Dispatched with one main fuel gauge deferred inoperative; a B737-700 flight crew noted that fuel was only being consumed from the tank with the inoperative gauge. An emergency was declared and the flight diverted.
Synopsis
Dispatched with one main fuel gauge deferred inoperative; a B737-700 flight crew noted that fuel was only being consumed from the tank with the inoperative gauge. An emergency was declared and the flight diverted.
Narrative
We departed with the number two flight deck fuel quantity indicator deferred. We completed all the MEL provisions including dripping the fuel tank and proper crossfeed valve operation.During climbout; I commented on the number two fuel indication going down (the side with the bad gauge). Shortly after level off at FL340 a fuel audit indicated a further indicated fuel imbalance. After summing the fuel indicated with fuel burned and subtracting this from the departure fuel; we determined that the indicated fuel imbalance was correct (5;700 LBS in number one and 3;800 LBS in number two). The crossfeed valve indicated closed. Further investigation revealed a popped crossfeed valve circuit breaker. We talked with Dispatch; complied with the Crossfeed Valve Inoperable QRH Checklist; declared an emergency and diverted to a nearby airport.The crossfeed valve indicated closed in flight; but was found to be in the open position by Maintenance. My mistake was confusion about whether or not the crossfeed valve circuit breaker could be reset with the limitation in the FOM.One additional item is that if a Crew declares an emergency; I think they should be pulled from flying at least the rest of that day period. It is very distracting.
Second reporter narrative
We performed a fuel audit based on predeparture quantities and found that fuel was feeding out of right tank exclusively; that is; no fuel was being burned from the left tank. The crossfeed valve indications did not respond when we cycled the crossfeed knob.After assessing our fitness for continued duty; all five crew members expressed the ability to continue with our originally scheduled day. With a new aircraft; we then resumed our duty day. Two legs later; both of us found that our immediate mental situation was still fixated on the diversion scenario from earlier in the day. After discussing this; we both came to the agreement that in any situation; if a flight crew declares an emergency for any reason the flight crew should be relieved of duty upon landing; period. They should be given the option of dead heading either home or straight to their scheduled overnight; no questions asked. We need time to mentally de-brief the situation; write our narratives and file the appropriate paperwork then; instead of continuing and trying to resurrect it later. But in any event; they should be done with flying for that day; no questions asked.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.