Investigation Summary
The accident was a classic example of a 'wrong engine shutdown' scenario, exacerbated by poor flight deck ergonomics and maintenance failures. The initial failure of the left engine was caused by the disintegration of the 2nd and 3rd compressor stages, a result of vibration-induced loosening of nuts on the engine mounts. Investigation revealed the engine had been operated for over 30 hours with an unrepaired defect, including 38 missing screws on the main compressor. During the emergency, the flight engineer's ability to monitor engine parameters was hindered by weak illumination and the layout of the Tu-134B cockpit. Because the co-pilot (the pilot flying) had already neutralized the aircraft's bank, the captain did not feel the expected physical cues of a left-side failure and relied entirely on the flight engineer's incorrect report.
Final Conclusions
The investigation concluded that the primary cause was the crew's inadvertent shutdown of the serviceable number 2 engine following a mechanical failure of the number 1 engine. Contributing factors included poor crew coordination (CRM), inadequate flight deck ergonomics that made engine monitoring difficult in low light, and systemic maintenance failures that allowed the aircraft to fly with known, unrepaired engine defects.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Eduard Hasanov
First Officer
Sergey Kuliyev
Flight Engineer
Alexander Sokolov
Systems & Failure Modes
Soloviev D-30 Turbofan
The left engine suffered a mechanical failure due to vibration and missing mounting hardware, leading to compressor disintegration.
Flight Engineer Station
The ergonomics of the Tu-134B-3 cockpit made it difficult for the engineer to accurately monitor engine parameters in low-light conditions.
Interesting Facts
- 01The number 1 engine failed due to the disintegration of the 2nd and 3rd compressor stages.
- 02Maintenance records showed 38 screws were missing on the main compressor of the failed engine.
- 03The aircraft had been operated for 30 flight hours with a known, unrepaired defect prior to the crash.
- 04The flight engineer's error was attributed to poor cockpit ergonomics and weak illumination of engine instruments.
- 05The captain was deprived of sensory cues regarding which engine failed because the co-pilot had already corrected the yaw/bank.
Safety Actions & Advisories
Maintenance Oversight
The investigation highlighted the danger of using defective spare parts and operating aircraft with known mechanical issues, leading to stricter oversight of engine repair standards.
Cockpit Ergonomics and Lighting
The investigation identified that weak illumination at the flight engineer's station contributed to the misidentification of the failed engine, leading to recommendations for improved cockpit lighting and instrument visibility in Tu-134 aircraft.
Known Controversies & Unanswered Questions
Defective Spare Parts Allegations
Reference ↗Azerbaijan Airlines officials alleged that the engine failure was caused by defective spare parts, the use of which they claimed was permitted by the Russian engine manufacturer, Perm Motors.