What happened
On January 20, 2015, the pilot of an R-66 helicopter received instructions from the head of LLC Kustard to transport 20 passengers to the Kosh-Agach district of the Altai Republic for a wolf hunting expedition. The flight plan, filed through West Siberian Air Navigation, involved a route from Kuzedeevo to Kosh-Agach, followed by coordinates along the Mongolian border. The crew had obtained the necessary flight permits and coordination with the border service for operating in the border zone. The mission was planned as a visual flight rules (VFR) operation within Class G airspace, with the pilot obtaining meteorological information via the internet.
At 02:10, the pilot performed a pre-flight inspection of the aircraft. At 02:45, the helicopter departed Kuzedeevo with two passengers on board. The aircraft landed at 04:10 at an unprepared landing site on the outskirts of Kosh-Agach. The initial leg of the flight proceeded normally. Upon arrival, the remaining fuel was 40 liters. The pilot then refueled the aircraft with 160 liters of TS-1 fuel provided by an Avialesozahrona fuel truck. This brought the total fuel load to 200 liters, out of a maximum capacity of 280 liters. To prevent water crystallization, IM additive was added to the fuel according to temperature recommendations.
At the time of the return departure from Kosh-Agach, the takeoff mass was 1071kg, which was within the R-66 maximum takeoff weight limit of 1225kg. The center of gravity was 2390mm, within the permitted range of 2310–2540mm. At 05:20, the pilot departed Kosh-Agach with three passengers on board for a mission in the interests of the operator.