What was found
FLT 4777 - DURING APPROACH INTO DFW FROM ORD, THE CREW RECEIVED A HYDRAULIC THREE LOW PRESSUER CAUTION LIGHT WHEN THE GEAR HANDLE WAS LOWERED, FOLLOWED BY A GEAR DISAGREE WARNING. THE NOSE GEAR INDICATED DOWN AND LOCKED WITH THE MAINS UNSAFE. THE AIRCRAFT PERFORMED A GO-AROUND AND THE QRH WAS COMPLIED WITH. THE NR 3 HYDRAULIC SYSTEM FLUID LEVEL WAS AT FIVE PERCENT AND THE PRESSURE INDICATED 100 PSI. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT LANDED SAFELY IN ORD. DURING SERVICING OF THE NR 3 HYDRAULIC SYSTEM, MAINTENANCE OBSERVED A LEAK FROM THE NR 3 HYDRAULIC RESERVOIR, REMOVED AND REPLACED IT. OPERATIONAL AND LEAK CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)