The Yak-40 plane crashed in the evening in Tashkent. Earlier it was reported that the An-24 plane crashed.
37 people died in the plane crash - 32 passengers and 5 crew members. This is stated in a government message released in Tashkent late on Tuesday evening. Previously, information was received about 36 deaths.
The plane belonged to the Uzbekistan Airways company (Uzbekistan Airways).
According to this message, at 19:27 local time, a Yak-40 plane flying on a Termez-Tashkent flight crashed during landing near Tashkent airport.
“It fell on the runway and exploded,” Tashkent airport told Reuters.
The plane was operating flight 1154 Termez-Tashkent.
“Black boxes” were found at the crash site of the Yak-40 plane at Tashkent airport.
The Yak-40 plane crashed onto the runway in close proximity to residential areas of the city. The crash site is separated from nearby houses by no more than 100 meters. There are no reports of casualties among the population. The area where the plane crashed has been cordoned off by police.
According to forensic experts, the bodies of all the victims were badly burned.
In particular, it became known that during landing, instead of the long-range drive, the crew landed on the short-range drive. Moreover, at an altitude of 60 m, the pilots turned on the reverse - the braking system, which should be activated only when the aircraft’s wheels touch the runway, since when the reverse is turned on, the flaps in the nozzles close.
When the crew realized their mistake, they tried to gain altitude, but they no longer had the required 30 seconds that are needed after the reverse is removed. The plane passed almost the entire runway at an altitude of 60 meters, thinking that this was the beginning of the runway.
The plane, having flown the entire length of the runway, crashed into a concrete fence at a height of 2 m. For reasons that have not yet been established, the Yak-40 chassis never touched the ground. Having broken through the fence, the plane caught fire and crashed into the Kara-Su canal.
According to Reuters, parts of the victims are scattered over a large area near the Tashkent airport. The agency's correspondent witnessed how, a few hours after the disaster, rescuers collected parts of the bodies of the victims into large bags.
There is heavy fog in the airport area, but airport officials say visibility was sufficient for the plane to land.
As the Prosecutor General of Uzbekistan Rashitjon Kadyrov said, the crashed Yak-40, when landing at an altitude of two meters, lost its landing gear, it hit the concrete fence of the runway and exploded. Previously, fog was considered the main cause of the disaster.
The General Prosecutor's Office of the Republic opened a criminal case on the fact of the plane crash under Article 260, part 3, paragraphs “a” and “b”, of the Criminal Code of the Republic - “violation of traffic safety rules and operation of railway, sea, river or air transport, resulting in human casualties.” victims,” Kadyrov said.
Speaking about the technical condition of the aircraft, Rashitjon Kadyrov said that the aircraft was produced in 1975, its service life was 38 thousand hours, and at the time of the disaster 37 thousand had been worked. The last time the plane was repaired was in 1999 in Minsk. At the same time, more than a thousand hours of engine life remained, the Prosecutor General noted.
According to him, the plane was flown by an experienced crew. The crew commander, Alexander Aleksanov, born in 1960, a native of the Kemerovo region, had flight experience since September 16, 1977, Kadyrov said.
More than a hundred people have already been questioned in the case. Personal belongings of passengers were confiscated from the scene of the incident and appropriate examinations are being carried out. The aircraft wreckage will be evacuated to an aircraft hangar, where it will be further examined.
A government commission has been created to investigate the circumstances and causes of the disaster, which has already begun work.
The leadership of Uzbekistan expressed condolences to the families and friends of the victims.
The representative of the State Civil Aviation Service (SCAS) Vladimir Masenkov said that Uzbekistan Airlines “is one of the strongest airlines in the CIS after the collapse of the USSR.”
“It’s very unfortunate that such a disaster occurred in this airline,” Masenkov said.
According to an employee of the representative office, the IAC will deal with the circumstances of the Yak-40 crash in Tashkent. The IAC includes specialists from all CIS countries. The Baltic countries are represented on the committee by observers.
The crew and passengers of the Yak-40 plane - 37 people - were burned alive in a plane crash on the tarmac of Tashkent airport.
The half-filled fuel tanks exploded, leaving no chance for passengers and crew to survive.
