What was found
THE HORIZ STABILIZER ACTUATOR FAILED 3.5 HOURS AFTER INSTALLATION. THE CREW REPORTED THAT DURING PREFLIGHT PREPARATIONS THE EMERGENCY/AUTOPILOT MODE OF THE HORIZONTAL STABILIZER ACTUATOR FAILED. THIS ACTUATOR PN 45AS61023-143, SN ET0050 WAS INSTALLED AFTER FAILURE OF SN ET0049 NORMAL FUNCTION MODE ONE DAY BEFORE. BOTH ACTUATORS (S/N ET0050 AND ET0049) WERE O/H. THE HORIZ STABILIZER ACTUATOR SYS WAS TROUBLESHOT AND INTERMITTENT RESISTANCE READINGS WERE FOUND IN THE EMERGENCY/AUTOPILOT MODE OF ACTUATOR MOTOR (ACTUATOR SN ET0050). THE ACTUATOR SN ET0050 WAS REPLACED BY S/N ET0042 AND THE ACFT WAS RETURNED TO SERVICE WITHOUT FURTHER PROBLEMS.