AE isn’t a true 3D world so even if you could import the 3D scene you couldn’t just fly around it. You could possibly export 3D models out of the CAD program and then use a 3D plug-in for after effects like 3d invigorator(?) to insert the models in the After effects world. I’ve never used invigorator (or the other one I can’t remember the name) so I’m not so sure how much control you’d have, especially with textures and such.
I’d see if it is possible to animate a camera within the CAD program…..or see if you can export the CAD models into another 3D program like Cinema4D.
I have not really done anything like that, so hopefully someone else can give you a better response