What was found
(CAN) DURING CLIMB THROUGH 10,000 FEET, THE NR 2 HYD QUANTITY GAUGE DECREASED, NR 2 HYD ISO VALVE CAUTION LIGHTS ILLUMINATED. AIRCRAFT ELECTED TO RETURN TO DEPARTURE AIRPORT, ALTERNATE GEAR EXTENSION SYSTEM USED. NORMAL LANDING. MAINTENANCE INSPECTION FOUND TUBE ASSEMBLY (ELBOW TO SOLENOID VALVE DOOR SEQUENCE OPEN) LEAKING. LINE REPLACED, HYDRAULIC FLUID REPLENISHED, GEAR SWINGS CARRIED OUT , AIRCRAFT RETURNED TO SERVICE.