What was found
(CAN) CREW REPORTED ABNORMAL AILERON CORRECTION REQUIRED AT FLAPS 15 OR GREATER INBOUND TO YQM. ON INSPECTION IT WAS FOUND THAT THE RIGHT HAND FORWARD INBD FORE FLAP HAD SPLIT OPEN AT THE SPAR. THE FLAP WAS REPLACED AND AIRCRAFT RELEASED. UPON INSPECTION OF FLAP IN SHOP, IT WOULD APPEAR THAT THE AFT HONEYCOMB SECTION HAS SEPARATED FROM THE SPAR DUE TO DISBONDING OF THE JOINT. FURTHER INVESTIGATION REVEALS THAT THE SPAR WAS NOT PROTECTED BY PRIMER AND THE BONDING WAS SPORADIC PERHAPS ONLY 20-30% OF THE WHOLE LENGTH OF THE FLAP.