Abstract: Employee #1 was welding on the rear end of a Hendrickson rig carrier, model 600-D-OH, serial #10832. The rig carrier was designed for a Hughes drilling rig, model LDH80, serial # 638. Employee #1 and a coworker were tack welding two pieces of metal in preparation for replacing the rig carrier's outrigger tube. To push the two pieces into position, the coworker used a Mustang front end loader, model 780, serial #21041, manufactured by Owatonna.. Once the pieces were tacked together, the coworker backed the front-end loader onto a slight incline, shut it off, and exited the cab without setting the parking brake. The coworker was engaged in other work when he saw the front end loader rolling toward Employee #1. The loader struck Employee #1, who was pinned against the rear of the drilling rig by the loader bucket. He sustained chest, back, and neck injuries, as well as a fractured right shoulder, internal injuries, numerous abrasions, and a chin avulsion.