WORKER WAS PUTTING THE LEFT FRONT FENDER ON A 980-G CAT LOADER. HE PROCEEDED TO CLIMB DOWN FORM THE FENDER ON THE INSIDE OF THE TIRE AND CAUGHT HIS RIGHT FOOT BETWEEN THE TIRE & THE LOADER FRAME. HE LOST HIS FOOTING AND TURNED SIDEWAYS KNOCKING HIS HARD HAT OFF AND FELL HEAD FIRST INTO THE CORNER OF THE BACK OF THE LOADER BUCKET PUTTING A CUT ON TOP OF HIS HEAD.