What was found
(CAN) DURING A ROUTINE WALK AROUND UPON ARRIVAL INTO YYC IT WAS NOTICED THAT THE NR 4 MAIN WHEEL DUST COVER WAS MISSING AND APPEARED TO HAVE SHEARED OFF THE RIM, THE OUTER WHEEL BEARING HAD DISINTEGRATED. IT WAS LATER DISCOVERED THAT THE INNER BEARING HAS ALSO DISINTEGRATED AND THE BRAKE ASSEMBLY WAS SEIZED ON THE RIM. WHEN WHEEL/BRAKE ASSEMBLY WAS REMOVED DAMAGE TO AFFECTED AXLE WAS FOUND TO BE BEYOND ALLOWABLE LIMITS. MAIN LANDING GEAR TRUCK ASSEMBLY WAS REPLACED AND AIRCRAFT WAS RETURNED TO SERVICE.