As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER I5 HOURS INTO A GEOSURVEY FLIGHT WITH A POD ON THE CARGO HOOK, THE CARGO HOOK SUDDENLY RELEASED ON ITS OWN, LOSING AN EXPENSIVE PIECE OF EQUIPMENT. DISASSEMBLY OF THE CARGO HOOK REVEALED THAT THE MECHANICAL RELEASE PIN WAS MISSING PREVENTING THE RELEASE LEVER FROM RETURNING TO ITS FULLY LOCKED POSITION.