Investigation Summary
The disaster began two minutes after takeoff when the first-stage low-pressure compressor disk of the starboard (No. 3) engine disintegrated. Shrapnel from the uncontained failure severed fuel lines and ignited a fire. In the high-stress environment, the flight engineer mistakenly shut down the healthy No. 2 (center) engine instead of the failing No. 3 engine. Although he realized the error ten seconds later and attempted a restart, the fire had already spread to the rear compartment, damaging the auxiliary power unit (APU) and the No. 2 engine's pylon. A critical malfunction then occurred where the No. 2 engine accelerated to takeoff power spontaneously, and while the crew managed to shut it down, the fuel valve remained open, feeding the inferno. The fire eventually caused a total failure of the aircraft's hydraulic systems, rendering the flight controls useless during the final approach.
Final Conclusions
The primary cause was a metallurgical and manufacturing defect in the low-pressure compressor disk of the Kuznetsov NK-8-2U engine. Contributing factors included the flight engineer's initial error in shutting down the wrong engine and the rapid spread of fire which led to a catastrophic loss of hydraulic pressure and electrical voltage, making a safe landing impossible.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Low Pressure Compressor Disk
A manufacturing defect in this component of the No. 3 engine led to the initial uncontained failure.
Hydraulic System
Fire damage to the rear of the aircraft caused a total loss of hydraulic fluid, removing the crew's ability to move flight control surfaces.
Engine Fuel Valve
The fuel valve for the No. 2 engine remained open despite the engine being shut down, continuing to feed the fire.
Interesting Facts
- 01The aircraft was five years old, having entered service in 1979.
- 02The only survivor was a 27-year-old male passenger who was seriously injured.
- 03The fire lasted approximately four minutes and 30 seconds before the final impact.
- 04The No. 2 engine spontaneously accelerated to takeoff speed due to fire damage to its control cables.
- 05Weather was clear with -18°C temperatures and did not contribute to the accident.
Safety Actions & Advisories
Compressor Disk Inspection
Following the investigation, mandatory inspections and stricter quality control measures were implemented for the manufacturing of NK-8 engine compressor disks.