As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED ELECTRIC PITCH TRIM RUNAWAY IN THE NOSE DOWN DIRECTION. AURAL "TRIM RUNAWAY" WARNING ACCOMPANIED BY HIGHER THEN NORMAL NOSE DOWN FORCE ON CONTROL WHEEL. PILOT ACTIVATED TRIM INTERRUPT SWITCH AND RETURNED FOR LANDING. MAINTENANCE FOUND PITCH TRIM DOWN RELAY STUCK PN ES215-1423B, PILATUS PN 974.20.01.212. NEW RELAY WAS INSTALLED AND AIRPLANE RETURNED TO SERVICE.