Header tank relocation

[Deejayel 1]

Today I "upgraded" my original header tank to a new one. My build manual directs me to secure the tank on the structure where the shoulder belts are secured. So its way back toward the rear of the turtledeck. I've seen pictures of other installations and I think the 5,6and 7 have it located just behind the seat. So thats where I installed it today. It was a nice clean install and the fuel hose routing down the cross tubing cleaned up my hat rack.

I did notice due to the "elevation" change, the fuel does not flow as fast from the tank out the gascolator. Is there a minimum flow rate, or will the mikuni pump sufficiently pull all thats required? I dont have a standby electric pump installed at this point. I parked her on a hill, shut off both wing tanks and ran her at 5500 rpm for 10 minutes or so and didnt notice any difference as the fuel level in the header was depleting.

[C5Engineer 1170]

Looks nice! I seen someone was selling one of these for like $45 the other day I thought about grabbing it but I don't need anymore projects for the plane right now.

[akflyer 1427]

Mine is in the same location and last time home I drained the tanks to change out all gas lines and to reseal all those damn fittings on the header tank.  I took the line off at the fuel pump and ran it into the 6 gallon cans just using gravity.  It was flowing at 15 GPH as shown on the fuel flow meter and that worked out as I timed the filling of the cans.  I would not think twice about having your header where it is.

 

What did your seal the tank to bushing threads with?  I fought mine for 3 yrs always having the slightest of gas weeps, but the smell was always there.  I just cleaned them up and sealed them with the permatex aviation gasket sealant and for the first time ever, I don't smell gas in the cockpit.

 

 

[tcj 150]

According to the Rotax two stroke installation manual the pulse pump will pull the required amount of fuel if the fuel tank is not mounted "Considerably lower than the engine".  The only place I have been able to find what distance  "Considerably lower" is, is in this document which says "more than a meter".   http://www.lightaircraftassociation.co.uk/engineering/Mogas/Rotax%202/Inspection%20Checklist%20-%20Rotax%202%20Strokes.pdf

 

When doing my fuel flow tests, I tested the gravity flow rate at the outlet port of the gascolator.  The minimum flow standard for gravity fuel systems is 150% of engine full power fuel consumption.  For pressurized fuel systems its at least 125%.  I had more than 150% so didn't worry about trying to figure out how to test the pressure flow rate out of a pulse pump.    

[Deejayel 1]

Sounds good. Thanks. The flow certainly increased when I lifted the tail up to level flight

The picture I posted was from the first install. As with everything I do, its usually "third time's the charm". So after filling the tank the first time with all the plugs in place, I was getting some seepage from a few fittings. I went to ace and got some thread compound. Looks like toothpaste. Designed to be used on fuel fitting applications. By the time I left the bird last night there was no evidence of leakage. When I go out this afternoon....hmmm we shall see

The new tank has 7 ports where my old one had only 4. The picture shows my main fuel line from the tank at the very bottom. But on my second install attempt installed a fuel drain valve. There is another port about an inch up where I then installed the main line. Of course the three on top where the same. 2 tanks aand 1 vent. And on the upper side there are two more ports presumably for a fuel level sensor of some sort. Not sure.

I'll get some more pictures posted this evening of the install.

If anyone wants my old tank, you are welcome to it.

Edited 20 Oct 2013 by Deejayel

[akflyer 1427]

I have the same tank as you.... good luck on the hardware store paste.. its made for gas line, as in natural gas.  If she is leaking, go to the local auto parts store and grab a can of the Permatex Aviation Gasket sealer.  It did the trick for me when the normal fuel lube and what ever paste that KF factory used failed.

 

Yours is plumbed the way I have mine too, except I dont have a vent.  The header tank will vent to the lowest fuel level in the opposite tank through the normal gas line, and once its full, there is no need to vent it any more.

 

 

[EDMO 1078]

Leni,

I copied from the Kitfox catalog, Permatex 9AR, part # 64195 - and my auto parts store could not find it in their catalog. Wonder if there is a comparable Loctite product?

EDMO

[Deejayel 1]

Yep. That paste didnt work. So I will find the permatex. I did get 2 hours in today with my cub buddy before I started to get queasy with the fuel smell.

I use the clear vent line as a fuel level gauge for the header tank. If the line is empty, I had better find some gas.

Now that I have a spare tank, I'm going to carry it to some fab shops and see if an aluminum one can be made easily(read inexpensive)

Edited 20 Oct 2013 by Deejayel

[SkyPirate 8]

If you can , use 3003 aluminum it is less suseptible to oxidation from exposure to fuel, some use 6061 like zenith aircraft does for the "D" tanks in the leading edge of the wing, 3003 you can make a fuel tank and not weld it at all, using tank sealer at folded joints and compression fittings and bolt on filler tube, advantage no welded seams to crack, but 3003 can be welded also and take vibration and flexing better then 6061

[Deejayel 1]

Nice Thanks. 3003...

 

In the meantime to get me running again, Akflyer: "Permatex aviation Form a Gasket Sealant 80017(3D) or 80019(3H)

Edited 20 Oct 2013 by Deejayel

[akflyer 1427]

either one, they are both the same stuff, just one is in a 4 oz bottle the other is 16 oz bottle.  I took all the brass bushings out of the tank, and put the hose barbs into the brass bushings using the sealer, then screwed the assembly into the tank.  Be careful threading them into the tank as the plastic threads will pull pretty easy.  With the gasket sealer on the threads it does not need to go into the tank much more than hand tight, just good and snug.  Let it set over night before you put the gas to it.  The sealer will thicken and stifffen up quite a bit, but it wont harden all the way.

 

[Deejayel 1]

Perfect. Thanks.

[C5Engineer 1170]

I was told to buy this stuff from Spruce/CPS for sealing fuel fittings.

 

http://www.cps-parts.com/catalog/cspages/ezturnlube.php

[akflyer 1427]

that is what I used the first time.  It may work good for metal to metal connections, but it dont last long in the plastic header tank.. I tried to reseal with that stuff several times and it always weeped through after a few days.

 

[Deejayel 1]

Got all the fittings sealed. That stuff is like molasses.

Edited 23 Oct 2013 by Deejayel

[Deejayel 1]

Well, that didn't work for me. All fittings were leaking. The fuel was definitely softening the permatex. Blast. Now what?

[Deejayel 1]

I'm going to try the Permatex tack and seal gasket sealer tomr....

[Deejayel 1]

No leaks!! Couldnt find the "tack and seal", so went with Permatex #97 high tack. Finally....

[SuberAvid 617]

Looks nice but I have never had any problem with the original aluminum tube header tank in my Avid/Avid+ and would be in the way in my Avid+.  What is the reason to "upgrade" to this?  Does it just hold a little more gas?