Vasaline like goo in my fuel filter

[Wheels]

Hi,
I parked my kit fox model IV 1200 Rotax 912 80 horse to do some maintenance on the water system and inspect what appeared to be ice in the bottom of the glass filters from the wing tanks.

I took the glass filters out and removed the elements. There is a grey vasaline -like substance in the bottom. No evidence that it has made it downstream in any volume but I'm not sure what this is. The tanks are bran new ethanol resistant and have had about 150 gallons through them since install. I don't know what the mechanic used to clean them prior to install and I think he's dead now anyway. If he used any kind of sealant to insert fittings, it would have been fuel resistant and I can't imagine it ending up in my filter. I'll pull the gascolator filter next. I want to see whats in that.
Any ideas as to what causes such a gooey mess in a filter element?

[Av8r3400]

This *may* be the BSS (brown sticky shi-stuff - the release agent from the new tanks) before it turns brown.

It is very, very imperative that new tanks are rinsed out thoroughly and repeatedly with acetone to remove this material. Gasoline (aviation or auto), lacquer thinner, ethanol, soapy water, harsh language, whatever - won't take it out.

See Service Bulletin SB60. (http://www.kitfoxaircraft.com/support/service_bulletins/sb60.pdf)

[Flybyjim]

Is this the case for the new SS7 kits?

[Paul Z]

I have a 7 SS, I have had the sticky stuff problem. It takes some tome and money but easier now than when in a plane!

[Wheels]

The mech told me that he had rinsed out the tanks thoroughly, hmm I fired him a while back,(no, he's not dead) looks like I'll have to rinse out the tanks. but he will stay fired.:p

[Av8r3400]

Is this the case for the new SS7 kits?

Absolutely. Definitely. Any tank made since 11-2007, with a serial number etched on it.

[Wheels]

Thanks Av8r300, I'm on it.

[Marvk7]

I've ran across this topic several times but have not seen instructions on how to clean the tanks. What's the best way to do this on tanks already installed ? Do you just fill and drain several times?

[TahoeTim]

yes, on the tank is a sticker with instructions

av8r is incorrect, it says to rinse with 50/50 acetone and auto gas

[Av8r3400]

av8r is incorrect, it says to rinse with 50/50 acetone and auto gas


I posted a link to SB60 (http://www.kitfoxaircraft.com/support/service_bulletins/sb60.pdf). Here it is again. Direct from Kitfox says acetone.

The 50/50 mix with avgas is to ease rinsing if you cannot remove the wings. If it were my plane and this material was found, I'd be pulling the wings to get as thorough a rinse as possible, using the straight acetone method.

[kitfoxnick]

Did this happen after you put gas containing ethanol in them. Did I mention that I like see through filters.

[Paul Z]

Yes I put in gasohol

[cgruby]

I have a type III with the non-ethanol allowed tanks. So far no problems. A couple of observations you're having with foreign material in the tanks.

1. I seems inconceivable that a female mold was used to make these tanks thus leaving mold release on the inside (how'd they get the mold out?)

2. and if they did, what irresponsible manufacturer would assemble a tank and leave goop on the inside??

3. KitFox should be able to tell us whether they used epoxy or poly-ester resine for these tanks.

4. in any event, I would clean these tanks the very best I could with a LOT of MEK, and then coat the inside with a couple of coat of epoxy resine. Epoxy is impervious to gas alcohol, or whatever.

5. Unless you want to remove the tank. I would cut a 1 foot square hole in the top to gain access to clean and coat. The hole could be covered by making a 1/2" flange and reinstalling the cover with nut plates or epoxying the top back into place.

6. If I was building a new airplane, I'd make this mod to the tanks before I installed them.

Stay warm,

[TahoeTim]

My response was to those in this thread that are still building. I should have clarified my response. It seems that there are two methods, one for new uninstalled tanks and another process if the tanks are installed. Or, the process has changed over the years.

I guess I will have to post a photo of the sticker on my new tanks, not yet installed, with the sticker still in place before you will believe me. It says 50/50 acetone and auto gas and NOT to use av gas. I have 10 gallons of old avgas that I would love to use to flush my tanks.

I will go to the hanger and post the photo. If I can't read English and have it backwards, I will eat crow.

