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) 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