As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 3967 - DURING CRUISE FLIGHT CREW REPORTED A MAIN AND BACKUP TRIM INOPERATIVE WARNING. MAIN SYSTEM WAS RESTORED BY RESETTING BREAKER. BACKUP TRIM WOULD NOT RESTORE. MAINTENANCE LUBRICATED THE BACKUP TRIM SWITCH AND DRAINED THE NR 1 AND 2 PITOT SYSTEM IAW EMB MM. THE HSCU WAS REMOVED AND REPLACED IAW EMB MM. OPERATIONAL CHECK WAS SATISFACTORY AND AIRCARFT WAS RETURNED TO SERVICE. (M)