According to preliminary data, there were no Russian citizens on board the Uzbek Airlines Yak-40 plane that crashed near Tashkent. Konstantin Mineev, head of the consular department of the Russian Embassy in Uzbekistan, told RIA Novosti about this by phone.
The head of the UN Office in Uzbekistan, Richard Conroy, was on board the Yak-40 aircraft. RIA Novosti was informed about this by the press service of the UN headquarters in New York.
Among those killed in the plane crash near Tashkent was a representative of an American humanitarian organization, US citizen Richard Penner. The Prosecutor General of Uzbekistan, Rashitjon Kadyrov, told reporters about this on Wednesday. Among the dead were also two Afghan citizens.
The Prosecutor General of Uzbekistan clarified that 37 people died as a result of the disaster:
32 men, four women and one child (5 dead - aircraft crew).
Today we can name several possible causes of the accident. In addition to the technical malfunction that Prosecutor General Kadyrov spoke about, bad weather could have led to the disaster: at the time of landing at Tashkent airport there was such thick fog that dispatchers advised pilots of all flights to land in Samarkand.
Note that the words of eyewitnesses refute both of these assumptions: they claim that the plane caught fire in the air, and not after hitting the fence. In this case, there was obviously some kind of explosion on board the Yak-40, which means there could have been a terrorist attack. None of these versions can be ruled out yet.
Resolution of the Cabinet of Ministers of the Republic of Uzbekistan
On January 13, 2004, at the Tashkent airport there was a plane crash of a Yak-40 aircraft of the NAC Uzbekistan Airways, operating flight No. NU-1154 on the Termez-Tashkent route. 37 people were killed, including 5 crew members.
In connection with the tragic events that led to the disaster and loss of life, the Cabinet of Ministers decides:
1. Create a government commission to investigate the causes of the plane crash.
Grant the Commission the right to involve in the investigation of the causes of the plane crash and the liquidation of its consequences specialists and experts from relevant ministries and departments who can assist in the qualified implementation of these works.
2. Government commission:
— organize work to excavate and examine the wreckage of the aircraft, extract and conduct a forensic medical examination of the bodies of the dead, as well as establish their identities;
— ensure the delivery of the bodies of the deceased to their relatives at their place of residence, provide assistance and take part in organizing and conducting funerals;
— conduct an in-depth investigation of the circumstances leading to the accident. The Prosecutor General's Office should initiate a criminal case in accordance with the law into the plane crash and ensure that the necessary operational and investigative measures are carried out;
— to provide, in the prescribed manner, material and other assistance to the families of citizens who died as a result of the plane crash;
— report on the results of the work done and proposals to eliminate such incidents in the future by January 25, 2004.
3. Declare January 15, 2004 throughout the country a day of mourning for the citizens killed in the plane crash.
Chairman of the Cabinet of Ministers
Islam KARIMOV.
Also read the decision of the commission investigating the plane crash.
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Information: NEWSru.com, Magnolia TV, Avia.ru, Uzreport.com
The photo shows a Yak-40 from another airline.
Yak-40 plane crash near Makhachkala - a crash that occurred on November 7, 1991 with a Yak-40 aircraft of Yugavia Airlines en route from Elista to Makhachkala. During landing, the plane crashed into a mountain. 51 people died.
Events
On November 7, 1991, a Yak-40 aircraft flew C-519 Elista - Makhachkala. The crew consisted of 4 people: commander, co-pilot, flight mechanic and flight attendant. At Elista airport, 34 passengers were boarded on a 32-seat plane, and then another 13 stowaways were added. As a result, at 12.43 p.m., a plane took off from Elista airport with an overload of 260 kilograms, although the alignment of the plane was within acceptable standards.
The flight was supposed to pass through the points Aktur, Almar, Ronka and Kizlyar, and then enter the descent area for landing. The crew contacted the dispatcher and requested permission to fly off-route and head straight to Kizlyar, bypassing Ronchi. Probably, not wanting to complicate his work, the dispatcher of the North Caucasus Center forbade the flight to Kizlyar, but allowed off-route flight. Later, the dispatcher informed the crew about their location and gave instructions to proceed to Kizlyar, which was done.
