What was found
AT 10000 FT, RECEIVED NR 1 HYD ISOLATION VALVE AND ROLL SPOILER INBD HYD CAUTION MESSAGES. CREW STARTED NR 1 HYD ISOLATION VALVE QRH PROCEDURES AND AT THAT TIME HAD 15 PERCENT HYD QTY IN SYS 1. F/A VERIFIED FLUID LEAKING FROM ENGINE NACELLE. DECLARED AN EMERGENCY. 10 MILES FROM LANDING STILL HAD 5 -10 PERCENT OF QTY IN SYS 1. ON BASE LEG CAPTAIN CALLED FOR FLAPS 5 BUT RECEIVED A FLAP POWER WARNING AND ELECTED TO GO AROUND. RAN QRH AND ON NEXT LANDING ATTEMPT. LANDED WITHOUT INCIDENT, MX INSPECTED ACFT AND FOUND A DAMAGED O-RING ON THE HYD MANIFOLD. MX REPLACED BOTH THE O-RING AND CLAMP IAW AMM AND OPS CHECKED GOOD.