What happened
On the morning of 25 September 2005, a wildfire broke out on a farm in Nylstroom, South Africa. Due to extremely dry vegetation and shifting winds, the fire spread rapidly. The pilot, who also owned the Robinson R44 Beta II (registration ZS-RTU), was using the helicopter to monitor the blaze and direct a ground-based firefighting team. Because there was no two-way radio communication between the aircraft and the ground crew, the pilot had to land periodically to exchange information with the team leader.
During one such landing attempt in an open field, the helicopter approached from the south, flying over a line of trees approximately 2.5 metres high. As the aircraft passed over the vegetation, the tail rotor struck the treetops. This impact caused the tail to swing violently, leading to a loss of control. The helicopter pitched forward and struck the ground on its left-hand side, with the main rotor also making contact with the earth. The force of the impact was severe enough to throw the pilot from his seat.
The investigation
An investigation by the SACAA AIID established that the aircraft was properly maintained by an approved organization and was airworthy at the time of the accident. The pilot held a valid private license and medical certificate. Investigators examined the wreckage and confirmed that the tail rotor gearbox had separated from the tail boom and that the tail rotor blades had failed following the impact with the trees.
Witnesses on the ground observed the sequence of events and noted that the engine was still running following the crash, requiring the team leader to manually cut the fuel mixture. The investigation also noted that the pilot had been using the helicopter earlier that morning to move a herd of buffalo to safety. While the pilot's son arrived quickly to assist in extracting the pilot from the wreckage using a vehicle, the pilot succumbed to his injuries in the hospital a few hours later. The final death toll was 1 fatality.
Findings
- The primary cause of the accident was that the pilot misjudged the height of the trees, leading to the tail rotor striking the branches.
- The lack of two-way communication between the aircraft and the ground crew necessitated frequent landings, which increased the pilot's workload.
- The impact forces during the crash sequence were too great to be survivable.