[Dorsal]

I rinsed after my tanks were installed by taking the wings off, poring in 1/2 gallon of acetone, sloshing, draining and repeating til the contents ran clear. This was a two person job and took 1/2 a day, >400 hrs later and running great.

This is my story
http://www.teamkitfox.com/Forums/showthread.php?t=1557

[Slyfox]

take the cap off the tanks and put your fingers inside the tank and feel if it's soft or stuff comes off on your fingers, if so, tanks are bad for alki.

[kitfoxnick]

I had the brown goo after rinsing well with acetone. I filled my tanks with ethanol gas and they sat about a week. I noticed the brown goo so, I drained my tanks and have never had a problem since. Ethonal is a pretty good solvent my theory is the ethanol cleaned the rest of the contaminate (mold release, pva, i don't know what). Never had a problem since.

[Wheels]

No ethonol fuel in my plane since the tanks went in. I pulled the gascolator and it is absolutely clean. The filters in the cockpit got the goo. Did I say I like those filters? I"ll flush with the wings on and post if there is any residual but I'm not afraid to fly it after the tanks are cleaned. Thanks for all the posts. Skis on tonight!

[Flybyjim]

what is the issue with the goo, I have built 3 experimental the last being a Rans S7--this was not an issue at all, What are the tanks made from on the Kitfox and is it a better material than the poly tanks from Rans?

[Av8r3400]

The Kitfox tanks are made of fiberglass. They need to be strong because they are structural to the wing.

Rans uses smaller roto-molded polyethylene tanks which are not integral to the wing structure.

[Flybyjim]

If their structural how are the mounted in the wing assembly

[TahoeTim]

+1

How can they be considered structural when they simply lay between the spars with a bead of caulk to keep them from flopping around?

[kitfoxnick]

+1

How can they be considered structural when they simply lay between the spars with a bead of caulk to keep them from flopping around?

If you have ever removed them you will agree that their is a structural component to them. It takes quite a lot of effort to remove them from the spars.

If you eliminate them from the wing assembly you have to install drag tubes.

[Slyfox]

when I changed my tanks out I put auto fuel with alki in it to clean out the tanks, yes I got some ukee stuff, but it was used to get the top layer off the inside. now my tanks work real good and I use alki fuel all the time. at first I checked the tanks like John said to, you put your fingers inside the tank and check for softness, stickiness, or anything unusual. there was nothing, after a few months I quit doing that. might be that your tanks needed to be rinsed inside. anyway that's my story.

[Slyfox]

one more thing. how do you know there is no alki in your gas. did you know if you take a sample of fuel and put a couple drops of food coloring in the sample you can test for it. if it mixes in the fuel it has alki. if it stays drops in the fuel it's not got alki.

[Av8r3400]

Great point, Sly. Often time you have no idea if you are getting ethanol contaminated fuel or not.

The food coloring test method is by far the easiest and surest way to test.

[jdmcbean]

Av8r3400 and TahoeTim are correct..
The rinsing instructions have changed and is labeled on any of the new tanks delivered. The Service Bulletin is still correct and should have been complied with by now.. Regardless we suspect there is a "blushing" that was causing the issue. We have taken steps to eliminate this issue at production but it is still important to rinse the tanks completely.
We found that with the additives in AutoGas allows for good cleaning.. Avgas does not have the additives and therefore is not a good cleaning agent for rinsing.. simply not as aggressive.
One caution: During rinsing be cautious of excess air build up. The Acetone during the first rinse will build pressure very quickly and can over-pressurize the tank if you're not careful.
Side note: many of the fuel sealants we have found from the 9AR to the Dow 730 products do not have great resistance to Ethanol.. Also, if too much is used it pushes inside the tank and into the fuel system.. This might be what Wheels is seeing in the filters.

[Kurt.A]

For checking ethanol quantity you take a measured cylinder with 10 equal divisions and put 1 division of water with the rest your fuel of choice. The water and ethanol mix causing a cloudy mixture in the bottom of the cylinder. Good way to estimate the true volume of ethanol in your fuel.

[SkyPirate]

I carry a small mayonnaise jar with a filed line on the side..fill it to the line with water then add suspect fuel.shake it up , let it set a few seconds.if there is any ethonanol it clings to the water molecules and it will show more water content above the filed mark