EE WAS WORKING TO REMOVE OLD STOPS IN PRIMARY JAW CRUSHER. JAW CRUSHER WAS OUT BEING REPAIRED.EE NEEDED TO GET OVER A BEAM IN ORDER TO STEP ON A SMALL PLATFORM TO DO HIS WORK. HE STEPPED ON THE BEAM WITH HIS LEFT FOOT. UPON RAISING HIS RT. FOOT OFF THE GROUND HE SLIPPED AND WENT HEAD FIRST IN THE OPENING CREATED BY THE MISSING JAW CRUSHER. EE FELL 13' TO THE CONCRETE BELOW.