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Wing Tank Install

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Posted (edited)

Does anyone have a procedure for:

Installing a new wing tank in a wing that never had one

Replacing an existing wing tank.

 

Thanks,

Robb

Edited by Knuckledragger

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Posted (edited)

Kitfox used a  GE II silicone caulk to anchor the fiberglass tanks to the spars - I started with a box knife, cutting as much of the sealer away as I could reach, sometimes being able to tear the tank from the spars, and other times having to finish cutting with a hacksaw blade, and using a heat gun to soften the 9460 used to glue the wood dowels to the tank which are used to brace the root rib.

To install a tank in a wing that never had one, you have to remove the part of a rib that is between the spars - maybe 2 if you have HH wings.  You also have to relocate or remove a drag brace or two, and remove angle braces from the root rib.  These will be replaced by wood dowels or blocks in about 4 places to brace the root rib against the side of the tank to keep the fabric from bending it.   Top and bottom parts of the ribs you removed may be used to glue them to the tank for the fabric to attach to.

If I have forgotten anything, then you can ask, or someone can add to this.

EDMO

Edited by EDMO

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Posted

I used steel piano wire with a wood block on each end to cut the silicone.  Worked slick as snot to cut out the old ones out with no damage to the spars. 

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Posted (edited)

I used steel piano wire with a wood block on each end to cut the silicone.  Worked slick as snot to cut out the old ones out with no damage to the spars. 

Good idea Larry - I should have said that my hacksaw blade was an old, worn-out one, with the teeth ground off smooth on each side to keep from scratching the spars.  I clamped a pair of vise-grips on each end for handles.

EDMO

Edited by EDMO

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Posted

Does anyone have a procedure for:

Installing a new wing tank in a wing that never had one

Replacing an existing wing tank.

 

Hi Knucledragger,
I installed a tank in my left wing 2007 an succeeded to dig up a paper copy of the mail with instructions I got from Steve Winder. Put it through a text recognition program on my iPad...
 
After a few initial mails to confirm the exact wing, confirmed to be a "true heavy hauler" we get to the actual instructions (if your wing is not a true heavy hauler you might need to change the procedure slightly):
 
1st Leak check the gas tank. Put about 10 liters of fuel in the tank and Stand it on end. 
Roll it around to see if it leaks. 
If you do find a leak. Clean around the area and fill/coat with some of the structural adhesive / epoxy.  If No leaks then ready to proceed. 
ONE VERY IMPORTANT THING. 
YOU MUST INSTALL THE TANK WITH THE WING ON THE AIRPLANE. OTHERWISE 
YOU WON"T GET THE ATTACH BOLTS IN.
 
What you have to do is Remove THE DRAG TUBE, THE First 6 nose ribs AND the First 4 ribs. 
But ONLY remove THE PIECES OF ribs BETWEEN THE FRONT AND REAR SPAR. 
I.e. Leave the Trailing edge of the ribs from the rear spar to trailing edge, attached 
to the spar. AND you must leave about 4" of the Top and Bottom Capstrip FORWARD of the Rear spar in place. 
(I have found that Hacksawing the Ribs close to front spar and about 4" in FRONT of 
the rear spar works. Can then use a Heat gun and HEAT the ribs at the Front spar—will 
break away very cleanly.  Use the hacksaw to remove the 4" piece of Rear Spar Rib BETWEEN the capstrip) 
These Pieces of Top and bottom capstrip attach/glue down into the SLOTS of the new gas tank. 
You will also need some fiberglass Mat (2 pcs 40" x 30 " ) and Fiberglass Cloth (2pcs 
40" x 30") AND about 1 litre of Polyester Fiberglass Resin with Hardener. 
When you have removed the rib material between the spars you slide the gas tank between the spars to check fit etc. 
With Wing Folded, Put Glue on spars and tanks and slide in place. 
Put wing in place and put Front pin in. 
Align the wing tank with Trailing edge pieces of ribs and capstrips. 
Clamp wing spars to tank and leave to set. 
CLAMP andGlue the capstrips down to the Notches in the top / bottom of tank. 
When everything has glued and set up you WRAP the tank with the Mat and then the cloth. 
This "locks" the tank in place and puts the strength back. 
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Posted (edited)

I used steel piano wire with a wood block on each end to cut the silicone.  Worked slick as snot to cut out the old ones out with no damage to the spars. 

