A B-747 air crew experienced an EICAS message warning of a fuel imbalance between tanks 1 and 4. The...

Narrative:

#4 fuel spar valve status message appeared on taxi out. At cruise stab fuel transfer was initiated on schedule. Approximately 5 minutes later EICAS annunciated 'fuel imbalance 1-4'. Stab fuel quantity was 17.0 - fuel synoptic showed #4 tank 3;000 pounds less than #1 with #4 decreasing at a rate of 300-400 pounds / min. The irregular checklist for fuel imbalance did not seem to address our situation.contacted [maintenance control] thru [dispatch] for assistance. Aircraft seemed to be in trim when hand flown. I elected to transfer the remaining stab fuel to the center tank since landing with stab fuel is problematic. #4 fuel quantity continued to decrease during stab transfer and at completion was greater than 7;000 pound imbalance. After consulting with [maintenance control] and [dispatch] I decided a divert would be most prudent and have maintenance check the issue. Fuel was dumped enroute in hopes of reaching landing weight at touchdown; however with an unknown quantity of fuel in #4 tank; landing weight was later found to be 632.0. Maintenance drip sticked fuel on arrival and confirmed #4 fuel quantity was indicating correctly.

Original NASA ASRS Text

Title: A B-747 Air Crew experienced an EICAS message warning of a fuel imbalance between tanks 1 and 4. They consulted with maintenance; dumped fuel; and diverted.

Narrative: #4 fuel spar valve status message appeared on taxi out. At cruise stab fuel transfer was initiated on schedule. Approximately 5 minutes later EICAS annunciated 'FUEL IMBALANCE 1-4'. Stab fuel quantity was 17.0 - fuel synoptic showed #4 tank 3;000 pounds less than #1 with #4 decreasing at a rate of 300-400 pounds / min. The irregular checklist for fuel imbalance did not seem to address our situation.Contacted [Maintenance Control] thru [Dispatch] for assistance. Aircraft seemed to be in trim when hand flown. I elected to transfer the remaining stab fuel to the center tank since landing with stab fuel is problematic. #4 fuel quantity continued to decrease during stab transfer and at completion was greater than 7;000 pound imbalance. After consulting with [Maintenance Control] and [Dispatch] I decided a divert would be most prudent and have maintenance check the issue. Fuel was dumped enroute in hopes of reaching landing weight at touchdown; however with an unknown quantity of fuel in #4 tank; landing weight was later found to be 632.0. Maintenance drip sticked fuel on arrival and confirmed #4 fuel quantity was indicating correctly.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1245247
Time
Date	201503
Local Time Of Day	0601-1200
Place
Locale Reference	ZLC.ARTCC
State Reference	UT
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Fuel Tank
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 24000 Flight Crew Type 1200
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter Fuel Issue

A B-747 air crew experienced an EICAS message warning of a fuel imbalance between tanks 1 and 4. They consulted with maintenance; dumped fuel; and diverted.