20000622014219A

(-23) During landing roll out pilot reported a severe tail wheel shimmy followed by the a/c drifting to the right, full left rudder was applied with no effects. A/c rotated clockwise and skidded off the right side of rwy 18SQUIGGILY skid marks from the tail wheel were observed on the rwy. Two pieces of the left rudder horn to tail wheel steering horn spring assembly was found in the grass along the initial rollout area. The clip portion had been pulled opened, allowing the spring to become disconnected, resulting in a loss of left steering control of the tail wheel. The left main gear collapsed and folded under the a/c when it struck a ditch in the grass area adjacent to rwy, the left wing struck the ground resulting in the wing tip and wing spar damage. There were no injuries. The PIC has 375 hours in various tail wheel a/c. (.4)according to the CFI who was occupying the right seat, they had been practicing both three-point and wheel landings. He said that this particular landing was a three-point landing. He said that when they touched down, the tail-wheel shook excessively back and forth at first and then it was smooth. He stated that the airplane veered right while both of them were pushing on the left rudder. The airplane departed the right side of the runway turned around about 180 degrees, slid left into a ditch and collapsed the left main landing gear. According to the CFI, and FAA inspector, a tail-wheel spring and associated parts had pulled apart from the tail-wheel and were later found on the runway near the point where the airplane veered right, off of the runway.