Mogas use and E-10 warning

I recently had an email discussion with my friend Kent Misegades regarding the use of mogas and E-10 in my Lycoming engine. Kent is a director of the
Aviation Fuel Club, an aerospace engineer, and aviation journalist for EAA and GA.

Kent put me in touch with Todd Peterson who has done extensive research on the use of mogas in aircraft and has issued over 34,000 STC's for autogas use. I thought the forum members could learn something from Todd's letter:

Ron & Kent:

No one has said that our engines won't run on E10, they'll run on it just fine. However there are problems with corrosion, increased possibility of vapor lock, phase separation, etc.

Go this link:
http://www.google.com/url?sa=t&rct=...sg=AFQjCNGnGeP2w-SxLxnohUFAdyCzMHlHgg&cad=rja

If the link fails, go to Google, Advanced Search, then type in the phrase University of Aachen, and have EASA and Ethanol in the other fields and it'll give you a link to this report which was requested by EASA.

What I've found from the people I've spoken with, is that you might get away with using E10 if you keep the fuel fresh, and by that I mean never leave it in the airplane for more than a week without replenishing it, This seems to put a stop to materials compatibility issues. It does not eliminate the potential for corrosion of the fuel system and and engine nor does it do anything to eliminate the water absorption problem. Leaving it in for longer than that can ruin carburetors too. I've had a couple reports of that happening.

If your were to build an RV from the ground up with ethanol compatible components, then the only place you might see corrosion is of course still the engine, and then whatever metal is used in the fuel system. Doing that however would fix it as far as seals and gaskets are concerned. However if you read that EASA report you will see that the U of Aachen states that, depending on the alloys used in the engine, using E10 just once, will start corrosion within the engine and it never stops even if you never burn another drop of ethanol.

If you're flying in a humid environment it is possible for the ethanol in the tanks to draw sufficient moisture into the fuel to give a poor running engine by the end of the flight. There's no way I can think of to fix that problem that the FAA would accept.

You probably already know that range will be about 15% less on E10, which isn't a problem as long as you know it ahead of time.

I don't know what is in Lycomings fuel pumps but whatever it is is compatible with E0, but I wouldn't think it would take E10.

People tend to think it wouldn't be a big deal to see E10 approved but from my experience, I could spend 20 years and 20 million dollars and still not see it approved. Of course in an RV that doesn't matter but if I had one I'd never burn gas with ethanol in it.

I have to recommend against using gasoline with any amount of ethanol, whether the airplane is certificated or not and regardless of how often you fly, and hence regardless of how old the fuel is. It's a bad mixer. Feel free to let other RV owners read this if you wish.

Todd L. Petersen
Petersen Aviation, Inc.
984 K Road
Minden, NE 68959
308-832-2200

And of course then, there is your car, lawnmower etc to think about. Not the same safety issue but certainly not good. Unfortunately, burning lead is more harmful to your brain so I don't think the problem will improve with time. In fact, you can no longer get non-ethanol fuel in and around most large communities. That said, it would be nice to see a better effort made towards innovating more compatible engine materials. Brazil already puts tremendous amounts of ethanol in their fuel from sugar cane and everything flies with it. If you believe Todd, which I do, planes should start falling out of the sky soon in that country. By the way, one of the best places to find Mogas without ethanol is in the corn growing states where it is produced. Ironic, but ethanol mandates are driven by bad air quality.

I'm not a fan of E10 but I've burned a lot of it in my RV and never saw any signs of corrosion, anywhere, and still don't see any signs of corrosion in the tanks. That said Mark Frederick used to run E85 in his Rocket and never had issues.

Peterk said:

And of course then, there is your car, lawnmower etc to think about. Not the same safety issue but certainly not good. Unfortunately, burning lead is more harmful to your brain so I don't think the problem will improve with time. In fact, you can no longer get non-ethanol fuel in and around most large communities. That said, it would be nice to see a better effort made towards innovating more compatible engine materials. Brazil already puts tremendous amounts of ethanol in their fuel from sugar cane and everything flies with it. If you believe Todd, which I do, planes should start falling out of the sky soon in that country. By the way, one of the best places to find Mogas without ethanol is in the corn growing states where it is produced. Ironic, but ethanol mandates are driven by bad air quality.

Click to expand...

There has been a mind set against ethanol in airplanes since day one, especially within the STC process. EAA did a lot of testing of mogas to get the STC's approved and so has Petersen Aviation. But how much of it was burning E10? For sure some of the statements about ethanol are based on wives' tales and not science.

If ethanol is so corrosive to engine metal parts, how come automobiles run forever on it, in fact longer than they did before it was introduced? My Honda Pilot is at 150,000 miles all of it burning E10. The engine does not leak oil, runs as smooth as ever, plugs last over 100,000 miles, and mpg are the same as always. The only maintenance this engine has had is a regular oil change, air filter changes and the recommended timing belt change. Plugs were changed at 100,000 but still looked very serviceable.

My gut feeling is the bias against E10 is based as much on politics as science. I don't like the stuff and wish it would go away but do not believe everything negative said about it.

Ethanol in gas was not the wisest decision we have made. However, you don't have to use it - it's not against the law to buy Ethanol Free Gas, it's only an EPA Mandate. The only law is that a sticker must be on the pump if the gas contains ethanol.

