PPVRA
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I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 1:30 pm

Was I mistaken or is there something not right in the following pic:


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Photo © Malcolm J.Bezzina

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avt007
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 1:47 pm

If it is fuel, it may just be from a vent. It looks like they are climbing out, with a full fuel load.
 
kbfispotter
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 2:13 pm

Quoting Avt007 (Reply 1):
If it is fuel, it may just be from a vent.

It is streaming from the area of the fuel vent, so this is a possibility.

Kris
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MD11Engineer
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 2:33 pm

The flaps are extended, and the fog comes right from the O/B edge of the flap. I'd rather say that it is just condensation caused by the vortex at the edge of the O/B flap.

Jan
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kbfispotter
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 2:56 pm

Quoting MD11Engineer (Reply 3):
I'd rather say that it is just condensation caused by the vortex at the edge of the O/B flap.

But if you look at the location where the fog starts, it is outboard of the O/B edge of the O/B flap, and it starts in the location of the fuel vent, which tells me it is coming from there.

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LTU932
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 3:12 pm

If this was a fuel dump, wouldn't there have to be a nozzle somewhere on the trailing edge of the wing from where the fuel would be dumped?
 
doug_or
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 3:30 pm

RE: narrowbodies, the 727 has dump capabilities, and I think other early jets did as well (707 DC-8, etc).
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kbfispotter
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 4:58 pm

Quoting LTU932 (Reply 5):
If this was a fuel dump, wouldn't there have to be a nozzle somewhere on the trailing edge of the wing from where the fuel would be dumped?

This is not a fuel dump. What most likely happened is that fuel epxanded in the tanks due to increased temperatures and simply overlowed throught the fuel tank vent on the outboard wing. It happens often, and I have witnessed it several times. It even happens all the time on light aircraft.

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HAWK21M
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Fri Feb 16, 2007 5:20 pm

Looks like Vapours emmitting from the Fuel Vent.Looks like the Aircraft was fuelled to capacity & the Expansion due Temp rise has caused the Spillege.Can occur on Ground too.
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PPVRA
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 12:56 am

Interesting, thanks guys! Didn't know of the existence of fuel vents till now.
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Starlionblue
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 2:38 am

Quoting PPVRA (Reply 9):
Didn't know of the existence of fuel vents till now.

Fuelers love them since they sometimes get to take impromptu showers while standing under them. Big grin
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citationjet
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 3:43 am

According to Boeing Website the following fuel jettison capability:
http://www.boeing.com/commercial/airports/faqs/fueldump.pdf

707 - yes
717 - no
720 - yes
727 - yes
737 - no
BBJ - no
747 - yes
757 - no
767-200/300 - **
767-400 - yes
777 - yes
787 - yes
DC-8 - yes
DC-10 - yes
MD-11 - yes
MD-80 - no
MD-90 - no

** Early models did not have fuel jettison capability, although airlines could install capability. Later models had jettison capability.
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
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LTU932
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 4:41 am

Quoting KBFIspotter (Reply 7):
This is not a fuel dump.

That was the same conclusion I got to, hence my question, just to be sure.
 
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 5:03 am

Quoting PPVRA (Reply 9):
Interesting, thanks guys! Didn't know of the existence of fuel vents till now.

Fuel vent is not really the right word for them. They are fuel tank air vents.
On the ground when fuel is being pumped into the tanks, the displaced air comes out of here.
In flight the fwd facing NACA duct provides a slight (about 2psi) positive pressure on the fuel in the tanks.
During refuelling, if something goes wrong, fuel can end up in the vent surge tank at the wingtip. This usually hols only air, but it has been known for crews to put a couple of hundred kilos of fuel in there for a very long range flight. (illegally!) It is this fuel which you can see venting on take off in the picture. I have seen it happen with a US registered B757 leaving Europe.
The B747 is partcularly prone to this on the ramp because as the wing bends down with a full load of fuel, the vent intake ends up at the lowest point in the tank! The wing rises during the take off roll so in flight it is higher up. (Never try and store fuel in here on a B747)
 
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 5:15 am

Quoting KBFIspotter (Reply 2):
It is streaming from the area of the fuel vent, so this is a possibility.

The fuel tank air vent is much, much more closer to the wingtips than that location in the pic. Its probably about 10-12" or so from the wingtips.

Quoting KBFIspotter (Reply 7):
This is not a fuel dump.

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GQfluffy
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 6:08 am

I'd say someone just used one of the lavs...
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747400sp
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 1:50 pm

Quoting CitationJet (Reply 11):
According to Boeing Website the following fuel jettison capability:
http://www.boeing.com/commercial/airports/faqs/fueldump.pdf

707 - yes
717 - no
720 - yes
727 - yes
737 - no
BBJ - no
747 - yes
757 - no
767-200/300 - **
767-400 - yes
777 - yes
787 - yes
DC-8 - yes
DC-10 - yes
MD-11 - yes
MD-80 - no
MD-90 - no

** Early models did not have fuel jettison capability, although airlines could install capability. Later models had jettison capability.

Wow ! How dangerous, any jetliner should be able to jettison fuel for safety reason.
 
dw747400
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 2:10 pm

Quoting 747400sp (Reply 16):
Wow ! How dangerous, any jetliner should be able to jettison fuel for safety reason.

