What was found
AT 4,500 FEET ON APPROACH, THE NR 4 ENGINE FLAMED OUT WHILE AT IDLE POWER. THE ENGINE WAS RESTARTED AND OPERATED NORMALLY FOR THE REMAINDER OF THE FLIGHT INCLUDING REVERSE AND TAXI OPERATION. MAINTENANCE INSPECTED THE ENGINE INCLUDING CHIP DETECTORS AND FUEL FILTER WITH NO DISCREPANCIES NOTED. THE FUEL TANKS WERE SUMPED AND THE FUEL FILTER WAS REPLACED. AN ENGINE OPERATIONAL TEST WAS PERFORMED WITH ALL INDICATIONS NORMAL.