One of the priority causes of the Tu-154 plane crash now is the penetration of foreign objects in the engine, a law enforcement source told TASS on Dec. 27.
"One of the key versions of the crash at the moment is the penetration of foreign objects in the engine," the source said, adding that other possible causes such as pilot error and technical malfunction were also being considered.
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Russia’s Federal Security Service said on Dec. 26 that investigators were considering four main possible causes of the crash - penetration of foreign objects in the engine, substandard fuel that caused the loss of thrust, pilot error and technical malfunction of the plane.
According to the FSB’s latest conclusions, no evidence has been found linking the crash to terrorism.
A Tu-154 plane from Russia’s Defense Ministry crashed in the early morning hours of Dec. 25 shortly after taking off from the Black Sea resort of Sochi.
There were 92 people on board the aircraft, including eight crew members and 84 passengers that lost their lives in the plane disaster.