What was found
DURING FLIGHT (CLIMBING AT FL220), ELEVATOR TRIM BECAME STIFF AND DID NOT WORK CORRECTLY. AIRCRAFT PITCHED UP ABRUPTLY WITH AUTO PILOT ENGAGED WITH FL240 SET IN THE ALTITUDE ALERTER. WE DISCONNECTED THE AUTOPILOT, LEVELED THE AIRCRAFT AND MANUALLY TRIMMED THE AIRCRAFT AT A SLOWER AIRSPEED. DECLARED AN EMERGENCY, USED THE EMERGENCY CHECKLIST AND RETURNED TO MEACHAM WITH NO ISSUE. DURING TROUBLESHOOTING THE BREAK OUT TORQUE FOR THE FLAP/ELEVATOR TRIM MIXER P.N. 6565102-15 WAS FOUND TO BE LOW AND WAS ADJUSTED AS NEEDED. VERIFIED FLAP AND ELEVATOR TRIM RIG AND OPERATION.