What happened
During a test flight departing from Valikhanovo, an aircraft experienced a catastrophic mechanical failure. The flight was being conducted following engine repairs performed as part of recent crop-spraying operations in the Valikhanovo district. While airborne, a propeller blade detached due to a fatigue fracture. This separation triggered intense vibrations throughout the airframe, which subsequently caused the engine mount to fail.
As the aircraft lost structural stability, it veered to the left. The rotating propeller struck the spar of the left lower wing, resulting in the collapse of the wing box. Following this structural failure, the aircraft became uncontrollable and impacted a field located approximately 2 km south-southwest of the Yuzhny collective farm (coordinates N52°33' E71°36'). The accident resulted in three fatalities, including both pilots and one passenger, who was an aircraft mechanic. Notably, the propeller assembly had been installed just one day prior to the incident.
Findings
Investigations determined that the primary factor in the accident was the separation of a propeller blade during flight.