As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER PUSHBACK/ENGINE START, PARK BRAKE WOULD NOT RELEASE. MAINTENANCE REPLACED THE PARK BRAKE VALVE, THE SYSTEM TESTED SERVICEABLE AND THE AIRCRAFT WAS SUBSEQUENTLY RELEASED FOR SERVICE. THE VALVE HAD BEEN IN SERVICE FOR 6205H/5700C SINCE THE LAST SHOP VISIT. (TC# 20190529001)