What was found
PILOT REPORTED, DURING TAKEOFF OUT OF GPZ THE YAW DAMPER DID NOT ENGAGE WHICH WAS THE INDICATION OF AN AUTOPILOT FAILURE. WHEN AUTOPILOT WAS SELECTED IT ALSO DID NOT INDICATE THAT IT HAD ENGAGED EITHER. AUTOPILOT DID APPARENTLY ENGAGE IN THE BACKGROUND AND WOULD NOT RESPOND TO ANY INPUTS. ATTEMPTED TO DISENGAGE AUTOPILOT SEVERAL TIMES WITH EACH DISCONNECT FUNCTION, BUT IT WOULD NOT DISCONNECT AND HAD TO BE MANUALLY OVERPOWER FOR THE REMAINDER OF THE FLIGHT. THERE WAS ALSO NO CAWS PANEL LIGHTS ILLUMINATED. ON THE GROUND BEFORE TAKEOFF THE AUTOPILOT SYSTEM PASSED SELF TEST.