On November 1, 2016, a Eurocopter AS-350 B3e, registration RA-07275, operated by Yeltsovka Aviation Enterprise, was conducting a planned familiarization flight over the Black Sea coast. The flight, which included five passengers, departed from a takeoff site in the village of Kazachiy Brod, Sochi, under Instrument Flight Procedures (IFR) within controlled airspace.
The flight proceeded without incident until the aircraft approached the coastline. While attempting a right turn toward Olympic Park, the helicopter experienced a rapid increase in right roll accompanied by an increased vertical rate of descent. The aircraft RA-07275 entered a maneuver involving bank angles of up to 60 degrees and an airspeed of approximately 150 knots, with vertical G-forces reaching 2.1 g.
This maneuver led to the occurrence of 'servo transparency,' a phenomenon that the pilot-in-command was unable to recover from. The helicopter subsequently collided with the ground in the area of Tsimlyanskaya Street, Adler city, and was destroyed.
The accident resulted in two fatalities and left the pilot and three passengers with serious injuries.