Données issues du rapport préliminaire des autorités de la Belgique :
The pilot brought the helicopter to a hover, moved laterally towards the parking spot 2, then moved to the arking spot 3. Above parking spot 3, he wanted to position the helicopter into the wind and initiated a counter-clockwise rotation.
The pilot suddenly felt that the tail hit an obstacle, the helicopter turned to the right somewhat, then violently to the left, as the tail rotor failed.
The pilot reaction was to lower the collective controls and land immediately.