What was found
(CAN) ACFT WAS TAXING TO LINE UP FOR TAKEOFF. FLIGHT CREW NOTICED THAT HYDRAULIC NR 2 SYSTEM DROPPED FROM 70 TO 50 PERCENT. THEY CONTINUED TAXING AND THE HYDRAULIC FLUID DROPPED TO 45 PERCENT. FLIGHT CREW RETURNED TO THE GATE. THE HYD LEAK WAS CONFIRMED COMING FROM THE NOSE WHEEL WELL. MAINTENANCE ACTION MAINTENANCE INSPECTED THE ACFT AND FOUND THE SWIVEL FITTING BACKED OFF 180 DEGREES WHICH CAUSED THE HYD LEAK. MAINTENANCE SENT THE INFORMATION TO MFG AND REQUESTED A REV OF THE SWIVEL FITTING, SAFETY DEVICE.