As the aircraft touched down, the pilot felt the left maingear leg give way. He applied power, but the aircraft did not climb away and the pilot was unable to maintain directional control. To avoid colliding with trees outside the airfield boundary the pilot closed the throttle and landed the aircraft. The left maingear leg collapsed and the right wing was damaged when it struck a small bush. An inspection of the landing gear revealed that the aircraft had suffered a heavy landing. It was also found that the nut on the gear upper retaining bolt had been stripped. This nut was not the type specified by the Glasair Construction Manual.