fuel tank venting

[klehman]

Actually one of the easiest mods that I did ;) Back to back 1/8 NPT
flanges on the root rib and a 1/4" aluminum tube along the top of the
spar through the cutouts that are already there at the top of the ribs.
Some proseal to keep it from chafing and a bracket or clip to hold the
outboard end of the tube.
Ken

Ken has an excellent suggestion on venting from the
top front outside corner of the tank, but a bit tricky to get
the tube in place inside the tank, I suspect ...

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[klehman]

Mike

If I understand your question, my plan is one inverted J on the top
right wing root fairing like Wayne and Bob recommended. With cross vent
lines that join at the inverted J. My prop turns clockwise as viewed
from the cockpit.

Draw the wing and tanks with 1 degree of dihedral on each wing. When
pefectly level the outboard side of the tank is something like 0.6
inches higher than the inboard end which is why the fuel cap is out
there. Then tilt your drawing to simulate being parked with a low wing
and satisfy yourself that your fuel won't drain.

Underwing drains pretty much require the vent tube to go to the far side
of the tank so that only small slugs of fuel can escape. And you may not
want to crossvent the way the manual shows if using underwing Vents as
fuel can flow through the crossvent into the low wing. For environmental
reasons, I like the inverted J on the top of the wing so that not even
small slugs of fuel can escape as the fuel sloshes around.

I concluded that I only liked the method that I used if I was going to
crossvent. But I like either an inverted J in the wing root or an
inverted J on both fuel caps. It's easier to remove the fuel caps
without tubes on them though.

Ken

Jones, Michael wrote:

HI KEN

where did you put your vent tubes, one or two, i was thinking of off the
outboard tank rib, one or two or maybe tee of vent holes on inboard rib,
also runing vent tube inside tank from inboard to outbard like you suggested

mike#007

-----Original Message-----
From: klehman@albedo.net [mailto:klehman@albedo.net]
Sent: Friday, April 02, 2004 11:45 AM
To: murphy-rebel@dcsol.com
Subject: Re: Fuel Tank venting


Actually one of the easiest mods that I did ;) Back to back 1/8 NPT
flanges on the root rib and a 1/4" aluminum tube along the top of the
spar through the cutouts that are already there at the top of the ribs.
Some proseal to keep it from chafing and a bracket or clip to hold the
outboard end of the tube.
Ken

Ken has an excellent suggestion on venting from the
top front outside corner of the tank, but a bit tricky to get
the tube in place inside the tank, I suspect ...

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[Murray Cherkas]

Mike:

We all have good opinions. I put three fittings in each end rib. two at the
front ,top and bottom and one at the back on the bottom.Out of the top front
fitting I came into the fuselodge,and put in a "T". Go from the bottom of
the T to the bottom fitting. This is your sight gauge, with clear
tubing.Cross vent to the other side from the T fitting in the fuse.The back
bottom fitting is the fuel line. Come into the fuse, turn 90* install a ball
valva, run down the back of the door post,install a T,run one line up to the
carryhtroughs, across to the middle,install a T, this picks the line up from
the other side which now goes to and through the firewall to a gascolator.

From the other end of the T close to the floor behind the door post, run

another line to a drain through the floor making this the low point in the
fuel lines. This has worked for me for 46 hrs. so far.I vented both fuel
caps. 3/8" tube about 4" high curved into the wind. Don't forget to seal the
holes in the fuel cap. $100 bucks later at a welding shop that knows how to
weld aluminum.

Good Luck

Murray
rebel 505

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
klehman@albedo.net
Sent: Friday, April 02, 2004 10:50 AM
To: murphy-rebel@dcsol.com
Subject: Re: Fuel Tank venting


Mike

If I understand your question, my plan is one inverted J on the top
right wing root fairing like Wayne and Bob recommended. With cross vent
lines that join at the inverted J. My prop turns clockwise as viewed
from the cockpit.

Draw the wing and tanks with 1 degree of dihedral on each wing. When
pefectly level the outboard side of the tank is something like 0.6
inches higher than the inboard end which is why the fuel cap is out
there. Then tilt your drawing to simulate being parked with a low wing
and satisfy yourself that your fuel won't drain.

