The Lower Right Landing Gear Weldment Failed On Landing Due To Fatigue Cracking Analysis: After landing, the pilot felt a violent tailwheel shimmy and the airplane veered left. He applied full right rudder and brakes, but the airplane continued to veer toward the left edge of the runway. The right main landing gear collapsed, followed by the left main landing gear, and the airplane departed the runway onto the grass. Postaccident examination found that both of the lower main landing gear weldments had fractured, in addition to the tailwheel attachment link.