The Su-57’s uncontrolled flight in the sky: what ‘killed’ the aircraft?

Two main versions of the loss of the aircraft are currently being considered: the human factor and the failure of airborne systems

Source: Stmed.net

The fifth-generation Russian fighter Su-57, which crashed on December 24, 120 km north of Komsomolsk-on-Amur, was planned to be transferred to the airborne forces by the end of the year. This was reported to Izvestia by sources in the military department. The cause of the incident could be a failure of the control system during the test flight. This version is considered as one of the priority by a special commission, which is to determine what led to the state of emergency. The experts should be helped in this by the data of the flight recorders and the report of the Su-57 pilot, who successfully ejected and was not injured. By a fortunate coincidence, there were no casualties or destruction at the crash site.


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Electronic rejection

As sources familiar with the situation in the military-industrial complex and military department told Izvestia, two main versions of the loss of the aircraft are currently being considered: the human factor and the failure of airborne systems.

One of the possible reasons for the emergency, the interlocutors called the failure of the electro-remote control system of the aircraft (EDSU). A system could fail as a result of a failure of one of its components or a software failure.

With the help of the electronic control system, the aircraft is controlled, explained to Izvestia Hero of Russia, test pilot Oleg Mutovin.

During the flight, the EMDS transmits the pilot’s control movements or automatic control systems with the help of electrical signals to the controls – aerodynamic wheels or thrust vector deviation devices. Therefore, in the West, the acronym FBW is adopted for it – Fly-by-Wire, “flight control by wire.” It began to be introduced in the 70s and is currently used not only on military aircraft, but on civilian airliners and even on some types of helicopters.

According to the expert, the EMF has many advantages – for example, it eliminates the need to use rigid rods between the controls and steering surfaces. This allows you to seriously save in weight and in the volume of the glider, which is especially appreciated in aviation. Directly steering surfaces reject electric drives. Using EDSU allows combat aircraft to achieve high maneuverability and efficiency, and civilian – to improve efficiency and productivity.

“The Su-57 has a multi-stage system of protection against piloting errors,” a military-industrial complex representative familiar with the situation told Izvestia. – It does not allow you to “drive” the plane into critical flight modes. Due to the on-board computers and engines with a variable thrust vector, the car can be deduced from the most difficult situations. It is enough for the pilot to press the button, and the control system will return the machine to horizontal flight.

A complete failure of such a system at present is a rarity, said Oleg Mutovin, since usually control signals are transmitted simultaneously on four channels. Failure of one of them or receipt of false information on it is a reason for a restart. If two channels fail, it is better to return to the airfield, the expert emphasized.

In case of failure of the three channels, the pilot must switch to the Direct Communication mode, as it is called on combat aircraft, the pilot controls the machine manually. The control algorithm becomes simplified, but flight is supported. An experienced pilot will get out of this situation without problems, the expert noted.

Another possible reason could be the failure of motor automation. This system regulates the operating modes of the Su-57 engines and fuel supply.

One and a half hours to save

After an emergency occurred at 14:14 Moscow time (11:14 local time), the fighter pilot ejected. Ten minutes later, the on-duty factory helicopter Mi-8 of the search and rescue service flew to the crash site. An-30 aircraft and another helicopter from the Khabarovsk airfield were ready to join the search and rescue operation, but their help was not required. Less than an hour and a half after the bailout, the test pilot was delivered to Dzemgi airfield.

Flight recorders found on the same day. They are in satisfactory condition. As a source from the plant told Izvestia, a new test equipment was also installed on the aircraft, which transmitted the developers the basic parameters of the flight and the operation of on-board systems in real time. This information, along with the data of the “black boxes” will help accelerate the search for the causes of the flight accident.

The exact causes of the incident will be established by the commission, which has already begun work. The aircraft has not yet been officially handed over to the Aerospace Forces and remained in the register of experimental aircraft. Therefore, in accordance with the law, the Ministry of Industry and Trade of Russia took up the investigation. According to the press service of the department, Deputy Minister Oleg Bocharov will head the investigation. According to Izvestia, the commission will also include representatives of the High Command of the Air Forces, specialists from the UAC, Sukhoi Design Bureau, Gromov Flight Research Institute and the 929th State Flight Test Center of the Ministry of Defense.

What awaits the Su-57 series

The accident of the fifth-generation Russian fighter for the first time led to the loss of the aircraft. In June 2014, the engine of one of the prototypes of the Su-57 caught fire during tests in Zhukovsky near Moscow. The board received serious damage, but after repair it was possible to return it to the flight test program.

In late November, Deputy Defense Minister Alexei Krivoruchko said that the first fifth-generation serial fighter will be handed over to the Ministry of Defense by the end of 2019. According to Izvestia sources in the military department, this particular specimen – an airplane with tail number 01 blue and serial number 51001 – crashed near Komsomolsk-on-Amur. In 2020, another machine of this type was supposed to enter the VKS – it was planned to seriously increase the pace of aircraft production in subsequent years. In total, by the end of 2027, under the existing contracts, the airborne forces should receive 76 Su-57s, which will be equipped with three aviation regiments.

At the same time, the incident is unlikely to affect plans for serial production of the fighter, military expert Vladislav Shurygin is sure.

“The plane was worked out long ago, passed flight tests and put into service,” he explained to Izvestia. – “And not a single car is safe from an emergency. You can recall how the F-22 fell during the test phase, what problems the F-35 had. This is an absolutely ordinary standard situation. The reasons will simply be established and measures taken,” concluded Vladislav Shurygin.

Serial production of the Su-57 officially started in May 2019. Initially, the current state armament program for 2018–2027 provided for the construction of only 16 of the latest fighters. By personal order of Vladimir Putin, these plans were radically revised upward. A large series allowed the Ministry of Defense to negotiate with the United Aircraft Corporation to reduce the price of the newest and most expensive Russian fighter by 20%.

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