What was found
INSPECTION TYPE:N/A LOSS OF CENTER HYD QTY & CENTER HYD PRESSURE. CREW DECLARED EMERGENCY. NOSE WHEEL STEERING WAS AVAILABLE AND TAXIIED TO GATE UNASSISTED. VERIFIED HYD LEAK AT NR 9 SPOILER ACT HOUSING CAP. FOUND O-RING UNDER CAP FLAT AND BROKEN, REF IPC 27-61-02 FIG 51. REPLACED O-RING. LEAK CHECK OK OF SPOILER. SERVICED CENTER HYD SYSTEM TO FULL. ON ARRIVAL A/C HYD WAS AT 20 PERCENT.