Fuel tank question/issue

[Jerrytex]

Anyone know if you can tell whether or not the fiberglass fuel tanks are made with the Vinyl ester or the polyester resin? Maybe somekind of test to tell the material composition? Mine are from a 1994 kit and Kitfox suggests sloshing but then I read the horror strories about it coming off in flight and plugging up the fuel system. (even if the the tanks are prepared correctly) If they are made with the Vinyl ester , I am thinking about just going for it and using the ethanol gas and monitoring the tanks. Maybe emptying them after each flight so the gas doesn't sit. I believe there is one gentleman on this forum that has been using Ethanol gas and has had zero problems.

If they are the polyester ones than:

I thought about just running 100LL with decalin and dealing with the lead in my 912. This seems like the cheapest route short term but after speaking to Lockwood Aviation, I would definately be in for an engine cleaning in the near future. Who knows how much that'll cost and they recommend using the ethanol fuel for other reasons.

I thought about changing the tanks but that is very costly. I just fininshed the wings. Now I would have to tear back into them. What a drag! Not to mention my budget is already stretched to the max. That is why I bought a USED kit.

The plastic wing tanks are as much or more than replacing them with factory tanks so they are not really an option. I would require 4 tanks to get close to the 26 gal capacity I have now at $525 per wing. (although probably the easiest and the most "Ethanol proof")

I can weld aluminum so I thought about welding up some tanks and doing kind of what the Wingtanks.com plastic tanks do, only alot cheaper. Since they would be foamed in and not part of the wing structure, there would be no stress thus no leaking seams. This would require alot of "engineering" on my part.

It seems like one day there will be no lead in avgas so that will cure alot of the problems but I am sure that is many years away and I want to fly now. Anyone have any other suggestions? How is everyone else dealing with this? I know it has been cussed and discussed many times on several forums but there really doesn't seem to be concensus on how to deal with this.

[DesertFox4]

Lots of questions in one post but I'll just address the 100LL option with Decalin. That is what I run 100% and I use the Decalin from Kitfox Aircraft with no issues after 750 hours of use in my 912S powered model 4. I've seen no indication of lead build up yet and spark plugs come out perfect after 100 to 150 hours. No performance issues either. Using the Decalin religiously is the key. Also changing oil every 25 hours if possible. I choose to also change the filter and clean out the oil tank at every oil change. Usually a little lead found at the bottom of the oil tank.
This is the easiest solution to your concerns then sloshing the fuel tanks followed by replacement.

[baronecozza]

Hi,I'm Marco from Italy, new forum user

I'd like to tell about a safety related problem I had with Fyberglass tanks.
I'm the owner of a model III and I decided to install a new pair of wings, the speedster ones with the new ethanol resistant fiberglass tank to improve my endurance.
Before installing the tanks I called John from kitfox aircraft to ask if the tanks were needed to be treated because I noticed a considerable amount of residual fiberglass inside.
He told that no treatment is required for this kind of tanks, but I had to rinse them before installation.
I did it twice, shaking strongly with unleaded fuel, the one we have on italian market.
After 3 hours flying I started to have problems.
At the first start attempt engine run on 3 cylinders only.After a short warm up It was running normally as well as in flight.
The problem appeared 3 times, always at the first start up so I decided to ground the aircraft to inspect.They found 3 intake valves stucked due to resin melted in the fuel.Fuel filters were ok but all the fuel system, carburator and cylinder heads were contaminated.I drained some fuel from gascolator and I let to evaporate under the sun:the residue was an huge amount of sticky and pasty material.I disinstalled the wings and I rinsed again the tanks but more I rinsed more I had residue.I solve the problem treating the tanks with tankerite (www.tankerite.com (http://www.tankerite.com)) with all the difficulties you can imagine and cleaning all the engine.I paid 3700 euros for all these jobs.I obviously notified everythink to John but He has still the opinion that I did not rinse the tanks.
If someone wants to see the pictures I'll send them by email.
I hope this topics could be useful, first of all for the european owners.
Sorry for my english
Marco

[HansLab]

Hi, I definitely would like to see your pics. I'm not at the point yet that I have to encounter your kind of problems, but I bought a project with installed tanks (How on Earth do I know which year/type they are?!?!?!), and have no other opportunaties than to either tear the tanks out, or follow your way...
Looking forward!
Hans

[cap01]

marco, thats a real horror story . there have been other problems with fibers noted on this forum . now youve got me concerned . i replaced one tank last winter and have over a hundred hours on it with no problems . i am planning on replacing the other tank this fall/winter . so , to seal or not to seal ? would be interesting to read about the seal you used but its not in english .

