737 "losing" fuel?

Just fuel venting - nothing more. The main tanks are actually vented into surge tanks on the outer section of the wing and that just regulates the quantity and pressure of the fuel in the main tanks. It looks bad though...As I recall, the 747 has something similar, and probably others.
 
It's the new United fuel savings plan. If you dump it out, you don't have to burn all that extra fuel hauling it around. Plus, all the people living at the end of the runway who are always squawking about the noise, gets a new roof and car coating now and then. It's a win-win for everybody.
 
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CaptBill said:
Just fuel venting - nothing more. The main tanks are actually vented into surge tanks on the outer section of the wing and that just regulates the quantity and pressure of the fuel in the main tanks. It looks bad though...As I recall, the 747 has something similar, and probably others.
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We're the tanks overfilled or something, causing this?
 
Possibl
Maximillian_Jenius said:
We're the tanks overfilled or something, causing this?
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Possibly. This is where overfilled fuel tanks would overflow. This vent actually has several uses but it mostly regulates pressure (and prevents a vacuum) as fuel is used in the two wing tanks and the center tank contained in the fuselage. I've seen airplanes taxi out that have been overfilled and it looks pretty strange having fuel pour out of these vents. But, it's perfectly normal. unlike me.
 
CaptBill said:
Possibl


Possibly. This is where overfilled fuel tanks would overflow. This vent actually has several uses but it mostly regulates pressure (and prevents a vacuum) as fuel is used in the two wing tanks and the center tank contained in the fuselage. I've seen airplanes taxi out that have been overfilled and it looks pretty strange having fuel pour out of these vents. But, it's perfectly normal. unlike me.
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Given that they take extra magazines out to save weight these days, isn't that ludicrously wasteful?
 
I don't know the specifics of why it was happening but a DL 747 did this the other day off of 4R in DTW and blanketed the BC ramp in jet fuel.

Maybe that was the big Endeavor announcement? I know I would be applying right away if I found out I could fly CRJs kissed by DL 747 Jet-A vapors.
 
Remember the fuel is pumped into the tanks at a given temperature. If they top the tanks off on a hot day, it's safe to assume that the fuel's characteristics will change. As the plane taxies out and the fuel sloshes around and expands, it's got to have some place to go. You would think they could recover it somehow, but the vent drain is used for multiple purposes, so I assume it just became the most efficient way to deal with the fuel that just needs someplace to go. It doesn't happen often, but it does happen, particularly in the summer months.
 
As others have said, it is not common, but the system is supposed to work that way to prevent over pressure. During ground ops, fuel tends to slosh around and some settles in the surge tanks. During liftoff, the Venturi created by the airflow will suck that fuel out, creating an initial stream that quickly stops.
 
It's mostly due to the temperature changes in the fuel. Happened all the time when I would bag out P-3s at 0 dark 30 for a noon launch. Was fun to watch is piss fuel as it taxied out, every time the wings flexed from bouncing it would drop another patch.

When you fuel a plane early in the day, or with fuel that has been underground or some other large cold soaked pool, it will begin to expand out in the heat of the day. Bagged tanks overflow to the surge chambers and into the surge tanks. Tanks on our 707 airframe only hold about 16 gallons, doubt this 737's tanks are any bigger.

The tanks are designed to drain back into the most outboard fuel tank. However, if that tank is full, nowhere to go but overboard.
 
CaptBill said:
Possibl Possibly. This is where overfilled fuel tanks would overflow. This vent actually has several uses but it mostly regulates pressure (and prevents a vacuum) as fuel is used in the two wing tanks and the center tank contained in the fuselage. I've seen airplanes taxi out that have been overfilled and it looks pretty strange having fuel pour out of these vents. But, it's perfectly normal. unlike me.
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How do you account for this loss? This would make the automation incorrect right? Surprised that this isn't taken into account with some formula with dispatch. Want to hire me to do that math? 8)
 
ComplexHiAv8r said:
How do you account for this loss? This would make the automation incorrect right? Surprised that this isn't taken into account with some formula with dispatch. Want to hire me to do that math? 8)
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Its not enough to account for, but, we can designate you the fuel vent CEO. It doesn't pay much but what does in aviation?
 
CaptBill said:
Its not enough to account for, but, we can designate you the fuel vent CEO. It doesn't pay much but what does in aviation?
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I would think it would add up over the day to lost fuel in cost though. I may be cheap, but I'm not easy.
 
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