NR TOKYO, PO, JA
N157UA
BOEING 747-123
UNITED FLT 97 EXPERIENCED INDICATIONS OF UNEVEN FUEL FLOW FROM MAIN TANKS 2 AND 3 AT FL360 BEGINNING ABOUT 4- HOURS AFTER DEPARTURE ON AN 11-HOUR TRANSPACIFIC FLIGHT. THE FUEL SYSTEM HAD BEEN SET UP FOR ALL ENGINE FEED FROM THE NOS 2 AND 3 TANKS. ALTHOUGH IT WAS LATER ESTABLISHED THAT THE NUMBER 2 CROSSFEED VALVE FAILED IN THE CLOSED POSITION, THE S/O INFORMED THE CAPT THAT THE INTRANSIT LIGHT HAD ILLUMINATED WHEN THE VALVE SELECTOR WAS MOVED TO THE CLOSED POSITION - INDICATING NORMAL CROSSFEED VALVE OPERATION. FUEL SYSTEM PROBLEM WAS MISDIAGNOSED AS A PROBLEM OF FAULTY FUEL GAGE INDICATIONS. FUEL MONITORING INDICATED INSUFFICIENT FUEL FLOW FROM NO 2 TANK WHEN CROSSFEEDING. ENGS 1, 3, AND 4 FLAMED OUT WHEN FUEL WAS EXPENDED FROM ALL TANKS EXCEPT NO 2. EMERGENCY DESCENT WAS MADE TO DESTINATION TOKYO-NARITA AIRPORT. CREW REPORTED THEY USED FLAPS-20, BUT DFDR SHOWED FLAPS-1 WAS USED FOR LANDING. 3 TIRES BLEW ON LANDING. ALL 3 FLIGHTCREW QUALIFIED IN THE B-747 IN THE 13-MONTHS BEFORE THE INCIDENT.
Source: NTSB Aviation Accident Database
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