Flight Details
On 25 April 2020, the crew of the Mil Mi-26T helicopter, registration RA-06268, was scheduled to conduct a commercial cargo flight according to plan and flight assignment No. 260308. The intended route was from Urengoy airfield to Vankor helipad and back to Urengoy. The customer was OOO "RN-Bureniye". The flight was planned to depart at 04:00.
Pre-Flight Preparations
The crew arrived at Urengoy airfield at 02:30, where the helicopter was based. Pre-flight preparation began at 02:50. The pre-flight medical examination was conducted at the Urengoy airport medical station, with entries in the medical examination log and flight assignment. The crew was cleared for the flight. At 03:15, the commander received a weather forecast from the Urengoy AMSG. The helicopter had been refueled on 20 March 2020 at Vankor helipad; no additional refueling was performed. Total fuel at takeoff from Urengoy was 9000 kg. A quality certificate for the TS-1 fuel, dated 3 February 2020, was presented. The cargo weight (equipment packed in boxes) was 13,800 kg. Takeoff weight was 52,700 kg and center of gravity was -10 mm, both within the limits specified in the Mi-26T flight manual (56,000 kg and +360 mm to -315 mm, respectively).
Departure and In-Flight Event
At 03:20, the crew boarded the helicopter. No discrepancies regarding maintenance or condition were noted, as recorded in the logbook. All required procedures were confirmed by a completed pre-flight checklist dated 25 April 2020. At 04:00, the crew, along with two service passengers, took off. The calculated flight path from Urengoy to the accident location is shown in Figure 1 of the report. At 04:40, during the flight, the crew heard a bang (хлопок).