As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FFOD CHECK ON STAB TRIM CH 2 AND MACH TRIM, THE STAB TRIM 2 WOULD NOT STAY ENGAGED DURING THE TEST. REPLACED HORIZONTAL STAB TRIM ACTUATOR AND MOTOR CONTROL UNIT IAW RJ MM 27-42-01, 27-42-05 AND RII CARD 27-415. OPS CHECKS GOOD. ACTUATOR P/N: 8396-3, S/N OFF: 796.