The airliner entered the sector, so the crew contacted the dispatcher of the Astrakhan center and reported to him about the flight at a flight level of 5700 meters and about the estimated time to pass Kizlyar. In response, the dispatcher, violating the flight instructions of the Makhachkala airport, gave the command to follow off the route directly to the Makhachkala drive. The crew knew that in this case they would have to fly over the Kanaburu mountain range, but nevertheless carried out the command, turning after flying over Kizlyar to the Makhachkala drive.
The Yak-40 descended to a flight level of 5100 meters and, 100 kilometers from the Makhachkala airport and 35 kilometers to the right of the air corridor, communicated with the approach controller and lied to him about entering the airport area along the air corridor. The approach controller, although he saw on the long-range radar screen that the plane was actually at an unspecified point, did not take it to the established route and did not even indicate to the pilots their location. Instead, in violation of the instructions, he gave the command to descend to an altitude of 1800 meters, although the plane in this case was descending into a dangerous sector for flights towards a mountain range that had heights of 890 and 720 meters. Then, when the airliner was at an altitude of 1800 meters, 45 kilometers from the Makhachkala airfield and 23 kilometers to the right of the route, the approach controller gave instructions to communicate with the landing controller. The crew confirmed the instructions, without specifying their location or entering the designated route.
41 kilometers from the airport, the crew contacted the landing controller, who gave the crew the wrong location. The dispatcher also gave permission to descend to an altitude of 1050 meters and head towards the drive, although the instructions established a minimum altitude of 1800 meters. But the crew blindly began to follow the instructions and soon found themselves in a zone of “darkening” by mountain peaks, as a result of which the illumination of the flight on the radar screen periodically disappeared. Not seeing the light on the screen, the dispatcher named the estimated location of the plane. Two incorrect messages in a row about the location of the aircraft misinformed the crew and created in them the erroneous opinion about the direction of the aircraft, that it was approaching the established flight route. As a result, the crew continued to maintain the same course, blindly trusting the data transmitted by the dispatcher and not using the instruments on board that could have indicated that the plane was flying to a mountainous area with higher peaks.
At 13:41, the aircraft reported that it had reached an altitude of 1050 meters, to which the dispatcher gave instructions to continue the flight. The crew was away from the landing course and could not fly to the marker, but at 13:42 the crew reported that the marker had passed, to which the dispatcher, without checking the location of the aircraft, gave instructions to descend to an altitude of 400 meters according to the approach pattern. The plane was not equipped with a ground proximity warning system. The sky at that time was covered with continuous clouds, the height of which the crew did not know and believed that it was the same as above the airport - 980 meters, so they intended to “break through” it, switch to visual flight and then construct an approach maneuver .
Without reducing the vertical rate of descent, the crew began to turn left to enter the landing course, when just 5 seconds later at 13:42:56, a plane flying in the clouds at an altitude of 550 meters with a left bank of 20° crashed into the spur of Mount Kukurt-Bash (height 894 meters) 23 kilometers west of Makhachkala airport, completely collapsed and caught fire. All 4 crew members and 47 passengers on board were killed. At the time of the events, this was the largest disaster involving the Yak-40.
Air crash investigation
Based on the results of the investigation, the commission presented the following conclusion:
The disaster was the result of gross violations by ATC personnel and the crew of flight rules and ATC in mountainous areas, which led to the aircraft descending below a safe altitude outside the established pattern, colliding with a mountain and completely destroying the aircraft.
Major aviation accidents are less common than, for example, fatal road accidents, but such accidents cause widespread public outcry, especially when they happen to famous people, have a large number of victims, or other exceptional circumstances. The following are several air transport emergencies that occurred in Russia in the 21st century.
Tu-154 accident near Irkutsk in 2001
On Wednesday, June 4, 2001, Tu-154 made a flight from Yekaterinburg to Vladivostok with refueling in Irkutsk.
On the day of the crash, the airliner, which received the name “Ussuriysk,” had made more than 11 thousand takeoffs and landings and had flown almost 21 thousand hours. The plane with which this plane crash happened was produced in 1986. The airliner was flown by an experienced crew, the aircraft commander had flown almost 13.5 thousand hours, the co-pilot had flown 6.8 thousand hours, worked for the airline for 20 years, the navigator had flown 6.4 thousand hours, the flight engineer had flown 954 hours, all on Tu- 154".
