It seems to work better if you unparent the entity *before* calling Obj_Add(). Was there some particular reason you weren't doing that?
There wasn't any reason in particular that I can think of off hand (so many work arounds through the whole design of this editor that its hard to remember why you do certain things the way you did).
So it fixed the -45 degree offset (Y) on the propellar. Thats a start :-)
As you can see, it is getting frustrating.. It can't just be a 3ds thing, because if I load the mesh in straight and do no modifications to it (the 3ds file) everything will look correct in blitz. This means that blitz is returning incorrect values for rotation, or something...
Thanks for your help though Rottbott, its always nice to have a second set of eyes looking at something to prove that I am still in the relm of sanity!