What was found
A SYSTEM HYDRAULIC PRESSURE WENT TO ZERO IN FLIGHT. A SYSTEM LOW PRESSURE LIGHT ILLUMINATED. PERFORMED EMERGENCY PROCEDURES, HAND CRANKED GEAR DOWN. CLOSED HYDRAULIC FLUID SHUTOFF VALVES, USED ALTERNATE FLAPS AND SHUT OFF ALL A-SYSTEM COMPONENTS. TOWED BACK INTO THE PARKING AREA. FOUND NR 13 SPOILER ACTUATOR HAD A CUT ON RING. REPLACED SAME, LEAK AND OPERATIONAL CHECKED GOOD.