Investigation Summary
The accident flight originated in Komsomolsk-on-Amur with a scheduled stop in Magadan. After departing Magadan for the final leg to Keperveyem, the crew noticed a fuel leak while cruising at 7,500 meters. The leak originated near the low-pressure fuel pump of the number one engine. Approximately two minutes elapsed between the detection of the leak and the engine shutdown, a delay attributed to the lack of specific checklists for fuel leaks within the engine nacelle in the An-12 flight manual. During this interval, the leaking fuel ignited upon contact with hot engine components. The resulting fire spread from the aft nacelle to the wing structure. As the crew initiated an emergency descent, the intense heat caused the left wing to lose its load-bearing properties and likely severed the left aileron control rods. This led to an unrecoverable left roll. The aircraft struck a mountain at an altitude of 1,006 meters in conditions of low visibility and fog, which further prevented the crew from selecting a suitable emergency landing site.
Final Conclusions
The Interstate Aviation Committee (MAK) concluded that the crash was caused by the loss of lateral control due to the fire-induced degradation of the left wing's structural integrity and the failure of the aileron control system. Contributing factors included the inability of the fire suppression system to contain the blaze and the absence of clear operational guidelines for managing in-flight fuel leaks, which delayed critical crew actions. The investigation was completed within eight months of the accident.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
First Officer
Systems & Failure Modes
Ivchenko AI-20M Engines
Four turboprop engines; the number one engine suffered a fuel leak near the low-pressure pump that ignited on hot surfaces.
Fire Suppression System
The onboard system was unable to extinguish the fire in the engine nacelle once it had reached an advanced stage.
Aileron Control Wiring
Mechanical control rods for the left aileron were likely compromised by the fire, leading to a total loss of roll control.
Interesting Facts
- 01The aircraft was the oldest Russian-registered aircraft in commercial service at the time, manufactured in 1963.
- 02The debris field extended for approximately 5 kilometers in a forested, mountainous area.
- 03The aircraft was carrying 17.43 tonnes of cargo, including food, auto parts, and medicines.
- 04Search and rescue operations were significantly delayed by heavy fog in the Magadan region.
Safety Actions & Advisories
An-12 Fleet Suspension
Following the accident, Russian authorities temporarily banned the operation of Antonov An-12 aircraft until a comprehensive risk assessment program was completed.