What was found
(CAN) DURING COLD WEATHER, PRE-DEPARTURE CHECK BY MAINTENANCE PERSONNEL, THE STABILIZER TRIM SYSTEM WAS OPERATED. DURING OPERATION A VIBRATION AND NOISE WAS NOTICED. UPON INVESTIGATION IT WAS FOUND THAT THE BRAKE ASSEMBLIES IN THE STABILIZER TRIM GEARBOX WERE NOT FUNCTIONING CORRECTLY, CAUSING THE VIBRATION AND NOISE. THE STABILIZER TRIM GEARBOX AND JACKSCREW ASSEMBLY WAS REPLACED WHICH RECTIFIED THE DEFECT. INVESTIGATION OF PRIOR FLIGHTS DID NOT SHOW ANY PREVIOUS PROBLEMS.