On August 6, 2018, an Mi-2M helicopter, registration RA-15629, operated by OOO 'Aviaкомпания "Velthal - Avia"' was conducting a flight to survey an oil pipeline and prepare maps for an upcoming aerial survey. The flight involved several legs, including a takeoff from the 'Nagorny' landing site following a refueling stop at the 'Osinnik' landing site.
Six minutes after departing from the 'Nagorny' landing site, the aircraft's left engine unexpectedly shut down. The pilot-in-command made the decision to perform a forced landing at a landing site selected from the air. There were no injuries or fatalities reported following the incident.
The investigation into the failure of the GTD-350 engine on RA-15629 determined that the engine shut down due to a malfunction in the electromagnetic valve. Specifically, the third core of the valve jammed in the open position.
Technical analysis revealed that the jamming was caused by foreign metallic particles entering the gap between the valve core and the coil housing. These particles originated from the end surfaces of the valve core and the associated coil due to improper mechanical processing during the manufacturing stage.