As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED AFTER DEPARTURE WHEN PILOT TRIED TO TRIM STABILIZER BOTH CHANNELS DISCONNECTED. AFTER ABNORMAL CHECKLIST WAS PERFORMED CREW WAS ABLE TO CONNECT CHANNEL 2. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOOT TO FAULT HSTCU BOX.