As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON LANDING, 2 ROTATING DISKS OF NR 4 BRAKE ASSEMBLY HAVE DISINTEGRATED INTO FRAGMENTS. MAINTENANCE PERSONEL REPLACED THE ASSY TO CORRECT THE SITUATION AND REPLACED THE BRAKE CONTROL VALVES AND THE AFFECTED WHEEL ASSY AS PREVENTIVE MAINTENANCE.