Narrative:

During cruise at FL390 the #3 engine EPR began to increase rapidly while the N1, N2, and egt were decreasing rapidly. Fuel heat was applied to the engine with no results. Condition worsened. Performed 2 rapid engine shutdown/restarts with no effect. Contacted sin control on HF explaining problem and requesting lower altitude. Cleared to FL350, began descent, turned on engine anti-ice. Leveling off at the lower altitude, the engine resumed normal operation. Proceeded to destination with no further problem. Took engine snapshots at FL390 and FL350. WX at time was -51 static air temperature, smooth to mid chop, hazy. Callback conversation with reporter revealed the following information: the reporter stated maintenance could find no probable cause for the engine loss of power. The reporter said the engine was run at all power settings and no malfunction was found. The reporter said the engine was operated eastbound and performed normally. The reporter stated the company operating manual requires anti-ice operation at -40 degrees static air temperature and the airplane was operating at -51 degrees. The reporter said the aircraft was fueled in manila and may have picked up some water in #3 main tank, but the same fuel went in all tanks.

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Original NASA ASRS Text

Title: A B747-200 IN CRUISE AT FL390 HAS #3 ENG EPR INCREASE WITH N1, N2, AND EGT DECREASE. 2 SHUTDOWNS AND RESTART NO HELP. DSNDED TO FL350 WITH ANTI-ICE ON AND ENG OP NORMAL. CAUSE UNKNOWN.

Narrative: DURING CRUISE AT FL390 THE #3 ENG EPR BEGAN TO INCREASE RAPIDLY WHILE THE N1, N2, AND EGT WERE DECREASING RAPIDLY. FUEL HEAT WAS APPLIED TO THE ENG WITH NO RESULTS. CONDITION WORSENED. PERFORMED 2 RAPID ENG SHUTDOWN/RESTARTS WITH NO EFFECT. CONTACTED SIN CTL ON HF EXPLAINING PROB AND REQUESTING LOWER ALT. CLRED TO FL350, BEGAN DSCNT, TURNED ON ENG ANTI-ICE. LEVELING OFF AT THE LOWER ALT, THE ENG RESUMED NORMAL OP. PROCEEDED TO DEST WITH NO FURTHER PROB. TOOK ENG SNAPSHOTS AT FL390 AND FL350. WX AT TIME WAS -51 STATIC AIR TEMP, SMOOTH TO MID CHOP, HAZY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED MAINT COULD FIND NO PROBABLE CAUSE FOR THE ENG LOSS OF PWR. THE RPTR SAID THE ENG WAS RUN AT ALL PWR SETTINGS AND NO MALFUNCTION WAS FOUND. THE RPTR SAID THE ENG WAS OPERATED EBOUND AND PERFORMED NORMALLY. THE RPTR STATED THE COMPANY OPERATING MANUAL REQUIRES ANTI-ICE OP AT -40 DEGS STATIC AIR TEMP AND THE AIRPLANE WAS OPERATING AT -51 DEGS. THE RPTR SAID THE ACFT WAS FUELED IN MANILA AND MAY HAVE PICKED UP SOME WATER IN #3 MAIN TANK, BUT THE SAME FUEL WENT IN ALL TANKS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.