Abstract: On August 30, 2005, Employee #1 was driving a Demag AC 1300 hydraulic truck crane, Serial Number 79047, backward into position at a multi-family unit construction site. The crane was traveling less than 0.5 miles per hour. A coworker was directing Employee #1 from outside the crane. The coworker noticed that the upper house superstructure (boom and jib) was moving; indicating that the house lock was not engaged. The coworker then climbed up onto the crane to try and stop the upper house superstructure from swinging in a forward motion, over the driver's side of the crane. The coworker reached into the cab and pulled the joystick control, and the swinging of the superstructure stopped. However, the crane was leaning toward the driver's side since the center of gravity changed. The crane then rolled onto its side. The coworker was thrown to the ground. The battery, which was located under the passenger seat, rolled onto Employee #1 and battery acid was spilled onto him. He suffered first- and second-degree burns to his lower back and buttocks area and was hospitalized at Western Medical Center in Santa Ana, CA for 10 days.