What happened
On 29 July 2021, a private local flight ended in a fatal accident at the Fousseret microlight strip in Haute-Garonne. The pilot, operating a 31RS flex-wing microlight, performed a standard takeoff from runway 10. After an initial climb to approximately 45 meters, the aircraft began a steady descent while remaining on the runway axis. Shortly before impact, the wing structure suddenly deformed and folded, causing the trike to oscillate violently. The pilot lost control, and the aircraft struck the ground approximately 17 and 170 meters beyond the runway end, resulting in one fatality and the destruction of the microlight.
The investigation
The BEA examined the wreckage and analyzed video footage from a camera mounted on the wing. The investigation focused on the state of the ORYX 14 wing's tautening system, which uses a metal cable, hook, and ball pin to maintain the wing's shape. Investigators found that while the components themselves were undamaged, the hook was not properly seated in the rear hanger, and the ball pin was only partially inserted in a position that failed to secure the system.
Evidence from the flight's video recording showed that the engine power remained constant during the descent, but the wing's leading edges deformed due to aerodynamic forces. The investigation also reviewed maintenance records, noting that the pilot had replaced a batten on the right wing a few days prior to the accident. This maintenance required slackening the wing via the tautening system.
Findings
- The primary cause of the accident was the improper securing of the wing's tautening system following maintenance.
- The pilot had slackened the wing to replace a batten and likely failed to correctly reposition the hook and ball pin to the required setting.
- The aerodynamic forces encountered during the climb caused the unsecure wing to partially fold, leading to an immediate loss of lift and control.
- A visual inspection of the tautening mechanism was likely hindered by the height of the wing when installed on the trike, preventing the pilot from detecting the error.