As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AIRCRAFT WAS COMPLETING A SCOOPING RUN WHEN THE LT HAND DOOR ASSEMBLY PN 215-33006-882 OPENED AND DEPARTED THE AIRCRAFT. CREW WERE ABLE TO LIFT AIRCRAFT OFF WATER AND RETURNED TO BASE WITHOUT FURTHER INCIDENT. INVESTIGATION TO FOLLOW TO DETERMINE THE CAUSE OF DOOR OPENING.