Two Soviet An-26 aircraft, which operated passenger flights on the Kostroma-St. Petersburg route, flew for ten years with large dents, but the inspection departments did not notice this. Rostransnadzor inspectors saw damage only during a recent inspection of the Kostroma Aviation Enterprise. This is reported by the Telegram channel "Aviatorshchina" with reference to the closed documentation of the department. The channel's administration told The Insider that it had the documents, but refused to show them.
In total, there are four such aircraft in the fleet of Kostroma Aviation Enterprise, dents were found on two of them. They operate flights only between Kostroma and St. Petersburg three times a week.
On the plane RA-26113, which is almost 40 years old, two dents were noticed, writes "Aviatorschina". The first one is on the lower right side of the air intake of the Ukrainian-made AI-24 left engine, its size is 100 x 80 mm and its depth is up to 7 mm. And the second – on the toe of the right half of the stabilizer – 100 x 25 mm and in depth – up to 7 mm.
The plane was bought by the company already with dents, according to the Telegram channel, in 2016 from the Yamal airline. The dents were entered into the airframe skin condition list at the end of May 2010 and the beginning of November 2012.
The second aircraft, RA-27210, is 45 years old and was found to have a dent measuring 150 x 170 mm and up to 30 mm deep on the lower fairing of the side rail located in front of the ramp. According to the developer's operational documentation, it is impossible to fly with such damage. Rostransnadzor banned these aircraft from flying until the damage was repaired.
Rostransnadzor also found out that out of 15 pilots, almost half did not undergo the necessary training, including simulator training. In addition, qualification internal audits were not fully passed.
Rostransnadzor began to check the Kostroma Aviation Enterprise after the recent crash of the Mi-2 air ambulance helicopter in Kostroma. There were five people on board. According to preliminary data, one person died during the incident – a 67-year-old patient who was evacuated by a helicopter, and two paramedics and two pilots were injured.
As an anonymous aviation expert explained to The Insider, operating an aircraft with any violation of the aerodynamic skin profile is a threat to flight safety.
“Firstly, if the skin geometry is violated during the flight, air flow will be disturbed, excess resistance will be created, and the aircraft will need more fuel, which will also increase emissions into the atmosphere. Secondly, if the dent is very strong, then the integrity of the skin will be at risk – there, over time, microcracks or even through damage may appear, which can easily lead to the already complete destruction of the skin in this place. Fatigue failure of the material in this case has not been canceled, and this is fraught with the worst consequences. Thirdly, in case of damage to the skin, any fastening elements, assemblies, assemblies, wiring under the skin, etc. can be damaged. If this is damage to the engine nacelle, then the elements of the power plant may be damaged; if it is the fuselage, there may be damage to the control system rods, wiring, fuel system, and so on.
Until you remove this piece of skin and see if there is any damage inside, you will not understand how critical this is. In principle, it is impossible to operate an aircraft with serious damage to the skin. If the skin is dented a few centimeters, then you never know what could be damaged there, both in the skin itself and inside the aircraft. These are quite critical damages, the aircraft cannot be operated with them. And the fact that the airline has been flying for years with such damage to the skin is just a crime.”
The second aviation expert also noted that more ice could form in such dents, this would be a problem for the anti-icing system. He also noted that questions should also be asked to the inspectors of Rostransnadzor, who conducted inspections for ten years, issued airworthiness certificates, but dents were noticed only after the helicopter of the operating airline crashed.
“In fact, the dents are not critical for the immediate stop of flights for safety reasons. But such damage must be eliminated, if not at the first opportunity, then at least as part of scheduled repairs. Any damage to the outer skin is at least a potential threat. By itself, it may not manifest itself as a dangerous factor, but when combined with other factors [may] lead to tragedy. For example, in a dent on a wing, more ice than usual may form, and the anti-icing system will no longer cope with it in time. Or this larger than it should be, a piece of ice after separation from the aircraft can damage the elements of the elevators, and so on. Therefore, the permissible damage values are written in the operating manual. Why they decided to eliminate them only now – there are more questions for the inspectors of the Federal Air Transport Agency, who for 10 years have been conducting regular inspections and issuing a certificate of airworthiness for this crumpled aircraft.