Fuel imbalance: can it make impossible a 737 flight?

[teopereira 25]

In 2006, a Learjet 35 crashed soon after taking off from Campo de Marte (Sao Paulo, Brazil) allegedly due to fuel imbalance: http://www.pprune.org/biz-jets-ag-flying-ga-etc/299010-lear-35-crashes-into-houses-sao-paulo.html

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My cousin, who is a 737 NG captain, had troubles with fuel pumps on a flight some years ago and had to land with almost twice the allowed fuel imbalance for the 737-800. But he said to me the 737-800 is able to fly with any fuel imbalance.

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In the aircraft mechanics couse I'm attending, the instructor doubted a 737 could fly with much fuel imbalance.

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So, what is your opinion?

 

Thanks,

 

Teo Halfen

[Levkov 8]

My general opinion is that the larger the aircraft the more fuel inbalance it can tolerate. I don't think it would be too much of a problem in the 737, because, if it were, I assume they would have put in a fuel dumping system. If you imagine the situation where one fuel tank has a leak and runs completely dry, and the asociated engine is shut down (as you can't operate fuel crossfead with a fuel leak) you would have a rather serious imbalance, and you could only compensate by dumping some of the fuel from the remaining tank prior to landing.

[davierosoft 13]

Depending on aircraft speed the imbalance is more or less important, with a low speed imbalance could create problems due to the less aileron efficiency.

If there are limits, they are present because aircraft or regulation limits. i don't think there are legal limitations in such case so the problem is purely related to the aircraft.

unbalance is dangerous, it must be avoided.

A 737 did a flight test after a maintenance check, the technician inverted the position of the left and right fuel indicators (737 classic), flight crew had anunbalance and reacted to correct it, but, they increased the problem and they were thinking about a leakage or something else.

Finally they decided to close the crossfeed and they understood that the problem was the in the inverted connectors.