Employees were moving a 1,000-pound pallet of material toward the back of a box truck. One of them was using a hand truck, pushed under the front of the pallet, to help lift it; the hand truck slipped out and the employee fell off the back of the box truck. He landed on his head on the ground about 3 1/2 feet below, suffering a fracture to the left eye socket and a laceration in the same area.