There were 145 people on board, including 9 crew members. Most of the passengers were citizens of the Russian Federation; there were also 12 Chinese citizens on the flight.
The flight proceeded as usual until landing at Irkutsk airport. The catastrophic situation developed rapidly (only 15 seconds). All attempts by the aircraft crew to level the plane were unsuccessful due to lack of altitude. The plane went into a tailspin and fell to the ground. The Tu-154 disappeared from radar at 02:08, and already at 03:25 the wreckage was discovered 22 km from Irkutsk.
July 5, 2001, the day after the tragedy, was declared a day of mourning in the Russian Federation. Everyone on board died. The investigation into the plane crash did not last long, as all three recorders were found immediately. Experts blamed crew errors as the cause of the crash.
Terrorist attacks "Tu-154" and "Tu-134" in 2004
In August 2004, almost simultaneously, explosive devices were detonated on the Tu-154 (Siberia Airlines, route Moscow - Sochi) and Tu-134 (Aviaexpress, Moscow - Volgograd), which were carried on board by suicide bombers. Both planes crashed, forty-six people died in the Tu-154, forty-four people died in the Tu-134. The first flight departed from Domodedovo at 21:25, the second at 22:00, also from Domodedovo. The T "u-134" was the first to disappear from the screens (at 22:56), and a few minutes later the connection with the "Tu-154" was also lost.
The wreckage and remains of passengers who died in the plane crash with the Tu-134 were discovered in the Tula region at 2:00, and the Tu-154 at 08:15 in the Rostov region. The investigation quickly established the cause of the crash.
The causes of the plane crash were the same - a terrorist attack. It was committed by Chechen suicide bombers A. Nagaeva and S. Dzhebirkhanova. The terrorists assembled explosive devices already on board, in the toilets. The power of the explosions could have been small. As a result of the terrorist attacks, everyone on board both one and the other aircraft was killed. The total number of victims was 90 people.
A-320 crash on May 3, 2006
Another plane crash in Russia occurred on May 3, 2006 in Sochi. The plane of the national air carrier of Armenia was flying from Yerevan to Sochi. There were one hundred and five passengers and eight crew members on board. Most of the passengers and all crew members were citizens of Armenia, there were 26 Russians on the plane, and one Ukrainian and one Georgian were also on this flight. Among the passengers was also Arthur Tumasyan, one of the authors of the Comedy Club show.
The flight took off from Yerevan and headed for Sochi, the flight proceeded as usual. The weather in Sochi was bad, so the crew decided to return to Yerevan. Later the decision changed: they decided to land in Sochi. Moreover, the weather was better than the landing minimum. However, the plane fell into the Black Sea and was destroyed. Everyone on board died.
According to the official report of the Interstate Aviation Committee of Armenia, the cause of the disaster was the incorrect actions of the pilots and difficult meteorological conditions during the approach. Soon after the plane crash, rumors appeared in the media that there were criminal elements on board and that there was even a shootout. These opinions were subsequently refuted by the official report of the IAC.
A-310 accident at Irkutsk airport on July 9, 2006
In July 2006, the plane flew from Moscow to Irkutsk. The flight proceeded normally, but after landing the crew was unable to stop on the runway and crashed into the garages. There were 203 people on board (8 of them were crew members), 125 passengers died. Of the survivors - 78 people, 63 were injured.
Two flight attendants especially distinguished themselves, who, at the cost of their own lives and health, saved about 50 passengers of the crashed flight. Andrei Dyakonov, according to the testimony of surviving passengers, acted strictly according to instructions. When the fire started, the young man knocked down the door of the plane and began to literally push people out. When the ship began to fall apart, the flight attendant apparently did not have time to jump out. Andrei Dyakonov died and was posthumously awarded.
The emergency exit was also opened by Victoria Zilberstein, a twenty-two-year-old flight attendant. She got out from under the rubble of seats and luggage, got to the emergency hatch and began to let people out. Victoria herself was the last to leave the plane through this hatch. The girl suffered a concussion, but, having recovered, was able to start working again.
