create a vector3 variable called DirectionOrig and then one called DirectionCur.
then use the transformDirection action in your FSM. Set the gameObject to your propellor gameObject. Set the direction value to your DirectionOrig and set the output vector3 to your DirectionCur. Check Every frame. Now use your Direction Cur in an addForce action with the target being your character and the space being world.
Now all you need to do is to set the Direction Orig to something that makes it point towards the axis the propellor should fly. Like, if it points up the vector3 would be 0,1,0. Make sure you check it in local/self space.
This makes it recalculate the direction from local space of the propellor into global space, which you can then globally(world) apply on any other gameObject. If the propellor rotates, the directionOrig will put out a different direction.
Do you want pics? It's actually quite simple once you've understood the principle of those transform actions. They can be a real pain in complex situations