Accident Overview
An aircraft departed from Zhdanov Airport in Mariupol bound for Voroshilovgrad. Twelve minutes after takeoff, while cruising at an altitude of 4,200 meters, the crew contacted air traffic control to report stability problems and that some instruments were unserviceable. Shortly thereafter, the aircraft entered an uncontrolled descent. Thirty-eight seconds later, at an altitude of 2,750 meters, it disintegrated in mid-air and subsequently crashed in a field near Donetsk. All three crew members and the sole passenger, who was the commander of the Voroshilovgrad Higher Military Aviation School for Pilots (VVVAUSh), were killed.
Probable Cause
The official investigation determined that the accident was caused by the back-up DR-134M yaw damper power wires having been cross-wired to the wrong contacts during an overhaul at facilities in Chelyabinsk. When the damper activated during severe atmospheric turbulence, it induced yaw instead of damping it, overstressing the airframe after 38 seconds and leading to the in-flight breakup.
Aftermath
The aircraft was destroyed by impact forces and fire. No other injuries or damage on the ground were reported.