Like removing an old windshield! :BC:

 

Thanks for the great write up FredStork!

Edited by Knuckledragger

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Posted

Wow - That Avid procedure is a lot more work than Kitfox tanks!

EDMO

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Posted (edited)

I called Kitfox today.  They said the airfoils are different enough that their tank wont work in my speedwing.  I'm running out of ideas here....:(

I'm pulling my hair out trying to figure out what to do about my leaking tank.  The leak is on top of the wing.  It just showed up as a pinhole in the fabric about 1/3 of the way back from the leading edge.  Prior to seeing the stain that formed on the fabric, I noticed that I was using 5-6 gals of fuel per hour.  I imagine that the fuel is being vented out by the low pressure air flowing over the wing.

Edited by Knuckledragger

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Posted

I called Kitfox today.  They said the airfoils are different enough that their tank wont work in my speedwing.  I'm running out of ideas here....:(

Rob,

How urgent is your need for a tank?  I'm probably going to make a new one for mine when I get it deconstructed for refurb (new fabric, repaint the frame, make float rigging, maybe wider main gear and a matco tailwheel since the consensus seems to be those two make it an acceptable taildragger).  My tank has brown sludge in it, which is usually an early indicator of decay.  It might just be the MTBE from the car gas the California builders ran in it before ethanol was mandated there, but I'm not entirely sure.

If you have the old tank as a model to work from, we could make it a twofer while I've got the foam, hotwire saw, epoxy and glass work going.

Mark

Does anyone have a procedure for:

Installing a new wing tank in a wing that never had one

Replacing an existing wing tank.

 

Thanks,

Robb

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Posted

Does anyone know what kind of Resin system was used on the wing tanks originally?  Was it Epoxy, VinylEster, Polyester, etc?

Mark

 

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Posted

Polyester resin for both the Avid and Kitfox on the early tanks and then vinyl ester in the later tanks that came with the KF's.

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Posted

I just read on the EAA forums, guys with similar wing top pin hole issues came with this solution:  Use a carefully applied vacuum source to put negative pressure inside the tank while allowing resin to be sucked back into the hole.  It will find its way into the leak and seal it.  Hmmm...

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Posted

Big thanks to Chris Bolkan and Mark Sires for spending time with me on the phone today!

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Posted

I just read on the EAA forums, guys with similar wing top pin hole issues came with this solution:  Use a carefully applied vacuum source to put negative pressure inside the tank while allowing resin to be sucked back into the hole.  It will find its way into the leak and seal it.  Hmmm...

Just make sure it is a very small vacuum source - the tanks are designed for negative pressure, and it doesn't take much to collapse them.

Mark

 

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Posted

Polyester resin for both the Avid and Kitfox on the early tanks and then vinyl ester in the later tanks that came with the KF's.

Thanks! that is good information!

Mark

 

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Posted (edited)

I called Kitfox today.  They said the airfoils are different enough that their tank wont work in my speedwing.  I'm running out of ideas here....:(

I'm pulling my hair out trying to figure out what to do about my leaking tank.  The leak is on top of the wing.  It just showed up as a pinhole in the fabric about 1/3 of the way back from the leading edge.  Prior to seeing the stain that formed on the fabric, I noticed that I was using 5-6 gals of fuel per hour.  I imagine that the fuel is being vented out by the low pressure air flowing over the wing.

if you know exactly where it leaks, go for a repair, if it was mine, i would go to make a little patch with polyester resin and microballoon 

Edited by efil 01

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Posted

If it is small enough hole, I wouldn't even bother with micro - pure resin/hardener will seal it better, and it isn't big enough for the weight to make a difference.  Micro gives the opportunity for more pinholes to form.  If too big for pure resin/hardener, I'd go with Flox over micro, then coat it again with pure resin/hardener after the flox cured.

 

Too bad they used polyester resins, it is the least resistant to chemicals of the three major options, but it is also the least expensive, and most commonly used (boats/surfboards).

Mark

 

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