Experts blamed the cause of the crash, like many other aviation accidents, on the wrong actions of the pilots. The criminal case was closed due to the death of the suspects. During the investigation, the cause was also cited as equipment malfunction and other factors, which cannot be reliably established.
Crash during landing in Perm in 2008
In the Boeing 737 crash, which occurred on September 14, 2008, 11 km from Perm airport, everyone died - only 82 people. The flight was flying along the Moscow - Perm route, but not far from its final destination the plane crashed to the ground and was destroyed. This incident was the first crash of a Boeing 737 on Russian territory.
The fall of the Polish presidential plane
The crash of the Tu-154 in Smolensk was a catastrophe in which almost the entire high military command of Poland, the president and his wife, and famous Polish politicians died. The delegation was heading to Russia to attend mourning events on the occasion of the anniversary of the shooting in Katyn.
The crew of the plane, as it turned out, was not sufficiently prepared for the flight. In fact, only the flight engineer on the day of departure had a valid permit to fly the Tu-154. In addition, the crew did not have up-to-date meteorological data for the Smolensk airport, as well as exact coordinates. Subsequently, some media outlets cited pressure on the pilots from the President of Poland as one of the reasons for the disaster. There was a previous case when the president demanded to change course, but the pilot refused to comply with this request, since otherwise the passengers would be in danger.
There were ninety-six people on board, eighty-eight of them passengers. On this flight, as already mentioned, were the President of Poland L. Kaczynski and his wife, the head of the chancellery, the Deputy Minister of Foreign Affairs, the Deputy Minister of Culture, the head of the National Bank, the head of the National Security Bureau and other prominent political, public, military and religious figures. Lech Kaczynski’s brother was also supposed to be on board, but he was unable to fly due to his mother’s sharply deteriorating health condition.
The flight proceeded normally, and the landing approach was also carried out correctly at first. The plane collided with trees, but, as the commission later established, the conditions were such that even if the aircraft had not encountered an obstacle, a disaster would still have occurred within a few seconds.
According to the final investigation report, the causes of the disaster were difficult meteorological conditions, pilots ignoring warning signals and descending below the minimum altitude, i.e., crew error. In addition, imperfections in the equipment installed on board were revealed.
Crash of the Yak-42 with Lokomotiv on board
The plane crash, which killed the players of the Lokomotiv hockey club, occurred near Yaroslavl on September 7, 2011. The crash occurred during takeoff; the aircraft was in flight for only a few seconds. The liner collided with the lighthouse, crashed into the earth's surface and collapsed. Only one person survived the crash - an equipment engineer. All others (eight crew members and thirty-seven passengers) were killed. Due to the death of the hockey team, Lokomotiv dropped out of the KHL in 2011-2012. Experts called the cause of the crash an error by the pilots: one of them pressed the brake pedals during the take-off run.
Disaster at Kazan airport in 2013
The Boeing 737, owned by the Tatarstan company, was flying from Moscow to Kazan on November 17, 2013. The landing approach was carried out automatically; at some point, signals were heard in the cockpit indicating the maximum proximity to the ground for this altitude. All 50 people on board died. The crash was the largest in terms of casualties in 2013. At the moment, this is the last disaster on regular lines in Russia.
The fall of the Tu-154 of the Russian Ministry of Defense in Sochi
On December 25, 2016, members of the Academic Ensemble flew to the Khmeimim airbase in Syria to congratulate Russian military personnel on the upcoming New Year holidays. Refueling was initially planned in Mozdok, but due to unfavorable weather conditions it was moved to Sochi. The airliner successfully took off from Sochi, but disappeared from radar within two minutes. The aircraft crashed into the Black Sea. All the people on board (eighty-four passengers and eight crew members) were killed.
An aircraft accident is characterized by certain circumstances that usually end in tragedy. In this case, a technical malfunction of the aircraft and crew errors or overload probably led to the disaster. This is exactly what the commission found. There is also a version that there was a stranger in the cockpit who did not have permission to fly.
