What was found
BWI - FLT 2605, ON FINAL APPROACH, AFTER LANDING GEAR AND FLAPS WERE EXTENDED, THE 'A' SYSTEM HYDRAULIC QUANTITY DEPLETED TO ZERO WITH THE LOW PRESSURE LIGHT ILLUMINATING. FLIGHT LANDED WITHOUT INCIDENT AND TAXIED CLEAR OF THE RUNWAY. THE AIRCRAFT WAS TOWED TO THE GATE AND THE PASSENGERS DEPLANED NORMALLY. MAINTENANCE REMOVED AND REPLACED THE 'A' SYSTEM ELEVATOR PCU AND RIGGED PER MM 27-31-101A. (M) OPERATIONAL CHECK AND LEAK CHECK NORMAL. (M)