REFLECTOR: Auto fuel
Ron N Velocity XLFG
VelocityXL at fastmail.fm
Mon Mar 19 12:22:27 CDT 2012
My experience is that the jefo holds up but if there is any pin hole through the Jefco then the solvent will get behind the jefco and break up the epoxy and melt the foam. Again the jefco was fine the Epoxy on the back is what broke down for me.
Ron
----- Original Message -----
From: John Dibble
To: Velocity Aircraft Owners and Builders list
Sent: Monday, March 19, 2012 10:06 AM
Subject: Re: REFLECTOR: Auto fuel
While xylene is a strong solvent, the data sheet shows xylene to have no effect on Jeffco and that leaves me in question about the cause. Do I understand correctly that no damage was found on the tank sides? If so, how is that explained? With the top damage concentrated at the filler neck, that is consistent with my water concentration theory. Water condensation has been observed in this area and the metal gas cap provides the best heat transfer and therefore greatest condensation. Once water condenses, the oxygen containing additives will migrate to it, more slowly than if the water is at the bottom because the additives must diffuse through the vapor space. However the eventual equilibrium concentration will be the same. FWIW
John
3/18/2012 10:05 PM, Andy Millin wrote:
Bill's situation does not appear to be a pinhole. It is systemic on both the tops and bottoms of both strakes. The problem manifested itself on the top of the strakes (both simultaneously) at the filler neck. The strakes are technically still sealed. However they are soft and the structure is compromised. His plane is grounded until major repairs are completed. Bill researched the fuel, it's additives, and the dates they were introduced. This along with the type of damage led him to the xylene.
The specific culprit is academic at this point. The damage is done. The formula of the fuel made for cars is not published and subject to change. Bill did not find out about it until after the damage was done. Unless he can find a secure, bonafide source of pure gasoline, he will be using avgas.
Andy
==========================
Andy Millin
amillin at sbcglobal.net
On Mar 18, 2012, at 9:26 PM, Mark Magee <edjonesbrady at gmail.com> wrote:
Back in the late 80's and early 90's most of the Long EZ community running the 0-235 were running Mogas. Never heard of a problem and this was before Jeffco was recommended. Our concern was always a pinhole in the tank seeping into the foam. I know the Mogas formulation has dramatically changed since then, ethanol etc. Nonetheless, a pinhole leak remains a problem as it would be in any gas tank! You just have to think that the potential for a pinhole leak will increase with any fuel tank, made of -any- material as it ages. The sloshing compounds have minimized this but can't prevent it. If the pin-hole seeped 100LL does less damage than Mogas, Hurray? I suppose.
Pinhole leaks just don't upset the aluminum birds as much as they don't degrade the superstructure once out of the tank. But they still get them and are expensive to repair. Initial sealing of tanks is important, yet will not guarantee a flexing composite structure won't develop a pinhole.
Chemistry of fuel can't fix a pinhole :(
Mark Magee
N34XL XLFG 300HP 80 HRS
Brady TX
On Sun, Mar 18, 2012 at 7:57 PM, Dennis Martin <dennis.doc at gmail.com> wrote:
Kurt,
Sorry to hear your Jeffco "protected" Cherokee tip tanks are afflicted. This only adds to the mystery, and supports the notion that we're gambling by filling our V tanks with mogas. Maybe not high risk, but enough risk to raise the ante higher than I want to pay. Let's hope some petroleum engineer out there can help figure this out. Perhaps we could contact Jeffco. My guess is that they will swear that Jeffco is impermeable to all distillates. I'm just happy that I bonded my tanks with a layer of veil before applying Jeffco, and then applied an extra coat or two of the gray stuff.
Dennis
On Sat, Mar 17, 2012 at 10:45 PM, Dennis Martin <dennis.doc at gmail.com> wrote:
Kurt,
Stories suggest that mogas takes significant time to do its damage, and your experience supports that theory. However, maybe the additive mix in New Mexico is a lucky brew we won't find in other regions. I've never put mogas in my tanks, but I was thinking about using mogas for extended X country trips that require say two or three tanks of fuel. If most of the mogas is consumed on the trip, and then you top off with 100LL upon returning home, your tank might end up with 20% mogas for a few days. Is it worth the risk to save $50 or $100? Perhaps the risk would be minimal or non-existent. Opinions?
Dennis
On Fri, Mar 16, 2012 at 10:55 AM, <nmflyer1 at aol.com> wrote:
Thanks!
That is definitely some good information to know. I inspected my tanks this week. I have had Clean Mogas in there for about a year (being cycled through as I run things). So far, no problems. I used a scope to look around as well as checked for leaks and soft spots in the tanks/sump.
Not knowing what blend of fuel you may get is the scary part. As was mentioned, there are many different blends based on company requests, location, time of year, etc. I suppose the only safe way to use Mogas in the V would be to find the exact name of the additive that is causing the problem.
I am part owner in the 100LL fuel company at my Airpark. When we take delivery of our fuel load, we get a spec sheet that gives all the details of that fuel load. I would assume that that is a rule.
One thing for sure, It is not worth the problems in the V to save a few bucks.
Thanks again,
Kurt
-----Original Message-----
From: Mike Dawson <medawson250 at yahoo.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Fri, Mar 16, 2012 10:37 am
Subject: REFLECTOR: Auto fuel
To all who use Auto fuel,
Here is Bill Mulrooney's response to my brother's inquiry of his auto fuel / mogas experience.
For those who do not know, Bill and his partner built a Velocity with a 427 V8...N427VA....it boogies!
Hi Bill,
"Sorry to hear your having issues also. I live in West Bloomfield Michigan. I'd be happy to talk to you about your problems and what I've learned from my problems. Alcohol isn't the problem, it's the fuel injector cleaners that they started adding 9 months ago. It is such a small molecule it literally slips threw the Jeffco coating in the tanks. Our tanks look perfect inside but the fittings in the sump tank and the foam in the stakes just took a shit on us! I'm still pretty sick about it! I'm going to make the sump tank out of aluminum and were removing the outer glass skins and foam and adding another coat of Jeffco to the outside of the inner skin followed by 8 to 10 layers of bid. Then foam and then the outer layer of glass again. The wheel wells are about 1/8 " of glass and they look perfect still. Our plane has had auto fuel in it since 2004 with no problem till August 2012. The vapor build up between the inner and outer glass and then popped the glass loose around the fuel fillers on both sides. That was just after Oshkosh 2011. Then the foam started to sink in on the glass. Then we stopped flying it. "
Bill Mulrooney
I stopped by my non branded Commercial Fuel Network outlet yesterday and this is what I learned. While there is no Ethanol in their fuel they service several stations. IE Chevron, 76, Mobil, Shell etc. Fuel received from the refinery contains the additives for that company's fuel. Consequently the fuel they sell to me , as non branded with no Ethanol, contains different additives or blends of additives from each company. They guarantee no Ethanol but any combination of additives after that are anyone's guess. So Kurt et al take heed. I'll be using 100LL for now!
Mike Dawson
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--
All the best,
Dennis
--
All the best,
Dennis
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