Mogas in epoxy tanks

[Dust]

Well, cozy builders are just happy to be flyin

Longs are happy to be spiffin up their planes for better everything

Vari drivers have been there, done that and knows it!

Was talkin to my Vari buddy last night and he asked me if i was planning on using mogas, i said, 100ll for me.

He then proceeded to tell me of the vari flier that was in the same hangar as him a number of years ago. The guys needle and seat in his carb kept giving him trouble, sticky goob was being deposited on it and he kept having to clean it.

Finally the engine stopped or was it that it would not start - no matter - he had to figure it out. The Mogas had desolved some part of the epoxy and it had clogged the fuel filter so that no fuel would flow.

The epoxy had also been trashed all the way to the outside skin and he said burt had a word for this, i believe it was, he had spongy tanks. the tanks had to be completely removed and replaced.

SOOOOOOOO, If I were you and i was gonna use MOGAS I would check this out and figure out what coating you have to use that is impervious to car gas.

It has something to do with either the regional or seasonal additives that are put into auto gas

[ZG4Me]

Originally Posted by Dust

SOOOOOOOO, If I were you and i was gonna use MOGAS I would check this out and figure out what coating you have to use that is impervious to car gas.

It has something to do with either the regional or seasonal additives that are put into auto gas

'S called alcohol, slowly softens epoxy.

Vinyl-ester resin seems to be pretty immune. High Tg, stinks like polyester resin, smoking fast cure times, not quite translucent (milky) when cured.

I read a KR pilot used it in his tanks, had test coupons sitting in a jars of ETOH and gasahol for years, no softening. So he says.

Suitable as a coating in a predominately epoxy canard? I dunnow, but it is called experimental aviation...

Rick

[Dust]

well, common sense on the internet says that epoxy and mogas is fine. it appears not so.

As to wether your solution will work??? might de-solve the foam under the epoxy, that, i believe, is why we do not use the stuff to begin with.

It might be alcohol and it also might be some of the other of a multitude of additives, i dunno, i'm not concerned for myself as i will not be using mogas

[Dust]

Originally Posted by mplafleur

I think it's fairly common knowledge that auto fuel MAY have a detrimental effect on our tank interiors. Everybody's been told several times to fill a jar with fuel and stick a coupon of your epoxy inside and seal it up. Look at it many years later when you are finishing up your bird.

The problem now is that fuel additives are changing. More alcohol.

Time to fill another jar.

I strongly disagree, i have read everything posted here and a big deal was NOT made of the fact that auto fuel disolves epoxy tanks and has been common knowledge for 15 or 20 years.

I have also asked a few members that have built thier strakes and are/were planning on auto gas if they had notice the few items that were posted over the years about the subject and they had not.

I remember few posts where someone had a concern and everyone just brushed them off.

A BIG DEAL should have been made when anyone mentioned the use of an auto engine or auto fuel. it clearly was not.

My point - do not rely on the internet, the info needed to modify the plane in any way is just not here or there, get to know a few vari and long fliers and talk to them directly, not over the internet.

[mplafleur]

I will include a qualifier.

Anyone who reads the canard or rotary e-mail lists should be aware of the possible effect that increased alcohol content in road gasoline may have on the epoxy in their fuel tanks. It been a topic of discussion more than several times.

[neverquit]

Keith Spruer - 2005...I've been burning only mogas for 6 years and 540 hours, except when I
travel and have no other option but to buy the dreaded leaded. No
problems - I have safetypoxy/expoxy tanks.
Al Wick, 2005...Since I planned on using auto gas from day 1, I put pieces of epoxy and
)))>other fuel tank components in Mason jar. I then regularly replaced the
)))>fuel in the jar with auto fuel. None of fuel tank components were
)))>affected. 6 years later my plane was complete and the mason jar
)))>components good as new. So I have operated for years using auto fuel
)))>which often has ethanol and other undesirables. Others have done same
)))>tests, same results.
Nat Puffer, 1999...Builders,
Because of recent postings on auto fuel, I called the EAA to inquire about
the extent of their STCs on auto gas. They obtained approvals for the
Lycomings through 150hp, but not the 160 hp 0-320 or the 180 hp 0-360. They
referred me to Peterson Aviation, in Nebraska. I called Peterson, and they
said yes, they have the STCs on the 160 hp and 180 hp Lycomings. They said
for factory builts, you have to purchase the rights for both the airframe
and the engine. For homebuilts, not to worry. He said that they did not get
any detonation on 91 octane rated auto fuel in the 180 hp Lycoming
(detonation is a function of compression rating). When I asked about
oxygenating additives (we have those in Arizona because of air quality), he
said the additives MTBE and ETB are approved, but not ethyl alcohol
(ethanol). He said the objection to ethanol was a materials compatibility
problem with diaphragms, hoses, etc. He also suggested that vapor pressure
could be a problem, which is the reason you need approval for the airframe
as well, because the airframe (high vs low wing) determines the routing of
the fuel lines and the susceptibility to vapor lock. I don't know how
accurate this is, but he suggested you might lose the higher vapor pressure
alcohol at altitude, which would reduce the octane rating and might cause
detonation at lower altitude (I don't know if this has been proven). If we
lose 100LL some day, we may have to switch to mogas whether we like it or
not. So it is reassuring that some have used it for a long time with no
problems.
Best regards,
Nat

There's more in the archives about putting on incompatable tank coatings that delaminate from the epoxy that clogs filters.

[Dust]

So if you go searching you may find the info, but how good is the info.

If you just find a report of no problem, then you stop!

As any who read me often they know i am a chicken and wish to have bullet proof systems.

Hearing of one planes tank that dissolved from the use of MOgas is scary stuff and in my opinion every time a newby says they are going to use mogas in a fiberglass tank, they should be made aware of the potential problem.

Every time

[Dust]

Well, if i were to consider using mogas i would only do it with a long term test of the epoxy that i am using in a variety of mogas fuels.

I would also add to the samples regularly in case new additives had been added.

The damage that these fuels do to a tank is not repairable, whole new tanks must be fabricated and we all know how much fun that is!

Reading the experience of some does not mean that the epoxy you are using will work with all available fuels - having read them it would give me that impression and i feel that impression is wrong