As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, THE RUDDER TRIM KNOB LOST ITS SPRING BACK TO CENTER ABILITY. RUDDER TRIM STILL WORKED FINE, BUT KNOB WOULD NOT RETURN TO 12 O'CLOCK WHEN RELEASED. RETURNED TO FIELD. LANDING UNEVENTFUL. R & R AILERON/RUDDER TRIM CONTROL-PANEL IAW AMM TASK 27-13-16-000-801. PERFORMED OPS TEST OF THE RUDDER TRIM SYSTEM IAW AMM TASK 27-22-00-710-801. OPS TEST GOOD. PERFORMED OPS TEST OF THE AILERON TRIM SYS IAW AMM TASK 27-13-00-710-802. OPS TEST GOOD. NO FURTHER DEFECTS NOTED. RETURNED TO SERVICE.