On July 5, 2024, an An-2 aircraft, registration RA-40983, operated by LLC 'Aviation Company KRЫLYA TAYGI', was performing aviation forestry work near the settlement of Sosnovo-Ozersk in the Republic of Buryatia, Russia. The flight was dispatched to monitor a smoke plume detected by the Remote Forest Fire Monitoring System near the border of Zabaykalsky Krai and Yravninskoye forestry.
Technical research conducted by the Interstate Aviation Committee focused on the failure of a paronite gasket located under the housing of the constant speed governor drive. The investigation determined that while the gasket was manufactured according to the correct drawing for a series 15 constant speed governor drive, it had been installed on a series 16 drive manufactured in Poland.
The investigation revealed a fundamental design discrepancy between the components. The oil channel in the engine nozzle flange is circular, whereas the oil channel in the constant speed governor drive is elliptical. This mismatch caused a partial overlap of the oil channels.
Under the high-pressure, high-temperature oil environment, the paronite structure experienced swelling, leading to the failure of the gasket. The investigation concluded that the mismatch between the gasket's design and the specific governor drive housing constitutes a design flaw.