25 October 1956 – A Bell XV-3s, (Convertiplane) crashes when pilot Dick Stansbury blacks out due to extremely high cockpit vibrations that occurred when the rotor shafts are moved 17 degrees forward from vertical. He is seriously injured and the airframe is damaged beyond repair.
In 1951, the Army and Air Force announced the Convertible Aircraft Program and released the Request for Proposals (RFP) to solicit designs from the aircraft industry. In October 1953, Bell Helicopter was awarded a development contract to produce two aircraft for testing purposes.
The Bell XV-3 (Bell 200) was an American tiltrotor aircraft developed by Bell Helicopter for a joint research program between the United States Air Force and the United States Army in order to explore convertiplane technologies.