As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) REMOVED LT PNEUMATIC CHECK VALVE TO INSPECT INTERNAL HINGE OPERATIONS. FOUND HINGE PIN DISLODGED (WORKED) TO ONE SIDE, RESULTING IN OFFSET FLAPPER DOOR MOVEMENT, WEAR AND POOR OPERATION. A LONGER HINGE PIN OR STAKING THE ORIGINAL PIN MAY PREVENT THIS TYPE OF MALFUNCTION.