As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON SHORT FINAL INTO PDX, FULLY CONFIGURED, TR1 CIRCUIT BREAKER POPPED. AS A PRECAUTION, CAPTAIN REQUESTED TO HAVE THE EMERGENCY EQUIPMENT STANDING BY. AIRCRAFT LANDED AND TAXIED TO THE GATE WITHOUT INCIDENT. CONTRACT MAINTENANCE WAS CALLED TO EVALUATE PROBLEM. MAINTENANCE REMOVED AND REPLACED THE TR1. OPERATIONAL CHECK GOOD REFERENCING MM 24-21-31-4. BUS TRANSFERRED SEVERAL TIMES OK.