What happened
On 3 August 2016, a Robinson R44 Raven II, registration ZS-RXW, was conducting a private flight in the Lusikisiki area of the Eastern Cape. The mission was intended to assist a fixed-wing pilot whose aircraft had become grounded due to a flat tire at a private airstrip. The helicopter departed Margate Airport with the pilot and three passengers.
While traversing a ravine, the aircraft encountered intense atmospheric disturbances. Eyewitnesses observed the helicopter flying at a low altitude before it suddenly pitched nose-down. During this maneuver, the main rotor blades experienced significant upward movement, which severed the tail boom. The aircraft subsequently plummeted into the ravine, impacting a rocky surface with high force. All four occupants sustained fatal injuries.
The investigation
SACAA AIID investigators examined the aircraft's maintenance history, the meteorological conditions, and the flight's weight and balance. The investigation confirmed that the aircraft had been properly maintained and held a valid certificate of airworthiness. However, analysis of the flight's mass revealed that the helicopter was operating above its maximum allowable takeoff weight of 2500lbs, weighing approximately 2614lbs at departure.
Investigators also reviewed weather data, which indicated strong winds of approximately 20 knots and significant turbulence caused by air flowing through the ravine. The investigation focused on the interaction between the aircraft's rotor system and the pilot's response to the sudden downdraft.