As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON LANDING PILOT NOTED THAT LT BRAKE HAD FAILED. A/C RETURNED TO RAMP WITHOUT INCIDENT. MAINTENANCE DISCOVERED THAT THE BRAKE CALIPER PISTON HAD EXTENDED SO FAR THAT THE O-RING WAS COMPROMISED ALLOWING COMPLETE HYDRAULIC FLUID LOSS. BRAKE PADS AND DISC WERE WORN BEYOND LIMITS.