What happened
Shortly after departing, the flight was in the initial climb phase when the crew encountered a sudden mechanical failure. While ascending through an altitude of 600 feet, a loud bang was heard from the airframe. Immediately following the noise, the aircraft began to shutter, and the fire warning light for engine number three illuminated on the cockpit panel.
In response to the warning, the crew discharged the first fire suppression bottle. However, the co-pilot visually confirmed that flames were still emanating from the affected engine, and the warning light remained active. Consequently, a second fire bottle was discharged to suppress the fire further. With the situation stabilized, the aircrew decided to return to the airport of departure. The aircraft landed without any further incident. Emergency response teams were already standing by on the ground, and all passengers deplaned normally.
The investigation
A thorough examination of the affected engine was conducted after the safe landing. The inspection revealed that the seventh-stage turbine assembly had suffered a catastrophic failure. This failure caused the component to penetrate the right side of the engine case. The displacement of the seventh-stage assembly resulted in collateral damage to the adjacent sixth and eighth stages. Additionally, the incident caused damage to nearby fuel lines and the fire warning system wiring.
Findings
The mechanical evidence points to a structural failure within the turbine section as the primary event. The subsequent fire was likely caused by the breach of the engine case and the ignition of leaking fluids or hot components. The crew's prompt response in discharging the fire bottles and returning to the airport prevented any escalation of the emergency.