Investigation Summary
The investigation into Flight 7841 highlighted a critical failure in ground operations and pre-flight preparation, though it encountered evidentiary hurdles. The Tupolev Tu-134A had remained stationary at Minsk for seven days before the flight. While the lack of deicing was a primary suspicion, investigators noted that due to the significant damage to the airframe and engines, they were unable to definitively prove the exact point of ice accumulation or its origin. Just six seconds after liftoff, the left engine began surging and lost power. While the crew was attempting to return to the airport, the right engine also failed due to ice ingestion. The ingestion caused severe damage to the engine compressors and led to over-temperature conditions in the turbine sections. With no thrust available at a low altitude, the captain performed a forced landing into a forest. The aircraft's impact with 30-meter-tall trees caused it to break apart and catch fire, though the tail section remained relatively intact, allowing for 22 survivors.
Final Conclusions
The primary cause of the accident was the ingestion of ice into both engines during the takeoff climb, which resulted in compressor stalls and total engine failure. The ice had accumulated on the wings during a week-long period on the ground and was not removed because the aircraft was not deiced before the flight. The subsequent dual engine failure at low altitude left the crew with insufficient time and altitude to return to the runway.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Soloviev D-30 Engines
Both engines suffered catastrophic internal damage and flameout due to the ingestion of ice shed from the wings.
Deicing System
The ground deicing procedures were not utilized, allowing accumulated ice to remain on the airframe during takeoff.
Vibration Monitoring System
An excessive vibration alarm alerted the crew to the imminent failure of the right engine shortly before it lost power.
Interesting Facts
- 01The aircraft had been parked on the apron at Minsk for one week prior to the accident.
- 02No deicing was performed on the aircraft before the scheduled departure to Leningrad.
- 03The left engine failed just six seconds after liftoff at a speed of 325 km/h.
- 04The right engine failed 65 seconds after takeoff at an altitude of 240 meters.
- 05The investigation found that ice ingestion caused compressor stalls and turbine over-temperature in both engines.
- 06There were 22 survivors, including both the captain and the co-pilot.
Safety Actions & Advisories
Deicing Protocol Enforcement
The accident reinforced the necessity of strict adherence to airframe deicing protocols, especially for aircraft that have been stationary in freezing conditions for extended periods.