On June 22, 2003, about 1215 eastern daylight time, a Waco ARE, N20953, piloted by a private pilot, sustained substantial damage on impact with runway 23 during a landing roll at W K Kellogg Airport (BTL), near Battle Creek, Michigan. The personal flight was operating under 14 CFR Part 91. No flight plan was on file. Visual meteorological conditions prevailed at the time of the accident. The pilot reported no injuries. The flight originated in St Louis, Missouri at 0915 and was landing at BTL at the time of the accident. The pilot reported: Weather was clear with winds variable at 5 kts; not a factor. ... Landing touchdown was smooth, normal, on centerline. Landed on the mains with the tail down slightly, aircraft tracked straight. As aircraft continued to slow, the tailwheel was lowered onto the ground. Ground roll continued, aircraft came to the left a bit, inputted a little right rudder to correct. At this point, there was a sudden and strong learch forward. Aircraft quickly came to a stop on the runway, near centerline. Aircraft came to rest in pitched down, left wing low attitude with the left lower wingtip on the ground. ... Upon walking around the airplane, found the left main gear had collapsed and swung completely under the forward fuselage and rested against the right main gear. A Federal Aviation Administration Inspector examined the airplane. The inspector stated: Further inspection of the landing gear cross supports did not show any apparent pre-existing conditions to cause failure. The metal evident in the exposed crack areas did not have any signs of rust. Subsequent to the accident, the pilot determined that the cross support material used in the landing gear structure was not in accordance with the original design specifications. The original drawings on file at the Smithsonian Institute showed that the original wall thickness was greater than the failed material. The pilot stated that the airplane was repaired using the wall thickness specified in the original drawings.