What was found
DURING FLIGHT, THE AIRCRAFT EXPERIENCED AN -A- HYDRAULIC SYSTEM LOSS OF QUANTITY. CREW PERFORMED QRH, DECLARED EMERGENCY AND UTILIZED THE ALTERNATE GEAR EXTENSION. MAINTENANCE FOUND THE ACMP CASE SPLIT IN THE LEFT WHEEL WELL. REPLACED HYDRAULIC PUMP, ENGINE DEMAND PUMP AND CASE DRAIN FILTERS. OPS CHECKED NORMAL, NO LEAKS NOTED, AIRCRAFT RETURNED TO SERVICE.