The pilot reported that, during the landing rollout, the left rudder pedal suddenly "went slack" and went forward to the firewall. He was unable to use the wheel brakes, and the tail slowly yawed to the left. The airplane skidded, the main landing gear failed, and the airplane came to a stop on the turf runway. An inspector with the Federal Aviation Administration inspected the wreckage and confirmed substantial damage to the left wing and fuselage. The pilot reported, and the FAA inspector confirmed, that the left rudder cable turnbuckle was found disconnected its safety wire was broken. The threads of the cable rod end were not stripped. The last annual inspection on the airframe occurred about five months prior to the accident.