As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT ON RETURN FLIGHT TO CLT CREW RECEIVED MAIN BRAKE FAIL CAS MESSAGE. CREW DECLARED AN EMERGENCY, USED LONGEST RUNWAY TO LAND, STOPPED ON RUNWAY AND USED TUG TO RAMP. MTN TROUBLESHOOTING FOUND THIS AS CAUSED BY AN INTERMITTENT QUANTITY SENSOR IN THE HYDRAULIC RESERVOIR. MTN REMOVED AND REPLACED RESERVOIR/SENSOR ASSY WITH SERVICEABLE UNIT. OPS CHECKS GOOD.