What was found
AT FLIGHT LEVEL 28,000 AND DESCENDING WHEN THE AUTO THROTTLES RETARDED, A LOUD POP OCCURRED, THE AUTO THROTTLES WENT TO GROUND IDLE, THE EXHAUST GAS TEMPERATURE STARTED TO CLIMB, AT EGT 928 DEGREES CELSIUS. CREW SHUTDOWN THE LEFT ENGINE MANUALLY. UPON ARRIVAL METAL WAS DISCOVERED IN THE TAIL SECTION. REMOVED AND REPLACED NR 1 ENGINE.