One May 12, 2001, at 1215 central daylight time, a Cessna 310 twin-engine airplane, N6748X, was substantially damaged during landing at the Decatur Municipal Airport near Decatur, Texas. The airplane was owned by a private individual and operated by Wise Aviation Services of Decatur, Texas. The flight instructor and commercial pilot receiving instruction were not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 instructional flight. The local flight originated from the Decatur Municipal Airport, at 1125. The flight departed the airport to the west to practice upper air work. Upon return to the airport, the commercial pilot receiving instruction entered the traffic pattern for runway 34. The flight instructor reported that the approach appeared to be "normal," and the airplane touched down on the centerline. After the main landing gear touched down, the airplane began to veer 20 degrees to the left. The instructor took control of the airplane and applied full right rudder; however, this had no effect. The instructor then applied full throttle and as the left main landing gear exited the runway, the airplane became airborne. The airplane then struck two runway signs, and the instructor reduced the throttles to idle and the mixture controls to the cut-off position. The airplane touched down in the grassy area between the runway and parallel taxiway collapsing the landing gear. The airplane slid about 400 yards and came to rest upright on the parallel taxiway. An examination of the airplane by the FAA inspector, who responded to the accident site, revealed that the left wing leading edge had a 3-foot tear. The left wing was bent up near the fuselage. The nose and left main landing gear were found collapsed, and the right main landing gear was found separated from the airplane. Examination of the runway revealed a single skid mark veering left to where the airplane exited the runway.