the crew's management of the right engine during the descent; they failed to set the correct operational mode immediately, instead maintaining full power on the right engine with a delay, which accelerated the loss of altitude. Additionally, despite having sufficient visibility provided by moonlight, the crew did not attempt an emergency belly landing in more suitable terrain.