What was found
FLIGHT CREW REPORTED THAT THE HORIZONTAL STABILIZER TRIM FAILED PREFLIGHT TRIM CHECKS. STAB TRIM DID NOT CONSISTANTLY TRIM (UP OR DOWN) WHEN THE PRIMARY OR EMERGENCY TRIM SWITCHES WERE DEPRESSED. THE TRIM MOTOR WAS AUDIBLE BUT INTERMITTENT STAB MOVEMENT WAS NOTED. FULL DOWN TRIM COULD NOT BE ACHIEVED. MX REMOVED THE DEFECTIVE HORIZONTAL STABILIZER ACTUATOR PN 45AS61023-143, SN 061102. AN O/H UNIT WAS INSTALLED, OPS CHECKS WERE SATISFACTORY. TRIM INDICATIONS WERE WITHIN LIMITS. REF MM 27-40-00. A TEARDOWN REPORT WAS REQUESTED FOR THE REMOVED UNIT.