So it seems as though my issue with the two propellers is not limited to that model. I am having an issue exporting two animations (steering and brakeLight) on a car. When only the steering animation is used, it works fine. When both are used, neither works.
Also, in the car I am working on, I have a mysteriously appearing material called "1". No object contains this material and it only appears under the material tab when exporting. I have checked all objects, including collision boxes, and have insured that there are no mesh-less objects floating around. Any way to delete this material? Does it even matter if it is there?
It's gone now. Weird. There were some interestingly included UV Textures on some objects, so I guess deleting those got rid of the "1" material?