What happened
On 6 April 2018, a pilot was conducting a check flight in an amateur-built 85ALT gyroplane at the Flavacourt microlight platform in France. The flight was intended to test the aircraft following the installation of a new cockpit canopy and modifications to the tail assembly.
As the aircraft lifted off from the unpaved runway, it immediately experienced a significant rightward yaw. Despite the pilot applying left rudder, the aircraft continued to climb while banking progressively to the right. During the climb, the gyroplane suddenly rolled to the left and onto its back, impacting the ground approximately 300 meters from the runway threshold. The impact resulted in one fatality and the total destruction of the aircraft.
The investigation
The BEA examined the wreckage and analyzed video footage of the accident. The investigation confirmed that the engine was producing continuous power until the moment of loss of control and that there were no mechanical failures in the control linkages.
Investigators reviewed the aircraft's history, noting that the pilot had performed several modifications to address previous handling issues, including adjusting the rotor's longitudinal and lateral positions to manage the center of gravity and engine effects. The investigation also focused on the recent addition of a cockpit canopy, which enclosed the cockpit with aluminum posts and a metal roof. Witnesses and experts noted that such enclosures can significantly alter the aerodynamic behavior of a gyroplane, specifically affecting yaw control.
Findings
Several factors contributed to the accident. The aircraft likely suffered from an aft center of gravity, which required the pilot to maintain a heavy nose-down input during takeoff. Additionally, the use of a heavier BMW engine, which rotates in the opposite direction of standard Rotax engines, had already made yaw control difficult.
The installation of the cockpit canopy was the critical factor, as it caused a significant deterioration in the aircraft's yaw stability. During the takeoff roll, the rudder lacked sufficient authority to counteract the engine's effects, leading to the uncontrollable rightward veer and subsequent roll.