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Two Soviet An-26 airplanes carrying out passenger flights from Kostroma to Saint-Petersburg had been flying with large dents for ten years, with a government agency appearing to turn a blind eye to the damage.
Staff from Russia’s federal transport inspection agency, Rostransnadzor, only saw the damage during a recent review of the Kostroma Air Company, reported the Telegram channel “Aviatorshchina” with reference to the agency’s classified documentation. Aviatorshchina’s administrator told The Insider that the channel had the documents in its possession, but refused to reveal them.
The fleet of the Kostroma Air Company has four such aircraft – dents were found on two of them. The two An-26 aircraft fly between Kostroma and St. Petersburg three times a week.
Two dents were found on the airplane with tail number RA-26113, which is almost 40 years old, «Aviatorschina» wrote. The first dent is located on the lower right side of the air intake of the left AI-24 engine, measuring 100x80 mm with a depth of up to 7 mm. The second dent, located on the nose of the right stabilizer half, measures 100x25 mm with a depth of 7 mm.
The aircraft was bought by the Kostroma-based company – dents included – in 2016 from the Yamal airline, according to the Telegram channel. The dents were recorded at the end of May 2010 and the beginning of November 2012.
The second RA-27210 aircraft is 45 years old and has a dent measuring 150x170 mm and up to 30 mm deep on the lower fairing of the side rail, located in front of the ramp. According to the manufacturer’s operational documentation, such damage would render the plane inoperable. Rostransnadzor banned both aircraft from flying until the damage would be repaired.
Rostransnadzor also found out that almost half of the company’s 15 pilots did not have the necessary training – including simulator training – to man aircraft. Internal qualification inspections were also not fully completed.
The agency began inspecting the Kostroma Air Company after the recent crash of the airline’s Mi-2 medical aviation helicopter with five people on board. According to preliminary data, one person died in the incident – a 67-year-old patient who was being evacuated by the helicopter, while two paramedics and two pilots were injured.
As an anonymous aviation expert explained to The Insider, operating an aircraft with such hull damage is a major threat to flight safety.
“Firstly, if the geometry of the cladding is disturbed during flight, there will be a disturbance in the flow of air, unnecessary drag will be created, and the aircraft will need more fuel, which will also increase emissions into the atmosphere. Secondly, if the dent is very severe, the integrity of the hull will be compromised – over time, microcracks or even through damage can occur, which can easily lead to the complete destruction of the hull in [the location of the dent]. Failure of material due to fatigue is always an issue, and this is fraught with the worst consequences. Thirdly, in case of cladding damage, any elements of fasteners, joints, aggregates, wiring under the cladding and so on – can also be damaged. If the nacelle cladding is deformed, there could be damage to the propulsion system, if there’s damage to fuselage cladding, there could be damage to the control system components, or the wiring, or the fuel system, and so on.
Until you take that piece of cladding off and see if there’s any damage inside, you won’t know how critical it is. You cannot, in principle, operate an airplane with severe hull damage. If the hull is dented by a few centimeters, there’s no telling what could be damaged, either in the hull itself or inside the airplane. This is quite critical damage, you can't operate the airplane with it. And the fact that the airline has been flying for years with such damage to the hull is simply a crime.”
A second aviation expert also noted that extra layers of ice could form in such dents, creating problems for the de-icing system. The expert stressed that issues should be raised with Rostransnadzor’s inspectors, who had deemed the plane airworthy for the better part of a decade, with the dents only being noticed after the fall of a Kostroma Air Company helicopter.
“In fact, the dents are not critical for immediate flight shutdown for safety reasons. But such damage should be repaired, if not at the first opportunity, then at least as part of routine repairs. Any damage to the outer shell is at least a potential threat. It may not be a hazard on its own, but when combined with other factors, it [can] lead to tragedy. For example, more ice may form in the dent on the wing than usual, and the de-icing system can no longer deal with it in time. Or that larger-than-usual chunk of ice after separation from the airplane could damage the elements of the altitude rudders, and so on. That’s why the operations manual outlines permissible damage. Why they decided to fix it now – that's more of a question for the inspectors, who conducted regular inspections for 10 years and issued certificates of airworthiness for this crumpled plane.”