What was found
(CAN) DISPATCH REPORTED A FLIGHT INCIDENT THAT ON LANDING THE RT OUTBOARD BRAKE SHATTERED. ON TAXI IN TO GATE THE RT INBOARD BRAKE OVERHEATED. MAINTENANCE FOUND THE NR 4 BRAKE SHATTERED WITH SIGNIFICANT DAMAGE TO THE PISTONS AND LARGE SECTIONS OF A ROTOR AND PRESSURE PLATE COMPLETELY MISSING. THE NR 4 BRAKE ASSEMBLY WAS REPLACED ALONG WITH THE NR 4 MAIN WHEEL ASSEMBLY. BOTH ARE BEING HELD FOR INVESTIGATION. THE NR 3 BRAKE ASSEMBLY WAS ALSO REPLACED AS A PRECAUTION. IT WAS OVERHEATED BUT WAS OTHERWISE SERVICEABLE. AIRCRAFT WAS RETURNED TO SERVICE. NO OTHER DAMAGE NOTED.