DISMANTLING A SCOOP CHARGER STATION, HE STOOD ON TOP OF THE CHARGER TO REMOVE FIREPROOF CLOTH FROM THE ROOF AND RIB. FOCUSING ON THE OVERHEAD WORK, HE STEPPED OFF THE EDGE OF THE CHARGER CATCH ING HIS LEFT FOOT BETWEEN THE CHARGER & THE RAP-ARROW PROTECTIVE PIPE CAUSING HIM TO FALL BACKWARD OFF THE CHARGER.