It is perfectly safe... depending on the nature of the emergency the aircraft can either hold for a few hours, or make an overweight landing. Remember, the narrow-bodies have significantly less fuel aboard than a heavy on an international flight.
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kbfispotter
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 2:31 pm

Quoting AirframeAS (Reply 14):
The fuel tank air vent is much, much more closer to the wingtips than that location in the pic. Its probably about 10-12"

Actually on the 733 thru 735, it is about four to five feet from the wing tip. The area outboard the fuel vent is three interconected open bays. On WN mx task cards, these three bays are refered to as TAI exhaust bays.

http://www.b737.org.uk/fueltankvent.jpg
Here is a photo of the vent in question... The fuel tank vent is on the left, and on the right is the surge tank pressure relief valve. The fuel vent is outboard in this photo of the right wing of a 735. The wing tip is another four to five feet outboard from the vent.

http://www.b737.org.uk/surge_tank_venting.jpg
Here is a similar photo of the one in question... the mist is coming from the same location as in the one above.

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L-188
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 2:31 pm

I agree with the others who say it is vapor comming out of a vent.

Back to the original question, AFAIK (without looking up the specific reg) is that any aircraft that has a MTOW heavier their the MLW is required to have the capability to dump fuel so that in an emergency it can make a landing at a weight below the MTOW.

The spread between MTOW and MLW generally is wider on longer legged aircraft, sometimes adding up thousands (tens of?) pounds of difference.
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OPNLguy
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 3:27 pm

Quoting L-188 (Reply 19):
Back to the original question, AFAIK (without looking up the specific reg) is that any aircraft that has a MTOW heavier their the MLW is required to have the capability to dump fuel so that in an emergency it can make a landing at a weight below the MTOW.

Excerpted from: http://en.wikipedia.org/wiki/Fuel_dumping. Most of it is my writing...

As jets began flying with U.S. airlines in the late 1950s and early 1960s, the FAA rule in effect at the time mandated that if the difference between an aircraft's maximum structural takeoff weight and its maximum structural landing weight was greater than 105%, the aircraft had to have a fuel dump system installed. Accordingly, aircraft such as the Boeing 707 and 727, and Douglas DC-8 had fuel dump systems. Any of those aircraft needing to return to a takeoff airport above the maximum structural landing weight would simply jettison an amount of fuel sufficient to reduce the aircraft's total weight to below that maximum structural landing weight limit, and then land.

During the 1960s, Boeing introduced the 737, and Douglas the DC-9, the original models of each being for shorter routes, and the 105% figure was not an issue, thus they had no fuel dump systems installed. During the 1960s and 1970s, both Boeing and Douglas "grew" their respective aircraft as far as operational capabilities were concerned via Pratt and Whitney's development of increasingly powerful variants of the JT8D engines that powered both aircraft series. Both aircraft were now capable of longer duration flights, with increased weight limits, and complying with the existing 105% rule became problematic due to the costs associated with adding a fuel dump system to aircraft in production. Considering the more powerful engines that had been developed, the FAA changed the rules to delete the 105% requirement, and FAR 25.1001 was enacted stating a jettison system was not required if the climb requirements of FAR 25.119 (Landing Climb) and FAR 25.121 (Approach Climb) could be met, assuming a 15-minute flight. In other words, for a go-around with full landing flaps and all engines operating, and at approach flap setting and one engine inoperative, respectively.
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Starlionblue
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 17, 2007 9:31 pm

Quoting 747400sp (Reply 16):
Wow ! How dangerous, any jetliner should be able to jettison fuel for safety reason.

I think you are assuming that fuel dump capability is installed to decrease the risk of fire/explosion during an emergency landing. This is not the case. If the plane is about to crash into the ground no amount of fuel dumping will change the situation.

It is installed to decrease landing weight for an emergency early in the flight. For a narrowbody, this is not needed. Also, a narrowbody can simply fly around and burn off fuel in some cases. This would take too long in a widebody.
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HAWK21M
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sun Feb 18, 2007 10:36 am

Quoting TristarSteve (Reply 13):
The B747 is partcularly prone to this on the ramp because as the wing bends down with a full load of fuel, the vent intake ends up at the lowest point in the tank! The wing rises during the take off roll so in flight it is higher up. (Never try and store fuel in here on a B747)

Wasn't there a Similar Incident a few years ago where Pax refused to fly an Airline after Fuel poured out of the Vents during Taxi Twice.

Quoting 747400sp (Reply 16):
Wow ! How dangerous, any jetliner should be able to jettison fuel for safety reason



Quoting L-188 (Reply 19):
any aircraft that has a MTOW heavier their the MLW is required to have the capability to dump fuel so that in an emergency it can make a landing at a weight below the MTOW.

 bigthumbsup 

regds
MEL
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AirframeAS
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Wed Feb 21, 2007 3:08 am

Quoting KBFIspotter (Reply 18):
Actually on the 733 thru 735, it is about four to five feet from the wing tip.

Thats about right. I just didnt have my 734 manual in front of me from AS. But close enough.
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HAWK21M
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RE: I Thought Narrowbodies/B737s Couldn't Dump Fuel?

Sat Feb 24, 2007 8:33 pm

http://www.b737.org.uk/fuel_tank_vent.htm
regds
MEL

[Edited 2007-02-24 12:35:12]
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