During a test flight with departure and destination at Khabarovsk, a fuel line broke and 8 tons of fuel leaked inside the right wing. Due to the frequent failures in the measure of fuel, the abnormal quantity of the remaining fuel was not taken in count.
At 18:45 h a fire alarm began on engine 3 and the crew shut it down. An emergency situation was declared and the aircraft turn 180 degrees to return to Khabarovsk. The engine 4 was also disconnected to prevent the fire propagation and the commander has reported to the ground that goes on two engines.
The cabin filled quickly with black smoke and the possibility of reaching the airport disappeared when a
third engine failed, then the commander decided an emergency landing without the landing gear on a field
During the landing the nose cone collapsed and introduced into the cabin, killing two members of the crew. The rest of the crew abandoned the aircraft with different injuries and the plane was consumed by fire. All events have take place within 6 minutes.
The official conclusion of the Governmental Commission estimated that the fuel leak was caused by the fatigue of a fuel pipeline, probably the pipe of an experimental APU (auxiliary power unit). The leak began at 18:18 h with a charge of 220 kg per minute and reached 8,000 kg at the end of the flight. The commission excluded any responsibility of the crew in the accident and emphasized like heroic their attempts for to rescue the comrades.