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Ed Cesnalis

Fuel vent - green dot forward

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I recently had a fuel issue and we talked about it.  I picked a poor name for the thread so it got deleted to not give the wrong impression.

 

Subsequently I found that my vents were off by 30 degrees so today I added 25 gallons and made the vents face forward and then flew for 2 hours.  My fuel usage was even again, 5-gallons from each side without much trying.

 

The vents on a CTSW if not strait seem to make a difference. 

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On any aircraft that you can use both tanks simultaneously, if there is a pressure differential between the tanks, it will drain unevenly. The vents have to be positioned carefully.

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Hi Jacques.  When new, the vents had green dots on them to signify this was the forward face.  It was a green "sticky" and is probably gone on older CTSW's or CT2K's.  My 2006 still has them.  FWIW, the vents on the CTSW has a skirted top, kind of like a tuxedo coat, with longer tail positioned to the rear.  I assume this skirt catches airflow and produces a slight pressurization of the fuel tank.  If one skirt is positioned forward, this either doesn't provide the pressurization or even produces low pressure while the correctly positioned one on the other tank is providing pressure.  This will cause uneven fuel usage from the tanks.

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Hi Granpa Dick, <_< thanks for the info on the green dot.

My 'vintage' 2005 didn't have that.

Turning the vents is how I manage my fuel burn

left side facing forward and the right  at ~30° leaving more fuel(weight) in the right wing

as I don't have the ailerons / rudder trims.

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maybe,,,,never tried it and have no intention 

but I don't need a green dot to tell me which way it goes,

simple logic..my name is not Barnath <_<

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Hi Andy,

Back in 2007 when I was doing wing fuel flow test I clocked each vent 90 degrees to test them. There is no real appreciable difference. The fuel doesn't get sucked out and the pump makes sure it flows. That said the green dot or more open side of the fuel vent should be forward.

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Hi Andy,

 

Back in 2007 when I was doing wing fuel flow test I clocked each vent 90 degrees to test them. There is no real appriable difference. To fuel doesn't get sucked out and the pump makes sure it flows. That said the green dot or more open side of the fuel vent should be forward.

 

Good to know, thanks!

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Hmmmm, maybe Jacques has an interesting thought.....if one has one tank that consistently feeds faster than the other, turn the vent on this side to lesson the pressure induced from the vent skirt.  As Roger indicates, the effect @ 90 degrees is not noticeable but maybe the effect when @ 180 degrees may result in slower flow from the "HI" flow side?

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Have have tried all that. I also have different vents that all that are 6" tall and have a 90 degree arching sweep forward like some of the old time tank vents. That's positive pressure. I found nothing with vents that made a difference.

 

Now loose your fuel cap and fly and you will loose fuel for sure.

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I'm supposed to be retired, but we can see how well that's working out and it's okay i like what I do.

I'll be at another Rotax school this coming week.

 

p.s.

You get all the sleep you want when you die. I can catch up then.  :P

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Here is a picture of a fuel cap vent for an SW. It does not change any fuel feed properties, but it does keep any fuel from sloshing out when full.

 

https://picasaweb.google.com/116835195307984673307/CTFlierFuelCapVentsAndWingHoseAccess

 

 

Here are two more pictures of holes drill to access the rubber hose for the fuel tank outlet fitting up by the fuel sight tube. Notice the fuel injection clamp with an Allen head. This makes life easy for whom ever needs to get back in here for the life of the plane. Done with a Dremel tool. Also notice the white air hoses on the bottom of the hole. I protect these with the blade of a putty knife while grinding out the hole.

When done just use a piece of Bolus tape over the hole like the wing root tape.

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Here is a picture of a fuel cap vent for an SW. It does not change any fuel feed properties, but it does keep any fuel from sloshing out when full.

Nothing attached.

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Here is a picture of a fuel cap vent for an SW. It does not change any fuel feed properties, but it does keep any fuel from sloshing out when full.

 

https://picasaweb.google.com/116835195307984673307/CTFlierFuelCapVentsAndWingHoseAccess

 

 

Here are two more pictures of holes drill to access the rubber hose for the fuel tank outlet fitting up by the fuel sight tube. Notice the fuel injection clamp with an Allen head. This makes life easy for whom ever needs to get back in here for the life of the plane. Done with a Dremel tool. Also notice the white air hoses on the bottom of the hole. I protect these with the blade of a putty knife while grinding out the hole.

When done just use a piece of Bolus tape over the hole like the wing root tape.

 

Pics were not viewable.

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Like many, I've had uneven fuel tank usage.  The left tank has consistently used more.  My fuel vents are always placed forward and the green dot is in the correct place related to the higher part of the cap skirt. 

 

Part of my preflight includes blowing through the fuel vents to make sure there is air passage when I'm checking the gas level (fuel caps off). The amount of blowing pressure has felt about the same.   Recently, I reversed my routine and sucked a small amount of air through the vent caps and noticed a small difference in air flow under a low pressure draw.  For the heck of it, I switched the vent tubes on the wings.  Now the right tank uses more fuel.  I'm guessing at low pressure fuel draw, there is enough of a difference in fuel vent air passage to result in uneven gas flow. 

 

Does anyone know if the tops of the vent caps can be removed to visually check the vent hole?  I don't want to force anything here.

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