Underwing drains pretty much require the vent tube to go to the far side
of the tank so that only small slugs of fuel can escape. And you may not
want to crossvent the way the manual shows if using underwing Vents as
fuel can flow through the crossvent into the low wing. For environmental
reasons, I like the inverted J on the top of the wing so that not even
small slugs of fuel can escape as the fuel sloshes around.

I concluded that I only liked the method that I used if I was going to
crossvent. But I like either an inverted J in the wing root or an
inverted J on both fuel caps. It's easier to remove the fuel caps
without tubes on them though.

Ken

Jones, Michael wrote:

HI KEN

where did you put your vent tubes, one or two, i was thinking of off the
outboard tank rib, one or two or maybe tee of vent holes on inboard rib,
also runing vent tube inside tank from inboard to outbard like you

suggested

mike#007

-----Original Message-----
From: klehman@albedo.net [mailto:klehman@albedo.net]
Sent: Friday, April 02, 2004 11:45 AM
To: murphy-rebel@dcsol.com
Subject: Re: Fuel Tank venting


Actually one of the easiest mods that I did ;) Back to back 1/8 NPT
flanges on the root rib and a 1/4" aluminum tube along the top of the
spar through the cutouts that are already there at the top of the ribs.
Some proseal to keep it from chafing and a bracket or clip to hold the
outboard end of the tube.
Ken

Ken has an excellent suggestion on venting from the
top front outside corner of the tank, but a bit tricky to get
the tube in place inside the tank, I suspect ...

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[Bob Patterson]

Hi Jose !

Not sure of your question - If the top guage flange is already
installed, just thread in a 'T' fitting on the cockpit side. One leg
of the tee goes to the top of the fuel guage tube, and the other leg
goes to the vent tube - you could use flexible hose to run this to a
fitting on the wing/fuse gap seal strip, and put an inverted "J"
tube on the outside of this strip.

If you are going to put a tube inside the tank, as Ken has
done, just thread a connecting fitting into the inside of the guage
flange, and connect up the tube to run out to the top front outside
corner of the inside of the tank. Then do the above on the cockpit
side of the flange - should be enough threads for both connections.

The idea of having the tube on top, extending up about 5"+,
is to keep it higher than the fuel could possibly get, even on a slope,
so no fuel could run out the vent. Putting it on the bottom would
almost guarantee the possibility of a siphon condition.

Thursday night IS the Rebel Builders Get-Together - and
the first round of beer is on me, as usual !! See you all there !! :-)

.....bobp

----------------------------orig.-------------------
On Tuesday 23 March 2004 09:26 am, you wrote:

Gentlemen

Thank you all for the lots of suggestions given on the subject.

I will put the vents up at the wing fairing as per Waine's and Bob's
suggestions. In this case, what would be the "safest" slope of the aluminum
tube in relation to the top wing skin in order to prevent syphoning? Or
should it be positioned in paralel to the top wing skin? I understand that
the tube/vent circuit should not have a "depression" between ends, where
fuel could stop and consequently neutralising the venting effect...

Bob / Dale, I have a doubt on your suggestions: HOW to fix the aluminum
tube in the top guage flange, from inside of the tank, using a "T" outside?
The flange is already riveted and prosealed in the root rib, hence my
initial idea of installing a fitting (AN-833-4D) in the root rib, just to
hold the tube in the rib.

Just one more thought on this subject, probably stupid: why not install the
tube vent at the wing fairing but in lower side of the wing (facing down)?
In this way, I think, shyphoning would be literally impossible to take place
(?!)

I hope to meet some of you, personally, at Sun'N'Fun! I understand thursday
will be the meeting day, right Bob?.

Jose / R#700

----- Original Message -----
From: "Bob Patterson" <beep@sympatico.ca>
To: <murphy-rebel@dcsol.com>
Sent: Friday, April 02, 2004 1:16 PM
Subject: Re: Fuel Tank venting

Hi Jose !

You could just tee off the top fuel guage fittings,
as has been suggested, and, I believe, the factory recommends.
There is no problem with this arrangement - there WAS a problem
with tee-ing off the BOTTOM guage fitting for the fuel flow,
but you have avoided that.

Ken has an excellent suggestion on venting from the
top front outside corner of the tank, but a bit tricky to get
the tube in place inside the tank, I suspect ...

