2 INBOARD ENGS ON 4 ENG WDB FLAME OUT WHILE IN CRUISE FLT IN LIGHT TURB.

Narrative

FLT DEPARTED TOKYO'S NARITA ARPT FOR HONG KONG ON 7/92. THE ACFT WAS A WDB. DEP FROM NARITA WAS NORMAL; WITH SOME OCCASIONAL LIGHT CHOP IN THE CLB. FLT CLBED TO CRUISE ALT OF FL390 WITH ALL SYSTEMS NORMAL; AND ACFT IN VMC FLT CONDITIONS. WE WERE CRUISING ON OUR ASSIGNED RTE OF A-1 JUST PASSED MJE; WHEN APPROX 100 MI SW OF OSAKA; JAPAN WE EXPERIENCED A MOMENTARY OCCURRENCE OF LIGHT TURB (15 SECONDS). ENG IGNITION WAS SELECTED TO FLT START PRIOR TO ENTERING TURB. AT THAT MOMENT I NOTICED ENG #2 ROLL-BACK TO IDLE. APPROX 30 SECONDS LATER ENG #3 ROLLED BACK TO IDLE. WE REQUESTED AN IMMEDIATE DSCNT; AND TOKYO ATC CLRED US TO FL350. CAPT CALLED FOR THE ENG FAILURE CHKLIST; SO AND MYSELF PERFORMED THE REQUIRED ITEMS TO SECURE THE FAILED ENGS. AN ADDITIONAL REQUEST TO DSND TO A LOWER ALT WAS GRANTED BY TOKYO ATC; SO WE CONTINUED TO FL280. ENG INSTS WERE IN THE REQUIRED RESTART PARAMETERS; SO RESTART PROC WAS PERFORMED ON ENGS #2 AND #3; BOTH ENGS RESTARTED WITH NO IRREGULARITY. WE REQUESTED A CLB TO FL350 AND CONTINUED FLT TOWARDS HONG KONG. WE CONTACTED COMPANY DISPATCH VIA ACARS; REGARDING OUR PROBLEM. WE DISCUSSED OUR SITUATION; AND MADE THE DECISION TO LAND IN TAIPEI IF THE PROBLEM RECURRED. WX WAS POOR AND VISIBILITY LOW IN JAPAN DUE TO A STATIONARY FRONT. WE SELECTED TAIPEI BECAUSE OF EXCELLENT WX CONDITIONS AND LONG RWYS IN CASE OF EMER LNDG. AS WE APCHED TAIPEI ENGS WERE PERFORMING NORMAL; SO WE ELECTED TO CONTINUE TO HONG KONG. ON ARR IN HKG; LOGBOOK ENTRY WAS MADE REGARDING OUR INCIDENT. ENG OP RPT AND WHITE LINE FIGURES WERE PERFORMED INFLT. SUPPLEMENTAL INFO FROM ACN 215665. AT 390; WX WAS CLR AND WE EXPERIENCED AN OCCASIONAL LIGHT TURB. 45 MIN AFTER TKOF; WE GOT A 'MODERATE BUMP.' 15 SECONDS LATER #2 ENG SPOOLED DOWN; FOLLOWED BY #3 ENG AS WELL. THERE WERE NO FIRE INDICATIONS OR SPIKES IN EGT'S. WE DID FEEL AND HEARD A SOFT 'POP'; BUT NOTHING AT ALL LIKE A COMPRESSOR STALL. OUR ACFT CONFIGN WAS FL390 ABOUT 555000 POUNDS TANK TO ENG FUEL; MINUS 57 DEG CFF 5500 POUNDS; ECPR 1.47 NO PMS; NO AUTOTHRUST USED; #1 IGN SYS ON.