Accident Overview
On 21 November 2016, a Robinson R22 Beta II helicopter, registration ZS-RPT, was involved in an accident during a private game darting exercise near Sterkfontein Farm, approximately 34.2 nautical miles southeast of Welkom in the Free State Province. The aircraft was operated under Part 91 of the South African Civil Aviation Regulations. The pilot, aged 24, held a Commercial Pilot License (CPL) and had accumulated 264.5 total flying hours, including 226.3 hours on the Robinson R22 type. A veterinarian was on board as a passenger, equipped with a darting gun to tranquilize blue wildebeest that were to be relocated within the farm.
Flight Details
Both aircraft doors had been removed prior to the flight to facilitate the darting operation. The pilot reported that approximately 22 liters of fuel were on board at the start of the flight. The weather at the time was clear, with wind from 320 degrees at 11 knots, temperature 20°C, visibility 10 kilometers, and no significant cloud cover.
Sequence of Events
The pilot stated that after successfully darting an animal, he executed a right turn to confirm the hit. During this turn, the low main rotor RPM audible warning sounded. The pilot attempted to recover by initiating an autorotation, but was unsuccessful due to the helicopter's low altitude. The left skid made contact with the ground, digging in and becoming stuck, leading to a dynamic rollover. The helicopter rolled onto its side and sustained extensive damage.
Injuries and Damage
Neither the pilot nor the passenger sustained injuries. The helicopter, a Robinson R22 Beta II, was extensively damaged in the accident.
Investigation Findings
The investigation revealed that the accident resulted from a decay in main rotor RPM, which led to a loss of height and a hard landing on the left skid, followed by a dynamic rollover. The pilot was appropriately rated and licensed for the operation being conducted. The aircraft was being flown at low altitude to facilitate effective game darting. The low main rotor RPM warning activated during the right turn, and the subsequent autorotation attempt was unsuccessful due to insufficient height. The hard landing on the left skid initiated the dynamic rollover.
Probable Cause
The probable cause of the accident was a hard landing following a decay in main rotor RPM at a low height, resulting in a dynamic rollover.