An employee was moving a pipe on a transporter. He was positioned backwards, and his foot went into a 0.5- to 1-inch access opening that connects transporters together. There were screws missing from the access hatch, which moved the access plate and caused the employee to fall over the side of the transporter from a height of 4 feet, 4.5 inches to the ground. The employee landed on a board, breaking a leg and a rib on his right side.