What was found
DURING CLIMB AFTER CREW REPORTED A POSSIBLE BIRDSTRIKE, THE NR 4 ENGINE COMPRESSOR STALLED TWICE. THE ENGINE RECOVERED FOR 8-10 MINUTES AFTER THE FIRST STALL AND THEN STALLED AGAIN. THE ENGINE WAS SHUT DOWN, FUEL WAS DUMPED, AND THE FLIGHT RETURNED TO ANC. T HE LANDING WAS WITHOUT INCIDENT. METAL DEBRIS WAS FOUND IN THE TAILPIPE. THE ENGINE WAS REPLACED. FURTHER INVESTIGATION FOUND BIRDSTRIKE EVIDENCE ON FAN BLADES AND EXTENDING INTO THE FIRST PORTION OF THE COMPRESSOR CORE.