[ofergd]

If you can weld aluminum I would sugest make the engineering necessary and make aluminum tanks. From my experiance, (in other airplanes) properly designed aluminum tanks are trouble free for a very long time.
You can copy the original KF design or the wingtanks.com design an make it out of aluminum and you can use any fuel on the market.

Ofer
KF-II
Jab 2200

[Andrew G]

I was in the marine gas tank business for a short time... I've been reading with interest about the Kitfox gas tank issues for a while now... My suggestion to the Kitfox owners is to contact a Rotomolder to build Kitfox gas tanks.

Rotomolding is a simple process, powdered plastic (Cross linked poly) is dumped into a mold and then spun in an oven. As the powder melts into a liquid, the liquid plastic spins onto the inside of the cavity... the cavity is cooled and viola' - a gas tank is made with NO fibers...

The marine industry has suffered immeasurable harm due to ethanol related issues... hurting both aluminum tanks (the coating inside was "melted" by ethanol) and of course good old fiber-built tanks.

Unlike molds used to make plastic injected plastic products, Roto molds are relatively cheap to make, and if the orders pattern is decent, the roto mold companies will build the cost of the mold into the piece price. Roto mold companies are used to making short runs, i.e. 100 pieces is acceptable and not outrageously expensive.

Roto molded, cross linked poly tanks are tough as nails and light.

Just a suggestion as it looks to me that the fiber-based product produces a possible negative variable in the flying equation. Would go a long way for peace of mind.

[Peteohms]

Girley Men stop reading here. Not for the faint of heart.

I have been "washing" my gasahol to eliminate the ethanol successfully now for nearly 3 months. In 3 months I've used probably 90 gallons of washed gas with no problems.

I use a 6.5 gallon glass carboy. Into the carboy I put 1 qt of water and 5 gallons of 93 octane gasoline with ethanol. The 2 are mixed by putting the water in first and then siphoning the gasoline out of my 5 gallon gas can with the siphon hose going into the layer of water and bubbling through it. Actually the hose starts the water/gasoline swirling in the bottle. After 30 minutes I siphon off the gasoline leaving about a gallon of gas floating on top of the water/ethanol mixture.

I then siphon another 5 gallons into the gas/ethanol mix at the bottom and keep going for another few times. When I get 4-5 inches or gas/ethanol at the bottom of the bottle I start a siphon at the bottom and siphon the water/ethanol mixture out of the bottom of the bottle and start again.

Throughout the process I leave the same inch or so of gas floating on the water/ethanol so I never waste gas only alcohol.

Flame away girley men!

Pete
Kitfox III SN 1000, 912

[Av8r3400]

What do you figure the octane rating of what you have after this "washing" process is? Have you ever checked it or how?

[Peteohms]

Haven't checked it. I have an older 912 low compression so 87 would be fine. No problems at shut down. Others have sugested I might loose 5 octane points.


Pete

[DesertFox4]

OFERGD- Aluminum tanks were used in the early Kitfox's with poor results. Since the tanks are bonded to the spars it flexes with the spars and the welded seems give up and leaks are the result.

[baronecozza]

Hi, I definitely would like to see your pics. I'm not at the point yet that I have to encounter your kind of problems, but I bought a project with installed tanks (How on Earth do I know which year/type they are?!?!?!), and have no other opportunaties than to either tear the tanks out, or follow your way...
Looking forward!
Hans

Hi Hans, let me know your email address in order to send the pictures.
Ciao
Marco

[baronecozza]

marco, thats a real horror story . there have been other problems with fibers noted on this forum . now youve got me concerned . i replaced one tank last winter and have over a hundred hours on it with no problems . i am planning on replacing the other tank this fall/winter . so , to seal or not to seal ? would be interesting to read about the seal you used but its not in english .

Hi,
here below the translation of the Tankerite characteristics.I know that 3M has a similar product to treat the tanks.
This is a permanent cycle corrosion protection for the remediation of internal ammalorati rusted and tanks, which form a capsule sealant, resistant to petrol, alcohol and fuels. Finally, here is the optimal solution to prevent and stop rust internal tanks cars and Motocycles, avoiding costly replacements as often unobtainable.
Our repair kit consists of three products, is easy to use, and is then available to anyone who wants to ensure economic and solving this problem permanently.
Operating instructions are clear and the result is professional.
The inner surface of the tank is coated with a resin corrosion, sealant and ceramic high and solid appearance. It is however at the same time extremely elastic, so as to form a capsule vibration-proof sealant and thermal stress of exercise (designed to withstand temperatures from-30 ° to + 120 ° C).
Porosity, crackles and sheet metal are therefore assottigliamenti wetlands permanently. To know more, consult also our FAQ.

