Accident Details
After liftoff from runway 30 at Krasnoyarsk-Iemilianovo Airport, the aircraft climbed at a speed of 165 km/h before encountering difficulties gaining height. It collided with 25-meter-tall trees located approximately 1,000 meters past the runway end. The aircraft then rolled to the right and crashed in a wooded area, some 450 meters to the right of the extended centerline. Both pilots and a passenger were killed.
Investigation Findings
Investigators determined that the probable cause involved a two-fold decrease in the operating mode of the starboard engine during takeoff. This was caused by the actuation of the limiting system of the starboard engine, most likely due to the achievement of MCR limit values or a failure that issued a false signal to reduce the speed of the gas generator. The activation of the system according to the MCR should have been preceded by its connection to work, which could have occurred as a result of an out-of-order connection of the limiter unit with the automatic protection circuit breakers AZRGK TSEBO turned off, or when taking off with the AZRGK TSEBO turned on. The manifestation of a refusal in this flight was also facilitated by shortcomings in the activities of the ATB personnel of the Abakan aviation enterprise. Additionally, the crew decided to take off while the total weight of the aircraft was 280 kilograms above the maximum takeoff weight (MTOW).
Probable Cause
The official findings state: A two-fold decrease in the operating mode of the starboard engine during takeoff, caused by the actuation of the limiting system of the starboard engine and caused, most likely, with the achievement of MCR limit values, or with a failure that caused the system to be connected with the issuance of a false signal to reduce the speed of the gas generator. The activation of the system according to the MCR should have been preceded by its connection to work, which could have occurred as a result of an out-of-order connection of the limiter unit with the automatic protection circuit breakers AZRGK TSEBO turned off or when taking off with the AZRGK TSEBO turned on. The manifestation of a refusal in this flight could be facilitated by shortcomings in the activities of the ATB personnel of the Abakan aviation enterprise. Also, the decision of the crew to takeoff while the total weight of the aircraft was 280 kilos above MTOW.