This should be a cautionary tale for experienced and new drone pilots/owners (especially those of you who received a drone for Christmas!), "Drone collides with US Army helicopter, puts 1.5” dent in rotor".
As a reminder, any drone owner with a drone 0.55 lbs [or up to 50 lbs] is required by the FAA to register their drone. You can do so on this FAA link. The good news is if you've previously registered any drones, you can use the same UAS certificate number on any new drone purchases. Just add a label with your certificate number somewhere visible on your drone. Hope this info was helpful!