[ofergd]

Steve
The tanks shouldn't be welded to the spars, just like tha fiberglass ones are bonded with an elastic bond. Similar design can be applied to the insallation of aluminum tanks. The tank I designed for a diferant plane is made of 0.1" 5052 aluminum and has internal semi ribs for strength so it can stand alone. It is straped down and not bonded to the spars.

[DesertFox4]

none of the failed aluminum tanks were welded in place only bonded like the fiberglass.

[Av8r3400]

Steve
The tanks shouldn't be welded to the spars, just like tha fiberglass ones are bonded with an elastic bond. Similar design can be applied to the insallation of aluminum tanks. The tank I designed for a diferant plane is made of 0.1" 5052 aluminum and has internal semi ribs for strength so it can stand alone. It is straped down and not bonded to the spars.

.1" thick?! That thing must have weighed a ton!

[Jerrytex]

My thoughts on the aluminum tanks were to make them like the poly wing tanks that just drop in to the existing fiberglass tanks. Then foam them in. This way they would not be structural and I would not have to worry about cracking. I would like to find an old Kitfox tank that I could use to make my prototype rather than cut my existing ones and find out that I cant' make them fit.

I will look into the Rotomolding as well. Also after hearing that "washed" gas is working, that might be a viable option as well. Another person I was reading about is doing it with good results too. I would be a pain but worth it if it works.

[Av8r3400]

I will look into the Rotomolding as well.


Buying them from WINGTANKS.COM (http://wingtanks.com/) would be considerably easier and cheaper than tooling up a one off, redundant, roto-mold run.

[Andrew G]

yeah, that aftermarket solution looks good... those are "cross-linked poly" tanks, which is what you want from a product perspective. That's what they build in the marine business... I can't quite understand the installation, but you K'fox builders probably understand it.

Perhaps one day, the factory will commission two molds (left and right) and sell these tanks as part of the kit... ethanol isn't going away, I hear it's going to get worse... and those fibers scare the heck out of me.

Andrew

[mclayton]

For what it is worth....

I am rebuilding a Kitfox II, which came with aluminum fuel tanks. There is no evidence of leakage, and all the welds look solid. The manual calls for the riveting of the aft end of the tank to the spar with five rivets. Mine only had two rivets. As I rebuild the wings, I plan to reuse the aluminum tanks, but will try to cushion them between the spars with some elastomeric material, and may also consider trying to come up with some strapping arrangement, which seems to be the more standard method of installing fuel tanks. Using rivets seems to me to be asking for trouble, as the wings do flex in flight.

[avidflyer]

There is a guy in Corona Ca that has a set of fiberglass wing tanks for a Kitfox 3 for sale. I think he had them on Barnstormers. He is parting out his Kitfox 3 so is running a number of adds for Kitfox stuff. If you don't see the tank add, you can get his phone # from one of the other adds. Take care, Jim Chuk

[Jerrytex]

Pete

I was just checking to see how the ethanol washing is going. I noticed more people are doing it now. There is a company, I think it portable fuel systems that is working on a retail unit that washes the gas. I spoke to a local fuel distributor and he said that they train their new employees about washing gas. He said it is to show them how moisture effects gas. He also said that removing the ethanol will lower the octane about 4 points so it seems that is the consenus. I believe this is the route I'll be going too.

[kitfoxnick]

Be wary of the wingtank.com tanks. I have installed both the crosslink poly tank and the new kitfox tank. The poly tank which come one per bay total of four utilize a push in rubber grommet fitting that is prone to leaking. In order to do the 12 gal per wing you need to connect the two tanks together, requiring six push fittings and installing another rib. I installed the tanks and less than 20 hours I had a leak. I looked into trying to thread fittings but the material isn't thick enough and you can not weld crosslink poly. I elected to remove and install the new kitfox tanks. These tanks are a great fit light weight and no mechanical fittings in the wing. If anyone wants a set of poly tanks let me know I'll be glad to recoup whatever I can.

[Peteohms]

Pete

I was just checking to see how the ethanol washing is going. I noticed more people are doing it now. There is a company, I think it portable fuel systems that is working on a retail unit that washes the gas. I spoke to a local fuel distributor and he said that they train their new employees about washing gas. He said it is to show them how moisture effects gas. He also said that removing the ethanol will lower the octane about 4 points so it seems that is the consenus. I believe this is the route I'll be going too.

Jerry, I put 100LL in last fill up as the plane is sitting quite a bit lately. Weather, projects and family stuff have conspired to keep me grounded more. I did not want to have mogas sitting in my tank for long periods of time. I found that when I sumped my plane once the weather turned cool that I got a few ounces of water/ethanol settling after a week or so sitting. Never had an engine problem though.