As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - RUDDER TRIM DOES NOT ENGAGE, WHEN TURNING KNOB RIGHT KNOB IS TURNED WELL PAST THE 1/2 WAY POINT WORKS CORRECTLY LEFT. REMOVED AND REPLACED RUDDER/AILERON TRIM CONTROL PANEL. C/W AILERON TRIM OPERATIONAL TEST REF DH-8 400 MM 27-13-00-710-802. C/W RUDDER TRIM OPERATIONAL TEST REF DH-8 400 MM 27-22-00-710-801. NO FURTHER DEFECTS NOTED. RETURNED TO SERVICE.