Aeroflot flight 7841

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Aeroflot flight 7841
Tupolev Tu-134, Aeroflot JP10318.jpg

An Aeroflot Tu-134
Accident summary
Accident type Emergency landing in the field after failure of both engines
place 10 km east of the Minsk-2 airport near Nezhevka , Belarusian SSRBelarus Soviet Socialist RepublicBelarusian SSR 
date February 1, 1985
Fatalities 58
Survivors 22nd
Aircraft
Aircraft type Tupolev Tu-134 AK, Soviet UnionSoviet Union 1955Soviet Union 
operator Aeroflot , Soviet UnionSoviet Union 1955Soviet Union 
Mark CCCP-65910, Russian SFSRRussia Soviet Federal Socialist RepublicRussian SFSR 
Departure airport Minsk-2 Airport, Belarusian SSRBelarus Soviet Socialist RepublicBelarusian SSR 
Destination airport Leningrad Pulkovo Airport , Russian SFSRRussia Soviet Federal Socialist RepublicRussian SFSR 
Passengers 74
crew 6th
Lists of aviation accidents

On February 1, 1985, a Tupolev Tu-134 had to make an emergency landing on the inner-Soviet scheduled flight Aeroflot flight 7841 from Minsk to Leningrad (today: Saint Petersburg ) after the failure of both engines, with 58 of the 80 passengers dying. After Aeroflot flight 8641, it is the second most serious aircraft accident in what is now Belarus .

Plane and crew

The aircraft was a twin-engine Tupolev Tu-134 A (aircraft registration number CCCP-65190, serial number 63969), which had completed 685 flight hours and 448 flight cycles from May 11, 1982 until the accident.

The crew consisted of the flight captain Vladimir Dmitriyevich Baljajew, the first officer Mikhail Ivanovich Chaustow, the flight engineer Anatoly Vladimirovich Trofimenko, the navigator Vyacheslav Andreevich Dubinin, the flight attendant Alexander Arkadyevich Gulutaarja and the flight attendant.

Weather

The following weather conditions prevailed before take-off: fog, dense clouds with a cloud base of 160 m. The air temperature was −2 ° C and the humidity was 94%. In addition, there was a wind from the south (180 °) with 5 m / s (18 km / h) and gusts of up to 8 m / s (approx. 29 km / h) and additionally a wind from the southwest (240 °) at 12 m / s (approx. 43 km / h)

course

At 7:47 PM, the aircraft was on its parking position on the runway towed, where at 7:52 PM both engines were started with 40 second intervals and then choose the Flugzeugenteisungssystem activation. The engines ran to 77% thrust for 1 minute to warm up . The 46 t Tu-134 took off at 7:59:35 a.m. on course 134 ° (southeast) after, as calculated, a 1,300 m take-off distance at a speed of 290 km / h. At 7:59:41 a.m., 6 seconds after take-off, the speed of the left engine dropped to 35 m and a speed of 325 km / h, followed by a bang and a drop in temperature behind the turbine. The ensuing roll and yaw movement compensated for the crew and the aircraft continued to climb. The first officer Chaustow informed the air traffic controller about the engine failure and the intention to land on the opposite course. Thereupon the radio navigation and the runway lighting for a landing on course 314 ° (northwest) were switched within 1.5 seconds . Flight engineer Trofimenko began to retract the landing flaps at an altitude of 220 m and a speed of 340 km / h at the instruction of Captain Baljajew , when at the end of this process at 8:00:40 a.m., 2 alarm lights warned of the failure of the right engine and excessive vibrations. At 8:00:42 the speed of the right engine also fell, while the Tu-134 was flying through clouds at a height of 240 m at a speed of 325 km / h.

In order to keep the speed in gliding flight, Captain Baljajew initiated a descent at 7 m / s and broke through the cloud cover at a height of 100-120 m. Since a further flight was no longer possible, the pilots decided to land in the forest in front of them, the trees of which were up to 30 m high. On the 22 m by 5 ° to the right stripped inclined plane, the first top and began to break down until it at 8:01 PM 354 m after the first tree contact with a right angle of 15-22 ° hit the ground at the following collisions. The plane skidded another 110 m and broke into 2 parts. The front part rotated 90 ° to the right, the rear part 35 ° to the side.

The wreck, which was completely burned out except for the tail unit, was not found until 11:15 a.m. with a significant delay. A total of 55 passengers died, as well as flight engineer Trofimenko, navigator Dubinin and flight attendant Bondarenko.

Investigations by investigators

The investigation indicated that both engines failed after the ice that was sucked in damaged the 1st compressor disk, which destroyed the blades of the compressor disks behind and burned the turbine blades. In the de-icing system, a hole (diameter: 1 mm) was found in the seal of a pipe that was supposed to direct hot air to the engine inlet. However, no evidence was found that this affected the de-icing system.

The Tu-134 was parked on an uncovered parking lot between January 25 and February 1, exposing it to outside temperatures and precipitation. Maintenance work was carried out on January 30th and 31st. On the day of the accident, both wings were de-iced with hot water and a de-icing fluid immediately before take-off. Since there was no evidence of ice or snow on the hull, they were not treated. The weather records showed that the weather conditions did not allow icing on the ground shortly before the start. The state aviation research institute GosNII GA used peas instead of ice for tests and came to the conclusion that it is impossible for enough ice to form on the aircraft's outer skin for an engine failure .

The investigators came to the conclusion that both engines failed after the compressor pumps were caused by sucked in ice, the compressor disks were destroyed and the turbine blades burned. Due to the degree of destruction to the aircraft and engines, they could not understand what exactly led to it. Contrary to this, commissioners representing the Ministry of Aviation and the Design Bureau insisted that the inadequate de-icing and its control led to the ice that formed on the ground during the idle period remaining on the wings.

Study of the GosNII GA

The State Research Institute for Civil Aviation (GosNII GA) published a study in January 1988, almost 3 years after the accident, which looked at ice formation on the ground. Due to outside temperatures of down to −20 ° C (measured on January 28th and 29th), the fuel in the full tanks cooled to below 0 ° C. On the day of the accident, the fuel temperature was between −5 and −2 ° C. Treatment with hot water and de-icing fluid resulted in the formation of up to 200 kg of clear ice .

The take-off at take-off increased the angle of attack on the wings and created a vacuum on the upper sides of the wings, which is why ice peeled off on the left wing and the left engine failed. Due to the cross wind and the temperature difference between the surfaces of both wings, the ice on the right wing was more stuck. This only came loose when the airplane was shaken by the retraction of the landing flaps, whereupon the right engine failed.

Similar cases

Scandinavian Airlines flight 751 on December 27, 1991: In the similarly built McDonnell Douglas MD-81 , both engines failed due to clear ice for a similar cause, whereupon the pilots made an emergency landing.

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