As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STAB TRIM CHANNEL 2 WILL NOT ENGAGE. FAILED TRIM TEST ON GROUND DURING PREFLIGHT. ON TWO STAB TRIM TESTS CHANNEL 2 FAILURE INDICATED ON HSTCU TEST PANEL. REPLACED HSTCU IAW CL600 MM 27-42-05. STAB CHANNELS AND MACH TRIM TEST GOOD ON GROUND. AIRCRAFT OK FOR CAT II.S/N: 165 S/N OFF: 796.