EMPLOYEE WAS USING A MANUAL HYDRAULIC PUMP TO ADJUST THE PARKING BRAKE ON AN END DUMP. WHILE PRESSURIZING THE SYSTEM, THE COVER PLATE BLEW APART AND HIT HIM ON HIS LEFT SHOULDER. THE DOCTOR RE STRICTED THE USE OF HIS LEFT ARM ON 10/4/02. ***HE WAS RELEASED BACK TO FULL DUTY ON 10/7/02.**