What was found
MACH TRIM AND STAB TRIM CAUTION MESSAGES INFLIGHT AT CRUISE ALTITUDE. CLEANED PILOTS SIDE SWITCH. PERFORMED TEST OF HSTCU, OPERATIONAL CHECK GOOD.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
MACH TRIM AND STAB TRIM CAUTION MESSAGES INFLIGHT AT CRUISE ALTITUDE. CLEANED PILOTS SIDE SWITCH. PERFORMED TEST OF HSTCU, OPERATIONAL CHECK GOOD.