Alcohol resistant fiberglass wing tanks for Kitfox IV

[DesertFox4]

I type too slow. Below is my response which says the same thing as Av8r3400. Only thing Av8r3400 beat me to the post. Oh well. I'm posting anyway as it represents 10 minutes of work that I don't want to delete.

What about someone making tanks out of METAL?

Skot- many a thread has been dedicated to the "why not aluminum tanks" subject here and on several other Kitfox/Avid sites as a cure for the alcohol problem associated with older fiberglass tanks.

Problem is. They don't work. Many have tried all the way back to the early Avid and Kitfox models.

The fuel tanks are a structural element of the Kitfox wing. They are glued to both the front and rear spars. The fiberglass tanks will bend/give with the flexing inherent in our wing design. No problems. No leaks, usually.
Aluminum tanks will not accept the continuous bending loads induced during flight and will break at the welds leaking fuel into the wing. Not a desirable situation which results in much time and labor to replace the aluminum tanks.

[SWeidemann]

Okay, I get it. My vision was narrowed by my Luscombe with metal wing tanks however that wing structure can get along with or without the tanks inside. The air loads are handled my the spars and the stressed skins around it. The tanks are strapped inside. I do understand that to change out the wing tanks on a Kitfox is a major job. In my Rotax class the instructor told us to seek out premium auto gas without ethanol however there is a "Thirty Day Rule" for auto gas (with or without ethanol) for auto fuel going bad and causing problems with lots of components not including the fiberglass fuel tanks. Yesterday a Lockwood staffer told me it was best for the fiberglass tanks to run Avgas. At any rate I think I will drain my tanks (of premium no ethanol auto gas) this week since the plane will be down for repairs most likely more than 30 days. Thanks folks for your info.

Skot

[tommg13780]

The ethanol can be removed from the gas. It's not a difficult process but somewhat time consuming. I "washed" about 300-400 gallons to avoid damage to my Kitfox II fiberglass tanks for a season. If someone is interested I can detail the process.

[jdmcbean]

The ethanol resistant tanks were not available until 2008 and they are serial numbered in the inboard side. You cannot tell by color.

Ethanol is not the only issue.. Acetone and Toluene are both products in AutoGas that will also effect down stream.

[n61kf]

Here are some pictures of my mid 90's tanks from my model IV. I replaced these last winter with newer tanks. The old tanks never leaked, and I did not experience any fuel contamination problems. I became aware of the problem when there became a noticeable buldge in the bottom of the wing. The resin bonding the baffels to the shell of the tank disintigrated, allowing the bottom of the tank to buldge downward due to the weight of the fuel. These old tanks were sloshed with Hirsch tank sealer. The shell of the tank appeared to be unaffected by the ethanol, just the bonding resin.

Keith
IV-1200 /912
Waynesville, Ohio

[n61kf]

Dave, the debris in the tank is chunks of the resin used to bond the baffels to the top and bottom of the tank. It did not disolve, it just disintegrated into chunks. When I removed the wings and tiped them it sounded like they were full of gravel.

Keith

[Allan]

My tanks were replace 2010 and the new ones did the samething in less than 3 years there is a problem with wing tanks

[DanB]

My tanks were replace 2010 and the new ones did the samething in less than 3 years there is a problem with wing tanks

It's more than just saying there is a problem with the wing tanks...much testing went into the development of the newer wing tanks. The problem lies in the fuel industry and their inconsistency in the additives from one area of the country to another. Bottom line...it is safer to use 100LL with a lead scavenger (such as Decalin). This is what all of us in the Desert Fox Squadron do instead of playing Russian Roulette between different Station fuel purchases. We all know to do so will require a bit more maintenance for the engine / gearbox a ways down the road...but it is better to anticipate that future (somewhat controlled) issue rather than worry about a leak in our tanks.

[beeryboats]

Dan, can you expand on your comment about more maintenance from using Avgas? I just bought a IV that has been stored for ten years and was told it ran on auto fuel only. That stuff scares me to death.

It's a '93 model so I assume it has the old tanks. Any tips from the crowd as to what I should do concerning the tanks? Also, what's the best fuel line to use? I'm changing out anything rubber on the aircraft.
Jay

[ackselle]

Read through this link..... It might help explain some of the extra maintenance needed if avgas is not treated properly. I replaced the rings on my 912, which were gummed up because the previous owner did not use decalin with his avgas.

Since I've run with mogas....everything stays clean.

http://www.teamkitfox.com/Forums/sho...ighlight=Rings