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ethanol based fuels

grubac

Member
Hey Guys

It being, that more and more fuels are popping up here and there with certain amounts of ethanol in them, I was just wondering if anyone knows of any good solutions for those who already have fiber-glass-based tanks (therefore non-metallic) in their wings.

Are there any quick solutions out there? (aside from just installing aluminum tanks).

Any suggestions would be appreciated.

thanks

Grubac
 
Grubac,

You might want to check some of the power boat forums. I remember reading that ethanol based fuels were responsible for damaging the fiberglass hulls on a number of boats when it first came out a few years back.

(Some boats use the hull as one side of the fiberglass fuel tanks and based on the resin used to construct them, ethanol may deteriorate the composites. From what I remember reading and I could be wrong here, the boats impacted were no longer seaworthy and had to be destroyed.)
 
Hey Guys

It being, that more and more fuels are popping up here and there with certain amounts of ethanol in them, I was just wondering if anyone knows of any good solutions for those who already have fiber-glass-based tanks (therefore non-metallic) in their wings.

Are there any quick solutions out there? (aside from just installing aluminum tanks).

Any suggestions would be appreciated.

thanks

Grubac

You can always use 100LL. Most of the boat place are now ethanol as well. The latest energy Act has ethanol usage requirements that increase each year with appropriate penalties. I think your best hope is the new 80 or 100 unleaded that is in the works.
 
Though I am far from an expert on the subject, I can certainly confirm problems with ethanol fuel damaging fiberglass marine fuel tanks. I am a boatbuilder from NJ(with required all marine fuel to be 10% ethanol minimum) and I have seen the effects. Marine applications are further handicapped by the fact that these fiberglass tank equipped boats tend to suffer from both of ethanols great weaknesses. Boats are typically around high humidity envoirnments ...obviously. Ethanol naturally attracts and accumulates water through vents, etc. but does not readily mix with the fuel. So water gets in the tanks, and stays seperated. The other major contributating factor is that most boats do not get run too often, allowing the ethanol to attract more water.

The other major issue is the ethanol in your fuel wants to break down the fiberglass resin itself. The water collecting issue is a logistical hurdle to deal with, and there are a good number of people out there who are flying on nothing but ethanol blended fuel(though mostly in planes with metal or polyethylene fuel tanks). But in your instance, the ethanol wants to destroy(soften/break down) the resin in your tanks (vinylester resin appears to be most ethanol resistant). The softened resin then gets pulled into your fuel lines ...and bad things happen.

http://www.boatus.com/seaworthy/fueltest.asp

I have heard mentions of special slosh coatings that people were trying in an effort to "seal" the ethanol from the tank resin iteslf, but I have not heard of any reliabe information that suggests that it works satisfactorily. One that comes to mind is KBS coatings. To be clear, I have NO first hand experience with this stuff so therefore I have no intention on recommending it in any way.

http://www.kbs-coatings.com/Gold-Standard-Tank-Sealer-Information-Instructions_ep_39-1.html

A quote from a KBS company rep regarding their product(on a boating forum):

"When it comes to prepping and sealing the inside of a tank, you MUST USE the prep products and use them correctly. Also, if a tank already has substantial damage from ethanol blended gasoline, the cleaning and drying process is critical. Fiberglass can be rather porous and will hold moisture and/or fuel residue. That's why you need to use the AquaKlean degreaser correctly and possibly multiple times to remove all the oily residue from the old fuel. Rinse completely and allow to dry thoroughly.
Proceed with the RustBlast which, although there is no rust in a fiberglass tank, adjusts the ph to a more acidic level. Just a quick slosh with the RustBlast, pour it out, then rinse thoroughly again with clear water.
Now again let the tank dry thoroughly, as you do not want to trap moisture under the sealer. Use a blow dryer or shop-vac on blower to keep the air moving inside the tank to help the drying process. We place the tank out in the sun, plug all inlets, and rubber band a piece of plastic wrap tightly over the largest outlet. If after a couple of hours, you see moisture forming under that plastic, you still have some drying to do.
When you're sure you're dry, stir up the sealer and pour it in the tank. Slosh it around being rather methodical as you want to be sure to coat the entire interior surface. Any exposed fiberglass can still be affected by the alcohol. Once you're sure you've coated everything, prop the tank up and allow any excess sealer to drain out. You do not want the sealer to puddle inside.
Now, allow the sealer to cure at least 3-4 days before adding fuel again. Heat does not cure the sealer any faster, and therefore placing the tank out in the hot sun will not help, and may in fact hamper the cure strength. Just let the open tank cure slowly.
This is not a one night project. Take your time and you'll get great, long lasting results.

These directions and more can be found at: www.kbs-coatings.com"


A bit more drastic, but I have seen a few boats cut an access hole in the tops of their tanks just large enough to insert heavy duty bladder tanks. This basically turns the fiberglass tank into a protective case for the self contained bladder tank. This is certainly not the ideal solution for an aircraft, but it apparently was considered worthwhile for a few folks who were looking at $50,000 plus to replace their huge built in fiberglass tanks on their 50+ footers.

If the option exists, and you have a fiberglass fuel tank(s) built into your aircraft, the safest bet would be to run 100LL only.

