No. Rotating fan blades sound like a classical detail overkill... that's a lot of polygons to be rendered for very little gain.
It is possible, of course, just look at how animations work. The fan will have to be a seperate mesh group, since Orbiter doesn't support vertex animations. Then you just set up a rotation for that mesh group, and slave the rotation speed to the engine thrust.
As for the idle engine sound when on zero thrust, you should be able to make it a looping sound that kicks in when the engines are running, completely detached from your thrust setting. Allthough you'll probably want to cut it when thrust rises above a certain level.