In any case, DO NOT put the vent in the center, over the
cockpit ! The last thing you want is a fuel shower overhead !
It would be better to put inverted "J" tubes through the wing
root-to-fuselage fairings, one on each side - this makes them
accessible for service, and keeps any spills clear of the cockpit
& windshield. These can work individually, for each tank, or you
can tee them together with a cross tube - just beware of the
cross-flow of fuel if a large slope is caused by a flat tire or
uneven ground. Just a suggestion !

......bobp

----------------------------orig.-------------------
On Monday 22 March 2004 06:05 pm, you wrote:

Gentlemen

In principle, I intend to install a venting system as per Tony Bingellis
suggestions, i.e. , with a 1/4" aluminum tube in each tank
interconnected in the fuselage with the vent up into the top of cabin
(inverted "T " configuration).

To do this I have to drill an hole in each root solid rib to fit the
aluminum tube, holding it either with a flange or with a threaded
connection.

Is this acceptable? I am bit worried in drilling another hole in the
solid rib (already has 2 for the fuel level and 1 for fuel outlet).
In case this is acceptable, is there a preferential position for those
new holes in the solid ribs?

Other suggested venting configurations would be also welcome.

After this I will be (finally!), in position to install the tank cover
and move to the left wing.

Thanks on advance for you advice(s).

Jose / Brazil - Rebel # 700

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[Jim Cole]

I have a "J" - tube that I built into both caps and it has worked great so
far (touch wood). I've been thinking a lot about installing a small header
tank the same as Ken and that another friend of mine has on his Kitfox.
I did have a hiccup in the engine one day when I was doing steep turns, when
I had less than a 1/4 tank in the right wing tank.
A header tank make sense to me now.

I also happened to be at Found Aircraft in Parry Sound yesterday and one of
the things I took pictures of was the fuel tank vents that they have on the
Bush Hawk. They are hoses cut on an angle protruding from the bottom of the
wing, designed to catch the wind. I posted a couple of pictures under Rebel
Fuel systems - 212.
I unfortunately uploaded a large file 2mb before I realized I had not
grabbed the low rez version - so have an eye - the 2mb version is the same
as one of the other two low rez shots that I up loaded.
I watched the new Found Expedition (trike gear) do some test flying -
they're still working towards their certification. More like a Cadillac than
a bush plane but nicely finished.

Cheers
Jim Rebel 333

On 4/19/2008 2:05 PM, "Ron Shannon" <rshannon@cruzcom.com> wrote:

The upper forward hole is for the cross vent, which is necessary to equalize
pressure in the tanks, such as if one external vent (see below) is plugged
by bugs, for example. Imagine what happens if one tank's external vent is
plugged and there's no cross vent. The tank develops negative pressure --
and the fuel stops flowing down. That may result in fuel starvation and ruin
your day -- whether you inline valves for each tank, or just one valve at
or after the junction of the fuel lines from the two tanks. Regardless, the
cross vent is mandatory. I have some pictures of mine & will try to locate
them.

Of course, you also need the external vents, which could be snorkels coming
up from somewhere in the cross vent, or snorkels in the gas caps. Both
locations will put some positive air pressure into the tanks, which is a
good thing. Putting snorkels in the gas caps may be a little better, because
you don't run the risk of a blockage in the cross vent line between
snorkel(s) and tank(s), and snorkels in the gas caps are easily tested with
a blow when you add fuel, etc.

Not sure about your descriptions of the other holes. The bottom-most hole in
the root rib, about 7-8 inches forward of the torque tube, is for fuel line
output. The hole in the bottom of the wing is for a fuel tester drain.

If you use capacitance probe gauges (or some float gauge type -- as far as
that goes) you'll need to cut a hole for them, per their installation
instructions. See the photo I linked to before, where the capacitance probes
are shown as a roughly 2.5" dia. black "hockey puck" circle near the upper
forward part of the rib, about 2 inches forward of the cross vent
connection.

Ron


On Sat, Apr 19, 2008 at 10:20 AM, Craig Walls <snowyrvr@mtaonline.net>
wrote:

So, if I get this, the upper hole at the front of the root rib would be a
vent to the other tank, the lower hole at the front of the rib would be
for
the fuel gage, and the lower hole at the rear would be for the fuel
pick-up.


In my manual they show a cross vent between the two tanks with a metal
tube
that extends through the roof to get a ram air effect. Not sure if
that's
necessary, could probably do the same thing with those fuel caps with the
ram-air tubes built in.

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