What was found
UPON APPROACH TO LANDING, THE ACFT BEGAN PITCHING UP WITH TRIM RUNAWAY CONDITION. AT THE SAME MOMENT THE TRIM BEGAN THE RUNAWAY CONDITION AN ELECTRONIC BUZZING NOISE WAS HEARD THROUGH THE PILOT'S HEADSET AND CONTINUED UNTIL THE STAB TRIM CIRCUIT BREAKER WAS PULLED TO DEACTIVATE THE STAB TRIM. ACFT WAS RE-TRIMMED USING THE ALT STAB TRIM AND THE MISSION WAS ABORTED AND ACFT RETURNED TO BASE. MX TROUBLESHOT THE SYS WITH THE ASSISTANCE FROM THE MFR AND IT WAS DETERMINED A FAILURE OF THE TRIM RELAY K22. RELAY WAS REPLACED WITH NO FURTHER FAULTS.