What happened
On a scheduled cargo flight from Komsomolsk-on-Amur Airport to Keperveyem, an Antonov AN-12 was transporting 17.43 tons of cargo along with two passengers and nine crew members. The aircraft, operating as flight LN9209, departed Komsomolsk-on-Amur at 14:37 local time, with a planned stop in Magadan.
While cruising at an altitude of 7,500 meters approximately 430 km northeast of the departure airport, the crew notified air traffic control of a fuel leak occurring in the number one engine. The flight crew requested a descent to 6,600 meters and sought permission to return to Komsomolsk-on-Amur. During this period, the number one engine caught fire, prompting the crew to declare an emergency and initiate a rapid descent.
The aircraft subsequently became uncontrollable and struck a mountain slope roughly 82 km southwest of Omsukchan. The impact caused the aircraft to disintegrate, with wreckage discovered at an altitude of 1,006 meters the following day. There were 11 fatalities among the occupants.
Findings
Investigations determined that a fire originated in the tail section of the number one engine nacelle and spread toward the wing. This fire was likely fueled by a leak from a fuel line connection at the low-pressure fuel pump, with the leaking fuel igniting upon contact with hot engine components. After the crew shut down the engine and feathered the propeller, the aircraft lost longitudinal roll control. This loss of control was attributed to the load-bearing characteristics of the left wing and potential damage to the aileron control wiring, leading to an uncontrolled roll to the left.
Several contributing factors were identified:
- The fire suppression system failed to extinguish the flames during the early stages of the fire.
- A lack of specific checklists or guidelines in the flight manual for managing engine nacelle fuel leaks caused a delay of over two minutes before the engine was shut down.
- Difficulties in selecting an emergency landing site were caused by the mountainous terrain, low cloud cover, and the rapid progression of the fire.