What was found
AC WAS ACQUIRED IN AN OVERHAULED CONDITION FROM AUTO PILOTS CENTRAL. THIS UNIT WAS AN EXCHANGE UNIT WITH AN OVERHAUL DATE OF APPROX, JUNE 2004. THE KI-256 WAS INSTALLED AND MARRIED TO THE EXISTING FACTORY INSTALLED AUTOPILOT SYS IAW INSTALLATION/ SYS MM. AC WAS RETURNED TO SERVICE AFTER A SUCCESSFUL FLIGHT CHECK. ALL AUTOPILOT/ FLIGHT DIRECTOR MODES WERE CHECKED. SINCE THEN THIS FD/HORIZON HAS BEEN REMOVED AND RETURNED TO OVERHAULER NO LESS THAT 3 TIMES. HORIZON HAS BEEN RESPONSIBLE FOR AN ABRUPT AND ERRATIC PURPOSE. THIS UNIT HAS ALWAYS FAILED IN AUTOPILOT PITCH MODE. EACH TIME OVERHAULER FINDS A NEW PROBLEM IN PITCH CIRCUITS. THESE PROBLEMS ARE RELATED TO THE AUTOPILOT IN THE PITCH AXIS, BUT EACH TIM