Cat. 2 investigation report: simplified-format report, adapted to the circumstances of the occurrence and the investigation stakes.
In the months leading up to the accident flight, the pilot modified his microlight’s engine intake system. The day before the day of the accident, the pilot made an injection test flight lasting around 15 minutes after seven months without flying.
On the day of the accident, the pilot flew over several friends’ houses. The flight took place at a height of around 1,500 ft. During a turn-around towards the microlight strip, when the microlight was above the house of a friend, its pitch was significantly reduced whilst its speed increased, reaching close to the VNE.
The possible presence of play introduced on the elevator trim control linkage during the modification of the engine intake system by the pilot may have generated a flutter phenomenon on the RH elevator, causing flapping. Alternating forces rapidly increased until it ruptured mid-air. Integral with the stabilizer by its hinges, the elevator introduced an abnormal upward bending and torsional force on the stabilizer leading to the sudden rupture of its spar then to its complete separation mid-air.
With only half a horizontal tailplane remaining and a defective elevator, it is likely that the pilot was unable to keep control of his microlight, which continued to descend. The pilot deployed the reserve parachute at insufficient height and the microlight collided with the ground.