As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THIS ISSUE INVOLVES SEATBELTS INSTALLED ON AIRCRAFT. THE TENSIONER BAR ON LAP BOLT WILL NOT HOLD TENSION ON BELTS ONCE TIGHTENED. BELTS ARE LOOSENING DUE TO VIBRATION IN FLIGHT. THE TENSION BAR IS SMOOTH, SO IT IS NOT HOLDING TENSION. REDESIGN TENSIONER BAR.