What was found
DURING TAKEOFF, THE PIC REPORTED A BUFFERING IN THE LEFT BRAKE JUST PRIOR TO TAKEOFF. DURING LANDING, THE PIC REPORTED A SIGNIFICANT DIFFERENCE IN BRAKING AUTHORITY BETWEEN THE RIGHT AND LEFT SIDE WHICH RESULTED IN THE AIRCRAFT DEPARTING THE RUNWAY INTO THE DIRT. IT WAS IDENTIFIED THAT THE LEFT WHEEL BEARING, RETAINING NUT, AND COTTER PIN HAD SEPARATED FROM THE AIRCRAFT FOR UNKNOWN REASONS. IT IS UNCLEAR WHETHER THIS WAS DUE TO A FAILED OR MISSING COTTER PIN.