What was found
(CAN) FLIGHT CREW CALLED STATION TO REPORT THAT THEY LOST HYDRAULIC PRESSURE DURING TAXI TO THE GATE. MAINTENANCE AND TOW CREW CALLED FOR ASSISTANCE. MAINTENANCE HAD TO CAP THE NR 12 LINE AND THE ACFT WAS TOWED TO THE GATE. THE SPILL WAS 2 FT X 2 FT AND IT WAS CLEANED UP. CENTER HYDRAULIC FLUID LOW RF .39-.40. SHOWING VISUAL INDICATIONS SHOWED NR 12 WHEEL/BRAKE SMOKING . NR 12 WHEEL TEMP NORMAL. FOUND NR 12 BRAKE QUICK DISCONNECT BACKED OFF & LEAKING. RESECURED FITTING HYD SYSTEM, CTR, REFILLED & BRAKE OPERATION & LEAK CHECK CARRIED OUT. ALL NORMAL.