VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 12-19-2008, 03:58 PM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
Default Ethanol and aluminum tanks

Some time ago it was reported that ethanol may be corrosive to aluminum. At the time I looked inside the fuel cap opening and observed that my tanks appear quite new and shiny after using up to 10% of the stuff with mogas for some 4 years with the Subby.

Today I arrived at the point where it was time to check out the fuel system with the Lycoming install but before pouring some 100LL into the tanks, which have been empty for a few months, I had another look at the condition of the skins. Wow, they are not new and shiny looking anymore.

There was a film on the skin surface that could be removed with a rag on a stick. The substance that came off with the stick and rag was black. After fuel was poured in, the tanks looked new and shiny like before. The film, whatever it is, is only visible when the tank skin is dry.

I do not know what the film is. It could be corrosion or something different. In any event, I am off the ethanol kick. From here on it will be mogas without the stuff or 100LL.



__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
Reply With Quote
  #2  
Old 12-19-2008, 05:01 PM
frankh's Avatar
frankh frankh is offline
 
Join Date: Jul 2006
Location: Corvallis Oregon
Posts: 3,547
Default Question

Are you sure the film was caused by ETOH?..Seems a bit drastic if you have been quite happy with 10% mix in the soob.

The material compatibility issues notwithstanding.

Frank
Reply With Quote
  #3  
Old 12-19-2008, 06:57 PM
mannanj's Avatar
mannanj mannanj is offline
 
Join Date: Jan 2005
Location: Mtns of N.E. Georgia
Posts: 1,322
Default Residue

My guess is that it is a form of residual "shellac" that happens with most all very old mogas as found in old lawn mowers etc. The fact that you probably drained all the gas before storing probably prevented a lot of sticky goo in the bottom of the tank and the lines.

Of course as usual I have been wrong before!
__________________
LAUS DEO
Mannan J.Thomason, MSGT. USAF (RET)
VAF788
"Bucket List" checkoff in progress!
Reply With Quote
  #4  
Old 12-19-2008, 09:29 PM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,147
Default

Sounds like you have some of the heavier petroleum distillate carryover from the refinery. Not uncommon, it's basically a light wax that is dissolved in most fuel, and will deposit on the sides of the fuel tank as the fuel evaporates. New fuel will dissolve it again, and it burns just fine. Ethanol exposure (or lack of) is not the cause of this. This the main component of the "shellac" or "gum" associated with old fuel, and is more plentiful in lower octane mogas versus premium mogas.

The clue is the fact that you rubbed off a dark substance on your rag - ethanol tends to oxidize the aluminum surface to a much deeper level than you would otherwise see, which results in a whitish chalky layer on the surface that does not disappear when wetted with fuel. Alodining (or anodizing) all the fuel-wetted aluminum surfaces will protect you from ethanol-induced corrosion effects.

Feel free to stay away from E10 if you like - but this is not the corrosion you would see if E10 were at fault.
__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.

Last edited by airguy : 12-19-2008 at 09:32 PM.
Reply With Quote
  #5  
Old 12-20-2008, 07:32 AM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
Default

Quote:
Originally Posted by airguy View Post
Sounds like you have some of the heavier petroleum distillate carryover from the refinery. Not uncommon, it's basically a light wax that is dissolved in most fuel, and will deposit on the sides of the fuel tank as the fuel evaporates. New fuel will dissolve it again, and it burns just fine. Ethanol exposure (or lack of) is not the cause of this. This the main component of the "shellac" or "gum" associated with old fuel, and is more plentiful in lower octane mogas versus premium mogas.

The clue is the fact that you rubbed off a dark substance on your rag - ethanol tends to oxidize the aluminum surface to a much deeper level than you would otherwise see, which results in a whitish chalky layer on the surface that does not disappear when wetted with fuel. Alodining (or anodizing) all the fuel-wetted aluminum surfaces will protect you from ethanol-induced corrosion effects.

Feel free to stay away from E10 if you like - but this is not the corrosion you would see if E10 were at fault.
Thanks for that observation, it makes sense.

The skin under the film is in very good shape, almost new looking.

It's always good to hear from someone who knows the science behind what is going on.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
Reply With Quote
  #6  
Old 12-23-2008, 11:03 PM
DaveWelch DaveWelch is offline
 
Join Date: Mar 2005
Location: Huntsville, AL
Posts: 427
Default

About using mogas...does anyone use "Stabil"? or other gasoline treatment purported to reduce formation of shellac and bad stuff in aging fuel? Results?

Also, I noticed recently an Stabil advertisement proclaiming an new product formulated specially for mogas with ethanol in marine applications. Wonder if that would be worth considering in our aircraft? What say you guys? Any thoughts, knowledge or experience in this realm?

Dave.
Reply With Quote
  #7  
Old 12-24-2008, 01:06 AM
jarhead jarhead is offline
 
Join Date: Jan 2006
Location: PA
Posts: 264
Default

Quote:
Originally Posted by DaveWelch View Post
About using mogas...does anyone use "Stabil"? or other gasoline treatment purported to reduce formation of shellac and bad stuff in aging fuel? Results?
I use Sta-Bil in my outdoor stuff (mower, pressure washer, generator, snowblower). Everything starts easily after the off-season.

No experience with mogas/Sta-Bil in an aviation capacity...
__________________
Ken

Helicopter mechanic (A&P)
USAFR KC-10 Boom Operator, on final approach to retirement
My RV-9/8/7 dream may be on life support, but it ain't dead yet!
Reply With Quote
  #8  
Old 12-24-2008, 01:12 PM
chaskuss chaskuss is offline
 
Join Date: Mar 2005
Location: SE Florida
Posts: 1,499
Default StaBil

Quote:
Originally Posted by DaveWelch View Post
About using mogas...does anyone use "Stabil"? or other gasoline treatment purported to reduce formation of shellac and bad stuff in aging fuel? Results?

Also, I noticed recently an Stabil advertisement proclaiming an new product formulated specially for mogas with ethanol in marine applications. Wonder if that would be worth considering in our aircraft? What say you guys? Any thoughts, knowledge or experience in this realm?

Dave.
Dave,
I have not used it in aircraft. However, I use it in any gasoline powered device which does not operate regularly. I once placed it into my 900cc Ducati, which did not run for four years. After changing the oil and installing a new battery, the bike started right up on that 4 year old gasoline. StaBil is great stuff.
Charlie Kuss
Reply With Quote
  #9  
Old 12-24-2008, 04:23 PM
DaveWelch DaveWelch is offline
 
Join Date: Mar 2005
Location: Huntsville, AL
Posts: 427
Default

Yup, I put Stabil in every one of my gas cans before I go to fill 'em. I use it in every mower, string trimer, pressure washer, leaf blower, chain saw, mulcher and vehicle I'm not going to drive for a while. (Between engines taht are running and those that I'm "going to "ix someday", the ol' cylinder index is getting way up there!) Never had a problem starting again after the "off season". Hard to imagine that it wouldn't be beneficial to our Rotax's, but I'm going to ask 'em if no one else has already!
I'll let you know what they say,
Dave.
Reply With Quote
  #10  
Old 12-27-2008, 07:47 AM
avee8tor13 avee8tor13 is offline
 
Join Date: Dec 2008
Location: Northern VA
Posts: 141
Default Ethanol in tanks

All,

I talked to those folks using pure ethanol in their rv-3, 4 and 8 with lycoming engines and they told me othe only thing they did was change the injectors and I think they made a small mod to the distribution manifold. Evidently these folks have been using ethanol sine early 90's. Ck out this link.

http://www.ethanolairshows.com/
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 08:17 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.