What happened
On 24 January 2007, a Bell 206 L4 (registration ZS-RTR) was conducting a private flight from a refueling camp in Sudan toward a base camp. After replenishing the aircraft's fuel supply, the pilot reattached an under-sling load consisting of roughly 400 kg of cabling.
During the initial climb, the pilot maintained a steady power setting, reducing torque from 80% to 60% as the aircraft reached an indicated airspeed of 60 kts. While flying in favorable weather conditions, the pilot suddenly heard an audible bang, followed by a physical jerk and a yawing motion. This was immediately accompanied by a low rotor RPM warning.
Recognically facing an emergency, the pilot released the underslung cargo and transitioned into an autorotation. While flying approximately 300 feet above a treeline, the pilot maneuvered the aircraft toward an open field to land into the wind. The helicopter touched down on the rear section of the skids with no forward velocity, causing the main rotor blades to strike the vertical stabilizers. The pilot was uninjured during the event.
The investigation
Investigators examined the aircraft and the circumstances surrounding the mechanical failure. The inspection of ZS-RTR revealed damage to the engine, the engine cowling, and the vertical stabilizers. Physical evidence suggested that the engine had undergone an uncontained engine failure.
Records indicated that the most recent mandatory periodic inspection (MPI) had been completed on 05 January 2007, with the airframe having flown 90.0 hours since that service. The investigation noted that the incident occurred at an altitude of approximately 300 feet above nearby trees during the emergency descent.