SPARKS WERE REPORTED FROM A B747-400'S ENG ON TKOF BUT THEY SUBSIDED. AT CRUISE THE ENG FAILED. AN EMER WAS DECLARED WITH A RETURN TO LAND.

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ACFT MAINT HISTORY SQUAWKED #1 ENG HAD BEEN OBSERVED SPARKING ON TKOF AND CLBOUT OUT OF ZZZZ THE PREVIOUS DAY BUT INSPECTION REVEALED NO PROBS. THIS WAS NOTED IN PREFLT PLANNING. AFTER TKOF FROM ZZZ ON THE 1ST; FLT ATTENDANTS CALLED THE COCKPIT TO RPT SPARKS OBSERVED FROM ENG #1. ALL ENG PARAMETERS WERE COMPLETELY NORMAL AT THAT TIME; SO MAINT CTL WAS CONTACTED USING A PHONE PATCH TO DISPATCH ON THE SATPHONE. AT THIS TIME; SPARKS HAD SUBSIDED AND WITH ALL ENG PARAMETERS NORMAL THE CONFERENCE ENDED WITH ALL IN AGREEMENT TO WATCH ENG PERFORMANCE. NOT LONG AFTER THE CALL; A BUMP AND YAW WAS FELT IN THE AIRFRAME. I IMMEDIATELY NOTICED THE CTL WHEEL ROLL TO THE R; AND THE #1 RPM ROLL DOWN AND THE EGT RISING RAPIDLY. I RETARDED THE THROTTLE AND ASKED THE FO TO PERFORM THE QRC ACTIONS. THE RELIEF FO'S CAME FORWARD FROM THE BUNKS AS THEY HAD FELT THE YAW TOO; AND BEGAN TO HELP WITH COM. WE SENT AN EMER MESSAGE TO ZZZ1 ATC VIA CPDLC AND INFORMED THEM THAT WE HAD LOST AN ENG AND WOULD NEED TO DSND AND RETURN TO ZZZ RIGHT AWAY. NO RESPONSE CAME QUICKLY SO WE TURNED 90 DEGS TO THE S; TURNED ON ALL EXTERNAL LIGHTS AND MADE A RPT ON 121.5 MHZ. SHORTLY AFTER THAT WE GOT A CLRNC TO DSND TO FL240. WE USED HF RADIO TO CALL ZZZ2 RADIO; AND ATTEMPTED TO GET ASSISTANCE FROM THEM. WHEN THAT DID NOT GET RAPID RESULTS; I CALLED DISPATCH ON THE SATPHONE AND ASKED THEM TO CALL ATC AND COORDINATE A CLRNC PRESENT POS DIRECT TO ABC DIRECT TO ZZZ. THAT WAS ACCOMPLISHED AND WE LOADED THE CLRED RTE ON RTE 2. THE PURSER CAME TO THE COCKPIT AND WAS BRIEFED ON THE SIT. I ADVISED HER TO PREPARE FOR A NORMAL LNDG WITHOUT A CABIN PREP. FUEL DUMPING WAS COMMENCED SHORTLY THEREAFTER AS THE EICAS SHOWED A DUMP TIME REQUIRED OF ABOUT 55 MINS. WE DUMPED APPROX 155000 LBS AND DUMPING WAS COMPLETED NOT TOO FAR E OF ABC INTXN AT XA27Z. A BRIEF WAS CONDUCTED FOR AN APCH TO ILS AT ZZZ AND THE EQUIP WAS STANDING BY. TOUCHDOWN WAS AT XB01Z; AND WE TAXIED TO GATE UNDER OUR OWN PWR. PAX WERE WELL ACCOMMODATED BY THE CS STAFF. I CONTACTED THE CREW DESK AND ADVISED THE OTHER COCKPIT CREW MEMBERS THAT WE HAD BEEN RELEASED.