Plane crashes in Russia in 2017
The list of aviation accidents for 2017 in Russia includes only 15 incidents. This is less than last year's figure by 53.1%. In 2016, the number of disasters and aviation accidents that occurred in the Russian Federation was 32 cases. Only 22 people died in aircraft accidents in 2017. Compared to the previous year, a decrease of 81.1% was recorded (in 2016 - 119 victims). The number of victims also decreased significantly: 29 people in 2017 versus 132 in 2016. According to official data from the Ministry of Emergency Situations, most disasters in previous years occurred in the Southern and Far Eastern (twenty-four percent each), as well as in the Central (seventeen percent) Federal District. Most aircraft crashed in the Southern Federal District (33%), helicopters - in the Far Eastern Federal District (45%).
Twenty-five years ago, the largest plane crash in the history of aviation in Tajikistan occurred in Khorog. Sputnik Tajikistan remembers this tragic date.
Flight of the Yak-40 - everything went according to plan
It was piloted by a crew that included commander Mels Siyarov, co-pilot Yuri Demin and flight mechanic Nizomiddin Buriev.
Flight attendant Kayumov also worked in the cabin, and Evgeniy Babajanov was the squad’s navigator.
Civil war in Tajikistan
At that time, there was a civil war in Tajikistan, and Khorog was captured by militants. Several hundred civilians gathered at the airport, wanting to leave the city on the same Yak-40 flight.
During the landing, armed militants intervened in the situation. Threatening with weapons, they began to direct the seating process at their own discretion, trying to put as many people on board as possible. The crew of the plane tried to reason with them, pointing out that the plane was not designed for such a number of passengers, but in vain.
A total of 81 passengers boarded the plane, although the plane was designed for only 28 seats. This is what caused the plane crash.
The board turned out to be heavily overloaded - the maximum take-off weight was exceeded by as much as three tons. The crew refused to fly. However, after the threat of execution, the pilots were forced to agree.
The dispatcher, who was supposed to control the landing, was not even allowed near the ramp by armed people.
However, not everyone was able to board the plane: the militants sent some people back to the airport.
Yak-40 plane crash in Khorog
The overload was felt during the first minutes of takeoff. A plane crash was inevitable. The plane covered almost the entire runway - 1,629 meters. The Yak-40 was unable to get off the ground and rolled out of the runway.
After this, the accelerated aircraft crashed into the parapet of a shallow ditch with its left strut, and then collided with a stone 60 cm high.
After another 30 meters, the left wheel of the Yak-40 fell into a ravine and collapsed, and the right one hit a meter-high concrete pillbox, after which the plane with all the passengers crashed into the ravine of the Pyanj River.
Consequences of the Yak-40 plane crash
The plane crash killed 82 passengers and crew members, including 14 children. The bodies of 80 dead were found directly at the site of the Yak-40 crash. Surprisingly, six people were found alive.
Two crew members later died in hospital, in particular 36-year-old flight mechanic Nizomiddin Buriev, who was taken to a hospital in Dushanbe in serious condition. Dozens of people from all parts of the city came to say goodbye to him.
This is the largest disaster on the territory of Tajikistan and in the history of Yak-40 aircraft. Immediately after the incident, all passenger flights in Khorog were stopped until the end of the civil war.
Research at the State Research Institute of Civil Aviation allowed us to establish:1) The primary failure that led to the disaster was the disconnection of the parts of the screw pair of the stabilizer transfer mechanism (MTS) in flight. The removal of the nut 42M5180-42 from the screw 42M5180-65 occurred without their mutual rotational movement, began under the influence of operational loads and caused static destruction of the upper stop 42M5180-72 of the MPS screw. After the failure of the MPS screw pair, which simultaneously served as the front power support of the stabilizer, perceiving external loads, the destruction and separation of parts of the stabilizer from the aircraft followed under the influence of excess loads that arose as a result of the deflection of the stabilizer at large positive angles and a sharp increase in speed pressure in excess of permissible values.
2) The reason for the separation of the parts of the MPS screw pair was the almost complete wear of the threads of the nut 42M5180-42, due to the imperfection of the MPS design:
a) the MPS friction screw pair is operated under conditions of continuous running-in - a continuous wear process of a nut made of BrOF10-1 bronze;
b) MPS on Yak-42 aircraft is subject to external influences that cause corrosion and contamination of parts and lubricants, which increase wear conditions.
