The Tupolev 144 supersonic passenger jet was to make a test flight before delivery to Aeroflot. At an altitude of 3000 m a fire started at the APU, located in the right delta-shaped wing. A turn was made to return to the airport and the both engines located in the right wing (engines no. 3 and 4) were shut down. The plane began to lose height. Fire trailed the plane and the cockpit filled with smoke. Then one of the remaining two engines failed. The crew managed to belly land the plane in a field, six minutes from the moment of the beginning of the fire. On impact the nose cone collapsed under the fuselage, penetrating the compartment in which two flight engineers were seated. It appeared that 27 minutes prior to the ignition, a fuel line ruptured, causing eight tons of fuel to leak, entering several compartments of the right wing. The fuel readings were judged incorrect by the flight engineers and where thus not reported to the commander.