As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI OUT, THE RT BRAKE FAILED AND THE LT BRAKE REPORTEDLY LOCKED. DISCOVERED THAT THE RT MASTER CYLINDER HAD FAILED AND THAT THE LT BRAKE DID NOT LOCK UP AS IT WAS THE ONLY BRAKE WORKING. THE MASTER CYLINDER WAS REPLACED AND OPERATIONALLY CHECKED GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.