The plane itself give up, not the people.
As it became known to Kommersant, experts have established the causes of the crash of the experimental Il-112V that happened in Kubinka near Moscow five days before the start of the Army-2021 forum. A critical situation on board was provoked by an engine fire, but the plane went into an uncontrolled side roll, which turned into a rollover, due to the breakage of the right aileron thrust destroyed by fire. The pilots in this situation could do absolutely nothing; they also had nothing to say to each other, so the crew died in silence.
Experts of the Ministry of Industry and Trade and the Interstate Aviation Committee (IAC) found that the development of the disaster began with the loss of gas-dynamic stability of the right engine of the Il-112V. The subsequent surge, accompanied by pops and flame emissions, probably led to the partial destruction of the turbine, and its fragments, in turn, could kill the fuel lines located nearby. To determine the exact cause of the fire of the transport vehicle, specialists will have to wait for the results of the examinations that have already been appointed, but, anyway, a few minutes after takeoff, a powerful "kerosene" fire appeared in the internal cavities of the gondola and the right wing of the Il-112V.
It is interesting that the first fire was noticed not by the pilots, but by the dispatchers of the Kubinka airfield, from which the board that caught fire soon took off. The crew was immediately informed about the problem by radio, but this, as it turned out, was not necessary. The danger warning board has already lit up in the cockpit and the so — called first stage of the fire extinguishing system has worked automatically-a fire extinguishing foam composition was released into the gondola from a high-pressure fire extinguisher cylinder located next to it.
The crew reacted to the alarm promptly: realizing that the foam attack was idle, the pilots had already manually activated the second stage of the fire extinguishing system, which also did not reach the target.
As sources close to the investigation explained to Kommersant, both Il-112V fire extinguishing systems were focused primarily on engines, so the foam formed from carbon dioxide and inert gases filled mainly the nacelle of one of them, while the fire had already spread to the inner cavity of the wing. Meanwhile, there was nothing else to fill the fire with. According to the interlocutor of Kommersant, the manufacturer has provided only two fire extinguishers for each engine of the transport vehicle, while, for example, in civil aircraft of PJSC Il, fire extinguishing is provided in six queues.
The pilots, therefore, had no choice but to return to the departure airfield and make an emergency landing, which they requested. The experienced crew, as experts say, acted smoothly and quickly. The commander, without the slightest signs of panic, ordered the co-pilot: "Turn off", then - "Fly", and he just calmly reported on the execution, saying that the burning engine was safely stopped, and the blades of his propeller were installed "downstream" and did not interfere with the movement of the aircraft. The crew managed to position the rudders of the aircraft and select the mode of the only working engine in such a way that, despite the raging fire and asymmetric thrust, the car went towards the airfield on an almost perfect straight course. Describing the video recording of the last seconds of the Il-112V flight, made by a random eyewitness of the tragedy, experts even called it a "slip". In their opinion, in this mode, the pilots would probably have landed a burning transport in Kubinka, which was only one and a half to two kilometers away.
However, the desperate struggle of people for survival, according to experts, was in vain, because the plane itself "gave up".
At the 45th second of the flight after the fire started, the temperature in the right wing cavity reached 600 degrees, after which, as the investigators found, the duralumin aileron thrust going inside collapsed. The temperature of 650 degrees is critical for duralumin D16, from which the thrust and most other parts of the aircraft were made, but already at 600 degrees the duralumin tube on hinges holding the right aileron in the lowered position, as experts say, lost elasticity and "flowed".
Due to the destruction of the thrust, the aileron, which helped the pilots to ensure the straight flight of the Il-112V, got into a neutral position, located along the plane of the wing, and the car began to roll to the right and lower the nose. The roll increased slowly at first, but the pilots, as investigators believe, already at the moment of the thrust breakage realized that the process that had begun was irreversible. The pilots could not somehow influence the behavior of the aircraft; they apparently did not consider it necessary to comment on the situation either, so they simply remained silent. The last turn of the transport lasted only three seconds — the increasing right bank ended in a coup and a fall.
Experts who have dealt with this tragedy say that no pilot in the world could have taken the plane out of the roll in such conditions, noting that by coincidence the accident occurred in the forest, and not in the Patriot Park, over which the Il-112V demonstration flight was planned.
Most experts believe that the reason for the tragedy is the unpreparedness for the flights of the first experimental model of a military transport vehicle and the possible haste with its commissioning.
Flight No.0001, issued by the Voronezh Joint-Stock Aircraft Construction Company (VASO), was the first and only "flying" aircraft of this type in the world (another copy of the Il-112B has so far been tested only on the ground). During its short history, the first number managed to take to the air 23 times, making 22 landings at the same time. Experts note that almost all flights of the crashed aircraft were short, five-minute, and from March 2019 to March 2021, it did not fly at all due to identified technical flaws that aircraft designers had to eliminate. The specialists made the most claims to the TV7-117ST engines produced by JSC "UEC-Klimov".
However, despite all the problems that have arisen, they decided to show the experimental copy first at the International Aerospace Salon (MAKS), held in July, and then to coincide the show with the International Military Technical Forum "Army-2021", held on August 22-28. The rush, experts believe, created the conditions for a catastrophe, but it is not yet clear whether this opinion will become the official conclusion of the commission of the Ministry of Industry and Trade. In any case, as an informed source of Kommersant explained, the investigators have already been tasked to find out in detail whether the crew made mistakes when performing the approach.