What was found
PRIOR TO TOP OF DESCEND BOTH HYDRAULIC PUMPS OUTPUT PRESSURE ZERO. AILERON AND RUDDER REVERSION LIGHTS ON. COMPLETED EMERGENCY ABNORMAL HYDRAULIC CHECKLIST. CHECKED A/C FOR HYDRAULIC LEAK, NO LEAKS NOTED. INSPECTED MAIN HYDRAULIC CASE DRAIN FILTERS FOR CONTAMINATION, NO DEFECTS NOTED IN ACCORDANCE WITH DC8 MM 27-10-27 AND 29-10-17. CHECKED HYDRAULIC BYPASS LEVER FOR DETENT AND RIGGING PER MM 29-10-18, FOUND AIR IN HYDRAULIC SYSTEMS, BLED AIR FROM NR 2 ENGINE DRIVEN PUMP AND FLIGHT CONTROLS IN ACCORDANCE WITH MM 71-00 AND PERFORMED OPERATIONAL CHECK OF HYDRAULIC PUMPS PER MM 29-30-0; VERIFIED PROPER OPERATION OF INDICATION IAW MM 29-20-0; PUMPS OPERATIONAL CHECK GOOD.