What happened
On 30 April 2001, a Robinson R22 Beta, registration ZS-HWG, was engaged in a game capturing operation near Farm Bondur in the Vivo/Messina district. The flight involved the pilot and a veterinary surgeon, who was tasked with darting buffalo from the air. After the initial takeoff from Farm Bondur, the pilot landed on a nearby farm road to allow the surgeon to disembark and treat a tranquilized animal.
Following the landing, the pilot took off once more to hover over the area, intending to guide the ground crew to the location of the animal. During this hover, the pilot heard a loud noise and observed an engine over-speed condition. In response to the mechanical failure, the pilot attempted an immediate autorotational landing, but the aircraft struck a tree during the maneuver.
The investigation
Investigators examined the mechanical state of the aircraft's drive system following the impact. The inquiry focused on the sequence of events leading to the engine over-speed and the subsequent loss of drive power. There were no fatalities or injuries resulting from the incident.
Findings
Technical analysis established that the accident was triggered by a foreign object entering the space between the forward V-belt and the pulley. This intrusion caused the belt to be displaced from its proper position, subsequently wedging it between the rear pulley and the belt. This chain of events resulted in both drive belts being forced off the pulley, leading to a complete failure of the drive system.