As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - RUDDER TRIM SWITCH FAILED, WOULD TRIM TO THE RIGHT BUT NOT TO THE LEFT. ON FINAL APPROACH, RUNAWAY TRIM FULL RIGHT RUDDER. ACCOMPLISHED A UNEVENTFUL LANDING. MAINTENANCE REPLACED THE TRIM PANEL, SWITCH INOP. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.