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Fiberglass gas tanks

steve wyman

Well Known Member
For those of you who have contemplated using a fiberglass tank at some point in the future, please read the following post from the
rans S-7 group- it is scary AND expensive!


To: [email protected]
From: [email protected]
Date: Sun, 7 Feb 2010 00:11:32 +0100
Subject: Re: [RansS7Courier] Airworthiness Inspection


Thanks a lot, Buzz. Great post.

Griff

[email protected] wrote:
>
>
> The Good, The Bad & The Ugly: I returned the 912 to Lockwood in July
> 2009 for no compression on all cylinders. I had purchased the engine
> new from Rans. The engine had less than 2 hours total time at that
> point. All the run time was for leak check, carb balance, warm-up,
> etc. Phone calls and email did not get much response. In late Nov, I
> asked Lockwood to tell me exactly what happened to the engine. The
> intake valves had hit the pistons, push rods bent, cam ruined, gear
> box dog gear ruined. The exhaust valves were fine. I 'Googled'
> stuck intake valves and engine damage. The result comes back on
> boating sites with identical symptoms. I figured out then what had
> happened. I had purchased a fiberglass header tank from Joel
> Milloway and the gasoline was dissolving the resin. I sumped the fuel
> system about the 2nd or 3rd day after filling the header tank and
> running the engine and a 'brown snot' came out. I imediately removed
> the tank and replaced it w/ an aluminum tank but apparently the damage
> was already done to the engine. I called Lockwood and told them what
> had happened to the engine. They gave me $7k core credit or a
> complete zero time re-build w/ 2000 tbo for $8.6 (plus tax). I took
> the re-build option. Lockwood called and sent pics when they
> disassemble the engine saying they did not see how they could have
> missed the problem They had to hammer the intake valves out of the
> heads. The intake valve stems were coated w/ black varnish from the
> resin. I picked the engine up the end of Dec. The damage was done
> to the engine in a matter of hours. The good news is the engine
> failed on the ground. The ugly is I am out over $10k. I have asked
> Joel to notifly all who have his tanks and to re-inburse me for
> damages but I'm not holding my breath for the check. If anyone has a
> fiberglass tank, get rid of it asap.
 
It should be noted in the above post, that the problem with the fiberglass tanks, seems to stem from their apparent incompatability with gasoline, containing ETHANOL, which most of us will be using, at least, to some extent. Steve
 
Fiberglass Tanks

Wrong epoxy for the application, not rocket science, but it does need simple attention to the basics....... :rolleyes:
If someone built a spar from recycled beer cans and it failed, it wouldn't mean that all aluminum spars should be ripped out and proper aluminum never used again. There are many composite tanks in use with the crummy auto gas blends around that are working just fine. Still wish they would keep corn fuel out of at least one pump so we could get full use of the power available in this basic fuel and the STCs would still be intact for certified engines.
 
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Just be thankful we aren't boaters! A good number of boat hulls have been ruined by ethanol in the fuel and now way to repair them.

The worst part is Obama wants to use more and more Ethanol in our gas supply. Check out this news story.
 
This issue has been discussed several times in a Just Aircraft forum since we use fiberglass tanks in them. The final answer to the problems we were having seems to be solved by rinsing the brand new tanks initially. If the tank is made correctly & rinsed properly it seems to work without any breakdown issues. My Highlander flew trouble free after doing this with no indications of tank breakdown.

Here are a few of the several discussions on that board. You can search the forum for sticky valves, ethenol, etc. to see many of them but here are some threads:

http://www.wingsforum.com/viewtopic.php?t=15200&highlight=sticky+valves

http://www.wingsforum.com/viewtopic.php?t=15291&highlight=sticky+valves

http://www.wingsforum.com/viewtopic.php?t=15534&highlight=ethenol
 
All Glasairs are built with Vinelester. Tanks as well, as it is integral to wing.
Never heard of a problem. Then again I suppose most people flew with Avgas which is etanol free.
As a matter of fact, Glasair tech told me many years ago, that vinelester was designed to be chemical and fuel resistant from the start.
 
All Glasairs are built with Vinelester. Tanks as well, as it is integral to wing.
Never heard of a problem. Then again I suppose most people flew with Avgas which is etanol free.
As a matter of fact, Glasair tech told me many years ago, that vinelester was designed to be chemical and fuel resistant from the start.
It's the ethanol that causes the problem- if all you ever use is 100LL, it won't be an issue. That will not be the scenario for most of us running the 912 in the RV-12. Steve
 
It's the ethanol that causes the problem- if all you ever use is 100LL, it won't be an issue. That will not be the scenario for most of us running the 912 in the RV-12. Steve

Kinda makes me wonder what will become of Glasairs the fatefull day 100LL ceases to exist.
 
This is a quote from one of my partners, a Pulsar builder/pilot and an engineer with 20+ years working on aerospace composites:

"You do not want to use a glass tank bare. Depending on the particular resin system used, some may have less resistance to ethanol dissolution and may allow the glass and resin to gradually breakdown. You have to coat the inside wetted surface with a blocker like Jeffco 9700, an epoxy based sealer that is immune to ethanol. I have a glass tank on my Pulsar which has used only mogas with 10% ethanol for over 5 years and absolutely no breakdown of glass because of the Jeffco."
 
I've noticed that when looking at build logs for most glass aircraft with integral tanks, they always coat the inside of the tank with a sealant prior to final assembly.

What about a welded aluminum tank? That would seem to be the best option.
 
Kinda makes me wonder what will become of Glasairs the fatefull day 100LL ceases to exist.
As I understand it, if they do get rid of 100LL, Avgas will become about 94 octane unleaded. If that does occur, it will not have any ethanol, and will be the ideal solution for us Rotax 912 operators. Steve
 
This is a quote from one of my partners, a Pulsar builder/pilot and an engineer with 20+ years working on aerospace composites:

"You do not want to use a glass tank bare. Depending on the particular resin system used, some may have less resistance to ethanol dissolution and may allow the glass and resin to gradually breakdown. You have to coat the inside wetted surface with a blocker like Jeffco 9700, an epoxy based sealer that is immune to ethanol. I have a glass tank on my Pulsar which has used only mogas with 10% ethanol for over 5 years and absolutely no breakdown of glass because of the Jeffco."

Jeffco tank sealer is good stuff. the lancairs use this for tank sealant. It is easy to tell a tank that doesn't have it, eventually it will end up weeping pretty bad.

I would use it for any composite fuel tank, doesn't matter if it is vinylester or epoxy
 
Derakane is the ticket

Derakane vinylester resins, which is what the glasairs (411 type) use is very resistant to gas and the additives. Derakane 470 is used to make the underground fuel storage tanks so it would seem to make a good sealer coating on the inside of an existing tank, or to make an aux tank for the baggage compartment.
 
NO auto fuel in fiberglass tanks

Naturally, how fuel interacts with epoxy depends on the epoxy chemistry, and the fuel chemisty. It was well established in the canard community that auto fuel in the RAF and Hexel Safe-T epoxies, did cause softening of the epoxy resin over time.

However, Aviation fuel does NOT cause any issues with fiberglass/epoxy integrity (using the above epoxys).
 
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