What happened
During a flight departing from Zhdanely Airport (Mariupol) bound for Voroshilovgrad, the crew reported experiencing significant stability difficulties. At approximately 4,200 meters of altitude, the flight crew notified air traffic control that several instruments were non-functional and the aircraft was unstable. Shortly after this communication, the plane began an uncontrolled descent.
Approximately 38 seconds into the descent, at an altitude of 2,750 meters, the aircraft broke apart in mid-air. The wreckage eventually came to rest in a field situated near Donetsk. There were 4 fatalities in total, consisting of all three crew members and one passenger.
Findings
Investigations into the structural failure revealed that the DR-134M yaw damper was malfunctioning due to an error made during a previous overhaul at facilities in Chelyabinsk. Specifically, the backup power wires for the system had been cross-wired to incorrect contacts. When the aircraft encountered heavy atmospheric turbulence, this wiring error caused the yaw damper to induce yawing motions rather than suppressing them. This unintended movement placed extreme stress on the airframe, leading to its disintegration.