As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF AT ALTITUDE WHEN THE AUTOPILOT WAS TURNED ON THE TRIM WOULD RUN NOSE UP IMMEDIATELY. EACH AUTOPILOT WAS TRIED WITH SAME RESULTS, RETURN TO DFW. REPLACED RIGHT ELEVATOR NEUTRAL SHIFT TRANSDUCER, OPS CHECK GOOD. PERFORMED ALL REQUIRED CHECKS. (M)