As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOST PRIMARY TRIM CONTROL USING THUMB SWITCHES ON PILOTS CONTROL WHEEL DURING APPROACH. EXECUTED MISSED APPROACH AND FLEW APROX 5 MIN WHEN PRIM TRIM CONTROL RETURNED TO PILOTS CONTROL WHEELS. CHECKED BOTH CONTROL WHEEL SWITCHES AT ALL TIMES. REPLACED PRIMARY AND ALTERNATE LONGITUDINAL TRIM ACTUATORS PER M/M. OPS CK PRIMARY AND ALT OK PER M/M. NOT AN RII ITEM.