Investigation Summary
The flight was operating on behalf of Tomsk Avia when a magnetic chip detector light illuminated, indicating metal particles in the port engine oil. Despite this warning, the captain elected to continue toward the destination. Eight minutes later, a burning smell and a brief fire alarm occurred, yet the crew only throttled back the engine rather than shutting it down. It was only after oil pressure dropped to zero and severe vibrations began that the crew performed an emergency shutdown and activated the fire suppression system. By this time, the fire had spread beyond the reach of the extinguishers. With the engine still burning and the aircraft losing altitude, the crew attempted a ditching in the Ob River. The river's shallow depth and undulating bed caused the airframe to sustain massive structural damage upon impact, leading to the fatalities.
Final Conclusions
The Interstate Aviation Committee (MAK) concluded that the primary cause was an engine fire resulting from the failure of the No. 2 support bearing of the compressor rotor. This failure was attributed to either a manufacturing defect or improper reassembly during maintenance. A critical contributing factor was the crew's failure to shut down the engine immediately upon the first signs of fire, which allowed the fire to develop to a point where the onboard extinguishing system was ineffective. Furthermore, the West Siberian Transportation Prosecution Office found that required maintenance checks for the magnetic chip detector had been falsified in the technical logs.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Magnetic Chip Detector
A sensor in the engine oil system designed to attract and detect metal fragments, providing an early warning of internal component wear or failure.
Ivchenko AI-24 Turboprop
The aircraft's powerplants; the port engine suffered a catastrophic bearing failure leading to an uncontained fire.
Fire Suppression System
Onboard extinguishers designed to put out engine fires; the system failed to stop the blaze because the engine was not shut down promptly.
CA-24 Centrifugal Breather
A component of the engine venting system; its failure led to the release of an air-oil emulsion into the engine compartment, which then ignited.
Interesting Facts
- 01The aircraft was 36 years old at the time of the accident.
- 02Maintenance logs for the magnetic chip detector were found to have been falsified.
- 03The fire suppression system was unable to extinguish the fire because it had already spread too far.
- 04Seven passengers were killed; 19 people were treated for various injuries following the ditching.
- 05The captain's decision to continue the flight after the initial chip detector warning was cited as a contributing factor.
- 06The ditching occurred at a speed of 240 km/h, leading to the separation of the left-hand propeller and gearbox upon impact with an underwater obstacle.
Safety Actions & Advisories
Criminal Prosecution
Two officials from Angara Airlines were charged following the discovery of falsified maintenance records regarding the engine's magnetic chip detector.