What was found
INFLIGHT SHUTDOWN, AIR TURN BACK, DECLARED EMERGENCY AT FL390 CRUISE, NR 1 ENGINE HAD HARD VIBRATION, VIB GAUGE WENT TO 4.9. FOLLOWED BY WHITE BOX AROUND ENGINE INDICATORS LOWER FOLLOWED BY ENGINE ROLL BACK & ENGINE FAIL INDICATOR ON EGT GAUGE. VIBRATION PERSISTED WELL INTO ENGINE SHUTDOWN. NO FIRE, OVER SPEED ALL INDICATION WERE NORMAL UNTIL THE EVENT AT SHUTDOWN NR 2 READ 0. R & R NR 1 ENGINE ASSEMBLY IAW MT.