On June 30, 1996, at 1400 eastern daylight time, a Piper PA-20, N7685K was substantially damaged following a collision with terrain during landing rollout near Calhoun, Georgia. Neither the airline transport pilot, nor his passenger were injured in the accident. The aircraft was being operated under the provisions of Title 14 CFR Part 91 by the pilot. Visual meteorological conditions existed at the time, and no flight plan had been filed for the local, personal flight. The flight departed Calhoun, Georgia at 1300. The pilot stated that during landing roll, the tail wheel began to vibrate. The aircraft began to veer off the runway to the left, and he was unable to stop the turn with rudder. The aircraft ran off the side of the runway, and the left main landing gear and left wing were substantially damaged after contacting the rough terrain on the side of the runway.