if i'm not wrong, another way to do that is to use the organizer to create nested groups.
for example, you can create a "rotor" group and a "helicopter" group containing both the fuselage and the "rotor" group.
now select the "rotor" group and create a behavior. animate the rotation and make the animation as long as the flight path requires.
now, using the organizer, select the helicopter group and add it to the same behavior created before.
animate the flight movement of the whole "helicopter" group and i think you're done 😄
just for my own curiosity, are you working for an helicopter company or is just for fun? 🙂