What was found
DURING A PREFLIGHT INSPECTION, WHILE DRAINING THE FUEL SUMP ON THE RIGHT WITN, THE DARIN VALVE BECAME STUCK IN THE OPEN POSITION. THE TOPPED OF WING WAS PROFUSELY DRAINING ON THE HANGER FLOOR. AFTER THE AIRCRAFT WAS DEFUELED AND THE DRAIN VALVE REMOVED. IT WAS DISCOVERED THAT A SMALL PLASTIC TUBE, POSSIBLY A PRIST NOZZLE, HAD WORKED ITS WAY THOUGH THE WING AND INTO THE DRAIN PREVENTING IT FROM CLOSING.