EMPLOYEE WAS TIGHTENING TRACK PAD BOLTS ON THE HYDRAULIC SHOVEL. THE INCH DRIVE RATCHET WITH 3 FT PIPE SLIPPED CAUSING EE TO TWIST HIS BODY AND FALL DOWN AND BREAK HIS ANKLE, SNOW AND ICE WERE ON THE GROUND AT THE TIME. EE RECEIVED A NON- DISPLACED FRACTURE TO HIS LEFT ANKLE.