3) An analysis of the design of the Yak-42 aircraft and other types of aircraft shows that the main disadvantages of the Yak-42 aircraft design are:
a) imperfection of the MPS power circuit - the transverse axis of the cardan nut 42M5180-42 is located significantly (37 mm) lower than the longitudinal one. This predetermines the operation of the nut when transmitting forces from the stabilizer to the keel in a position of unstable equilibrium, creating a misalignment in the “screw-nut” friction pair. In this case, intensive wear, corresponding to the beginning of the running-in of the friction pair, begins anew after each activation of the MPS backup system;
b) the designer’s drawings do not directly indicate the maximum size of the mismatch between the point of intersection of the cardan axes and the nut axis, and the importance of maintaining this size within acceptable limits is not noted. This led to the fact that on the MLS of the Yak-42 aircraft No. 42529, the indicated discrepancy turned out to be very large (0.4 mm) and significantly increased the effect of misalignment during the operation of the MLS friction pair;
c) the MPS backup control unit is fixed so that its mass can enhance the effect of misalignment of the MPS screw pair parts;
d) the nut of the MPS screw pair is not duplicated in case of wear of its threads;
e) sleeve bearings are used in the axes of the MPS cardan shafts, creating a relatively large frictional moment, which increases the lateral load of the nut;
f) the design does not provide effective protection of MPS parts and assemblies from corrosion and contamination during operation;
g) the drawing provides for the use of CIATIM 221 lubricant for MPS units, which does not have satisfactory performance properties.
4) Intensive wear of the material of the nut 42M5180-42 could be facilitated by increased vibration loads in the area where the MPS is installed (there is no actual data on the vibration load of the MPS on Yak-42 aircraft).
5) Checking the condition of the parts of the MPS screw pairs removed from the Yak-42 aircraft in service showed that wear of the thread of the nut 42M5180-42, which threatens a similar failure of the MPS if they continue to be used, is a common defect characteristic of this design.
6) The inspection of the MPS required by the maintenance regulations every 300 flight hours does not allow detecting signs of wear on the MPS propeller pair using the current technology.
An analysis of the operating experience of the Yak-42 aircraft fleet showed that during operation, a large number of defects were identified on them, indicating low quality production and design flaws of the aircraft. Over the 12 months of operation of the two Yak-42s, 225 claims of complaint were submitted to LOAO. The number of defects in form F2 (600 hours) compared to F1 (300 hours) increased by 1.5 times. Airplane No. 42529 is equipped with a stabilizer and MPS parts with the serial number of another aircraft (0204, No. 42530). On all removed MFAs of other aircraft manufactured by PO Box B-8122, there are no nut and screw markings indicating their belonging to a specific mechanism. The passports for the Ministry of Railways do not indicate their serial number. This indicates low technological discipline at the enterprise. On aircraft No. 42529 and other aircraft, about 70 deficiencies were identified in the installation of the control system, communications, instrument wiring harnesses and radio equipment. A significant number of airframe defects were identified.
Conclusions:
1) The destruction of the aircraft in the air is caused by the action of off-design aerodynamic loads due to the sharp decline of the aircraft.
2) The sharp descent of the aircraft is caused by an almost instantaneous spontaneous movement of the stabilizer behind the mechanical stop, which led to the creation of an uncompensated diving moment, the aircraft reaching large negative overloads and accelerating the speed beyond the permissible limit.
3) Spontaneous movement of the stabilizer occurred due to the disconnection of the MPS screw pair parts in flight due to almost complete wear of the thread of the nut 42M5180-42, due to the structural imperfection of the mechanism.
4) An inspection of the Yak-42 aircraft fleet showed similar wear on the nut on other aircraft.
5) The inspection of the MPS provided for in the technical maintenance regulations does not allow us to detect signs of wear on the screw pair using the current technology. During the period of operation of the Yak-42 aircraft, there were no comments on the condition of the MPS and other elements of the stabilizer control system.
6) A large number of defects discovered during the maintenance of Yak-42 aircraft indicate low quality production and existing design flaws in the aircraft.
7) The Yak-42 aircraft stabilizer control system does not comply with NLGS-2 airworthiness standards.