George
 
I have heard of caswell plating's product as well. Sadly, I've read a good number of complaints from people (boating and motorcycles) that have tried these products to find that they failed. I don't recall anyone complaining that the product itseft broke down, but rather the sealer lost adhesion to the fiberglass tank walls itself. The respective companies response seems to be that the prep work and coating process must be done extremely carefully, but if done correctly it will adhere well and stay that way. It seems of those that I have read of, if it's going to fail, it will fail right away(within weeks). In a boat or a motorcycle having your tank sealer come loose on you while running could be problematic, but in in an airplane:confused:? It is an unfortunate situation or sure.

Clearly, boaters have been pissed:

http://www.fishingbuddy.com/boat_owner_alleges_ethanol_damage_in_lawsuit

http://www.tcpalm.com/news/2009/jan/21/class-action-lawsuit-filed-florida-boaters-against/

http://www.saltwatersportsman.com/a...ed-over-boat-damage-caused-by-ethanol-in-fuel

George
 
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ethanol tankage

...could a boat guy switch, and put non-potable water in the old fuel tank, and put fuel in the polypropylene water tank? ....some creative plumbing, and presto.....smelly water in the head, and nice clean gas in the engine! :)

hmmm, perhaps were being fuelish here!
 
Hey guys

Thanks for the responses. If I didn't make it clear in my first post, I'm actually interested in hearing about possible solutions because I have some friends who have fibreglass tanks and they've been concerned about the possibility of tank degredation.

The BOATUS.com article is really interesting. Thanks George! It really does a good job of explaining how ethanol reacts with epoxy resins and what the consequences are.

The tank sealers don't seem like a 100% reliable solution. Like written, it's necessary to apply the tank sealer VERY carefully in order to achieve the desired results. One mess up and you're back to square one.

Correct if I'm wrong, but replacing the tanks with a metal-based tank looks like the only "sure" solution. Stuffing a fuel bladder into the fibreglass is a also an option.

Grubac
 
The Flight Design CT is a carbon fiber reinforced plastic airplane with integral fuel tanks. The factory uses a product call Kreem Weiss for internal coating of the fuel tanks and it works for that application. Google it.

I only know of one person who has had to redo his CT tanks. He seemed to think it was an easy enough application. The hardest part was rotating the wings to ensure an even coating in the tanks.

I don't know anything other than that about the product.
 
grubac,

No problem. Unfortunately, I have serious concerns regarding the process of sealing an intregral fiberglass tank(such as a wing tank) with an aftermarket sealer. The process ideally requires being able to turn the tank in every direction at will to carefully clean and seal all the surfaces. That is pretty easy to do with a 3 gallon motorcycle tank, but not so easy in a completed airframe! And certainly not feasible in a 40,000lb boat.

Personally, I'd have a very hard time considering the sealer method worth the risk for an aircraft. If using 100LL exclusively is a possibility, that would sure seem to be the prudent thing to do. I know there are outfits that will custom make bladder tanks to your specs. It may be worth looking into the plumbing/venting/cost issues and see if it may be a viable option.

A few things to look at:

http://www.atlinc.com/marine.html
http://www.fuelsafe.com/custom.htm
http://www.aerotechservicesinc.com/article_dirtsports.shtml

George
 
I'm also very skeptical about sealing the entire tank with a sealer. Extreme care would have to be taken to ensure that you completely clean the tanks first, then dry them completely and then, finally, apply the sealer. Even then it's not guaranteed that they'll remain sealed. If you miss a spot you could find yourself back at square one after a couple of months.

The fuel bladder option is interesting, however there are questions to be raised regarding the weight gain and fuel capacity loss.

In fact, does anyone know off the top of their heads what kind of a fuel capacity loss I can expect if I were to install fuel bladders into my fiberglass wing tanks?? I'm guessing it's gotta be at least in the 5% to 15% range.

I've also been researching various cleaners, degreasers and sealers. Does anyone know anything about the following products? Apparently Hirsch's products are very well known in the aircraft industry. Can anyone confirm this? Has anyone on this forum used thes products before?

http://www.hirschauto.com/prodinfo.asp?number=GTS

http://www.hirschauto.com/prodinfo.asp?number=CD

http://www.caswellplating.com/aids/epoxygas.htm


Thanks again for all the thoughts. Let's keep it going!



Grubac
 
Just a quick question on this thread:

Does anyone know of any in-depth studies that have been on the topic of ethanol/methanol-based fuels and their affect on composite fuel tanks?

Doesn't matter if it's aviation or nautical.

Thanks

Grubac
 
Grubac,

You might want to check some of the power boat forums. I remember reading that ethanol based fuels were responsible for damaging the fiberglass hulls on a number of boats when it first came out a few years back.

(Some boats use the hull as one side of the fiberglass fuel tanks and based on the resin used to construct them, ethanol may deteriorate the composites. From what I remember reading and I could be wrong here, the boats impacted were no longer seaworthy and had to be destroyed.)

^^^^ X10. The snook and reds are on the flats in Miami now, and my motor is destroyed, by the evil E. Non ethanol gas here can only be purchased at a marina and it's more expensive than 100LL. Do not go there. Heres a place to start.

http://forums.floridasportsman.com/forum/main-forums/boating
 
Hey

Thanks for your reply. Sorry to hear about your engine. I'm actually interested in knowing if any really indepth studies have been done. I mean something that has been published and really gets into the nitty gritty about the reactions that occur between the alcohol component and the inner surface of the fibreglass fuel tank.

Grubac
 
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