As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED THE LT BUS TIE CIRCUIT BREAKER TRIPPED DURING THE PREFLIGHT CHECKS. TROUBLESHOOTING FOUND THAT THE LEFT BUS TIE RCCB P/N 45AS88810-003 S/N 001194 TO BE DEFECTIVE. INSTALLED A NEW RCCB, FUNCTIONAL CHECKS SATISFACTORY (RCCB = REMOTE CONTROLLED CIRCUIT BREAKER).