Le lundi 22 juillet 2019 13:22:57 UTC+2, a écritÂ*:
It may be as simple as your fiberglass seat back rubbing against some part of the fuselage interior. Can you duplicate the sound while sitting in the cockpit on the ground?

I don't think it is the seat back, no sound while sittin in the cockpit on the ground. Maybe I will try with somebody else moving /shaking the wingtip while sitting on the ground to check if I can hear that noise...