Accident to the Dyn'aero MCR01 ULC identified 21ABU on 24/02/2018 at Trignac (Loire-Atlantique)

The pilot took off at 14:34 from Saint-Nazaire Montoir aerodrome (Loire-Atlantique) to conduct circuit patterns in the MCR01 ULC, which he co-owned. The first aerodrome circuit was completed without incident. At 14:51, at the end of his second circuit, the pilot announced that he was on final to runway 07. The controller cleared the pilot to land after receiving confirmation from the pilot that he would be doing a full-stop landing. Thirty seconds later, the pilot radioed in "Fox Uniform Papa, in danger", his radio continued broadcasting, and he then repeated "MAYDAY" three times. A witness onboard an aircraft at the holding point saw the MCR01 turning with a very steep bank angle at an estimated height of 50 m. The aircraft collided with the ground.

An asymmetrical flap extension on final made the microlight difficult or even impossible to control. The low height did not give the pilot enough time to regain control of the aircraft before hitting the ground.

The asymmetrical flap extension was likely caused by fatigue failure resulting from the alternating torsional forces exerted on a component part of the flap control universal joint on the left side of the aircraft. These torsional forces were created by abnormal contact between internal parts in the universal joint, which may have been exacerbated by a lack of lubrication. The lack of aircraft maintenance documentation, particularly between 2007 and 2013, meant that it was not possible to determine whether the lack of lubrication may have been due to a maintenance shortcoming or mismanagement of the storage of the aircraft.