What happened
On 2ability 26 May 2018, an AutoGyro Calidus, registration ZU-RCA, was performing a private pleasure flight departing from Tedderfield Airpark in Gauteng Province. The aircraft, operated by the pilot for a scenic circuit, was beginning its takeoff roll on runway 29 when it suddenly experienced a violent roll to the left. The aircraft flipped onto its left side and skidded approximately 25 meters along the runway before coming to a halt on a nearby grassy area. Both the pilot and the passenger sustained minor injuries and required medical treatment at a hospital.
The investigation
An investigation by the SACAA AIID examined the mechanical and operational circumstances of the accident. The inquiry focused on the aerodynamic phenomenon known as high-speed blade flap. The investigation reviewed the aircraft's maintenance history, noting that the AutoGyro Calidus had 112.6 total flight hours and was within its valid airworthiness period. Meteorological data confirmed favorable flying conditions, with clear visibility and light winds, indicating that weather was not a contributing factor to the event.
Findings
The investigation established that the primary cause of the accident was a failure to properly manage the control stick during the initial takeoff phase. It was determined that the pilot applied throttle and released the brakes to build forward speed but failed to pull the control stick back in a timely manner. When the pilot eventually attempted to correct the position of the stick, the resulting torque—caused by the sudden lift imbalance between the advancing and retreating rotor blades—induced a high-speed blade flap. This aerodynamic imbalance forced the gyroplane onto its left side, leading to the subsequent rollover and substantial damage to the main rotor blades, propeller, canopy, and landing gear.