What happened
On 5 September 2013, a private AutoGyro Calidus (registration ZU-RHE) was performing a take-off from runway 31 at Baragwanath Airfield in Gauteng. The pilot, the sole occupant of the aircraft, intended to conduct a series of circuits and landings. During the initial take-off roll, the pilot maintained the control column in a forward position while the rotor reached 200 rpm. As the pilot applied additional power to lift off, he abruptly pulled the control column fully back. This sudden maneuver caused the aircraft to lift slightly before rolling to the left. The rotor blades struck the ground, causing the aircraft to come to rest on its right side. While the impact caused extensive damage to the propeller, rotor, nose section, and main landing gear, the pilot escaped without injury.
The investigation
SACAA AIID investigators examined the aircraft's mechanical condition and the pilot's flight history. Post-accident inspections of the engine, including a shock load test and turbo control unit (TCU) data downloads, confirmed the powerplant was functioning normally and was producing power at the time of impact. The aircraft's weight and balance were within limits, and the maintenance records showed the aircraft was properly equipped and maintained. The investigation also reviewed the pilot's experience, noting that while the pilot was a licensed national pilot, he had only accumulated 9.4 hours on this specific aircraft type over the preceding months, with significant gaps in recent flight activity.
Findings
- The primary cause of the accident was the loss of lateral control during the take-off phase.
- The pilot's technique contributed to the incident; by holding the control column forward for an extended period while the rotor was at a specific speed, the rotor disc became unloaded.
- This lack of loading allowed for high-speed rotor blade flapping. When the pilot suddenly pulled back on the stick, the leading blade encountered high resistance and flapped, causing the aircraft to roll.
- The pilot's understanding of the specific operational procedures for this aircraft model was found to be inadequate.
- The aircraft's rotor system was subjected to excessive forces that led to the blades striking the ground.