I needed to put the propeller action under the other armature in the NLA editor.
I followed a tutorial here: https://youtu.be/0FIEzAlnVvw to rotate the propeller. I was able to do it on the first sub. But when I tried to make a second sub animate its propeller, it only rotates once. Also, in the NLA editor, when I add the action for the second (female) sub propeller, the location and rotation of that sub gets messed up. Can someone tell me how I can get the second sub’s propeller to rotate 360 degrees for the whole animation.
Note: the tutorial doesn’t show how to add a second sub, etc. I tried to do that on my own. So that’s why the NLA list of actions is not well organized.
Blend file: http://www.pasteall.org/blend/37434