Moving parts when attached to a rotation joint

[rifleman25]

I built a small jet with rotating wing and small jet engine fixed to a joint but even when i dont use the rotation joint the piece move from their position and the plane becomes unbalanced, i found that even respawning does'nt fix it, you have to go to a base and re-load the plane.
it didnt mater if the parts were alone or if i use multiples and slide them into oneother