What was found
(CAN) DURING THE PREFLIGHT WALKAROUND THE CREW DISCOVERED DAMAGE AND DELAMINATION OF THE R/H OUTBOARD TRAILING EDGE FLAP. INSPECTION REVEALED THE SKIN HAD DISBONDED FROM THE HONEYCOMB CORE THAT RESULTED IN IT DEPARTING THE AIRCRAFT. IT IS UNKNOWN THE EXACT PHASE OF FLIGHT THIS HAD OCCURED. HOWEVER THE PICTURE WHICH IS ATTACHED INDICATES THE FLAPS WERE LIKELY TO HAVE BEEN RETRACTED AS THE REMAINING PIECE OF SKIN WAS HELD ON BY THE THE CANOE FAIRING. THIS IS A KNOWN ISSUE TO BOEING AND IS DESCRIBED IN ATTACHED FTD 57-14001.