Investigation Summary
The flight was a multi-leg scheduled service from Khabarovsk to Leningrad. During the climb out of Sverdlovsk at an altitude of approximately 130 to 150 meters, the crew selected nominal thrust, which triggered a failure in the right-hand Mikulin AM-3M-500 engine. Metal fatigue cracks in a second-stage compressor blade had caused the blade to fail, leading to immediate and violent vibrations throughout the fuselage. These vibrations were so intense that the flight deck crew could not clearly see the engine instruments to determine which side had failed. In an attempt to diagnose the failure by sound and feel, a crew member moved the throttle of the healthy left engine, but mistakenly moved it into the shut-off position. With both engines now producing no thrust, the aircraft began a rapid descent. The crew steered toward the frozen Nizhneisetsky Pond for an emergency landing. The Tu-104 struck the ice at high speed and slid for 870 meters before reaching the shore, where it broke into three sections upon impact with trees and a building.
Final Conclusions
The investigation concluded that the primary cause was a double engine failure resulting from a combination of mechanical failure and crew error. The initial failure was caused by metal fatigue in the right engine's compressor. The total loss of power was attributed to the crew's inadvertent shutdown of the functioning left engine while attempting to identify the failed engine under conditions of extreme vibration that rendered cockpit instruments unreadable.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Mikulin AM-3M-500 Engines
The aircraft's powerplants; the right engine suffered a second-stage compressor blade failure due to metal fatigue.
Engine Throttles
Used by the crew to test engine response; improper manipulation led to the accidental shutdown of the remaining functional engine.
Interesting Facts
- 01The aircraft was only two years old at the time of the accident.
- 02The 7 fatalities comprised 5 occupants (3 passengers and 2 crew members) and 2 people on the ground.
- 03The fuselage broke into three distinct sections, but no fire broke out after the crash.
- 04The vibration was so severe that the crew was physically unable to read the engine status instruments.
Safety Actions & Advisories
Engine Failure Identification Procedures
The investigation highlighted the danger of attempting to identify a failed engine by manipulating throttles of healthy engines under high-stress, high-vibration conditions, reinforcing the need for strict adherence to instrument-based verification.
Instrument Readability Standards
The accident demonstrated that extreme airframe vibration could render cockpit instruments unreadable, leading to recommendations for improved vibration damping and instrument legibility in the Tu-104 series.