As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON THE AIRCRAFT'S THIRD LEG OF FLYING THE CREW REPORTED THAT THE PRIMARY PITCH TRIM SYSTEM HAD FAILED. MAINTENANCE TROUBLESHOOTING DETERMINED THAT THE HORIZONTAL STAB TRIM CONTROL BOX WAS FOUND TO BE DEFECTIVE P/N 6627401000-00 S/N OFF: D0174. THE CONTROL BOX WAS REPLACED WITH A REPAIRED UNIT AND RETURNED TO SERVICE. WE OPERATE A NUMBER OF LEARJET 45 AIRCRAFT, AND THE STAB TRIM CONTROL BOX IS A HIGH FAIL RATE COMPONENT.