Try finding Ethanol Free Gas in your area:

http://pure-gas.org/
http://www.buyrealgas.com/

John

Good luck with that in California.

http://www.vansairforce.com/community/showthread.php?t=58334&highlight=vanguard+ethanol+stan

Why doesn't anybody believe the Vanguard pilots?

We've read all these concerns elsewhere ad infinitum, just different emphasis on various lethalities. I avoid the stuff, fortunate to have one clear-thinking outfit nearby that charges more than neighboring competition, but that's because they truck non-ethanol fuel from Salt Lake refineries. (They are the Ultra-Touch car wash stores and a handful of others in the Boise area.)

Ethanol is political, not air quality driven, as mistakenly stated above. Back in the '90s it was introduced in lieu of MTBE, but now it's a green mandate chock full of renewable nonsense that in spite of mandates, tariffs, and subsidies is rejected by the market.

John Siebold

One thing in the research that stuck for me was the strong recommendation to not let E10 "sit". Most cars do not sit. I have the odd situation of extremely low mileage vehicles (eg my truck has gone just 600 miles in 2 months and the car has traveled less) and can tell you that the vehicles are not happy about it. My mechanic finds little things each year.

Yes, my airplane has gone considerable further than my two vehicles combined.

I can imagine the steel fittings on the RV-8 fuel system would not be happy with E10 sitting idle.

I hope (and expect) to see E0 of some form approved for aviation. I also hope to see it at more airports. But time will tell.

Isnt ethanol the stuff we drink in our booze???

Methanol on the other hand is way bad and corrosive stuff, as I recall.

Any chemists out there???

In Kansas I know they do not have to put a placard on the gas pump unless there is more than 10% alcohol. I have found one station in my local area where the 91 octane pump does not have alcohol, I verify it everytime I use it. Due to winter grade of fuel I do not use auto gas during the winter months due to past vapor lock issues on a warm day in January.

Ethanol

My comments on ruined carburetors, water being pulled into the fuel, and on how long E10 can sit in your tanks, comes from reports I've received from a number of pilots in the US, which seem to corroborate each other, not from any testing I have done. My comments on corrosion come from a study commissioned by EASA and completed by a major university in Germany in the last two years, and on what was found in studies commissioned by Cessna in the 1990's.

In respect to engine corrosion, note that the EASA study says "depending on the alloys" used in the engine.. In other words it's not going to cause corrosion in ALL engines but will in some. If it's a high time engine then maybe that doesn't make all that much difference. If you have an unlimited budget, then corrosion might not be an issue either.

Water being pulled into the fuel in the tanks, via the tank vents is not a problem in modern cars because they have a closed vent system. Our airplanes do not. It should also be kept in mind that our aircraft engines are air cooled, not water cooled, that they run at full power for takeoff, and then somewhere above 65% during cruise. No one runs their cars that way, and before someone points out that Nascar is using ethanol, all that proves is that if you have the funds, it's not painful to replace components.

The Vanguard Squadron uses 100% ethanol. Again, no one says that the engines won't run on it. 100% ethanol has an octane rating that I think is somewhere above 130. So there's no question about it operating without detonation in even the largest of engines. Is anyone using it in their warbird? Given the octane rating, I should think it'd be the obvious choice to replace 100LL in the B-29 or a P-51 or in any of the largest of engines that are being threatened in respect to the high cost and availability of Avgas. How many warbirds are flying on it right now?

Perhaps the answer is zero because it's been tried and as far as I can tell, it's failed. Look at the ethanol program at Baylor. It ran from the early 1970's to the early 1990's and how many STC's did they accumulate? I think about three but correct me on that if I'm wrong. However many it was, I'd be interested in knowing how many of those STC's are being used in the field right now. Given the prevalence of ethanol today I'd think that if anyone were using those STC's that someone would have made a big splash in the aviation press about it long before this.

It has also been tried by South Dakota State University. They were actively testing AGE-85, the "aviation" equivalent to E-85 in the early 1990's and perhaps they still are. How many STC's have they accumulated? I'm aware of two but there may be more and again, are those STC's being used anywhere in the field? I don't know, maybe so. If anyone is using one of those STC's that is reading this, please speak up.

Cessna was concerned when South Dakota State was testing 85% ethanol in their airplanes so they commissioned a study. It found that corrosion was so serious with AGE-85 that fuel pumps were breaking down in as little as a couple of hundred hours. It's been years since I read it but I think there were airframe corrosion issues as well, insofar as if the fuel system leaked, then wherever the fuel ran you'd also get corrosion. That's probably enough to stop more than a few warbird owners from pursuing its use in airplanes that are irreplaceable, but if the airplane is modern, requires no STC to to modify it, and has the backing of an ethanol company such as POET, then certainly the Vanguard Squadron can fly on ethanol at air shows. I would call that, and what Nascar is doing, part of the larger disinformation campaign that ethanol proponents have been waging for forty years. I maintain that if it worked, if it actually worked, someone would be selling STC's for it and right about now they'd be selling like hot cakes.

When we doing our testing we thought about testing with ethanol blends as well and the FAA was fine with that. However as we started to get into it we quickly became aware that testing for ethanol was going to quadruple the cost and time necessary to accomplish what we were trying to do. Imagine if you will the amount of time it would take to do the research, conduct tests, and create drawings for the FAA for the replacement of fuel system elastomers in our fleet of 40 to 60 year old airplanes, all of which had revisions to their fuel systems as they changed models through the years which would only serve to complicate matters. Once that were done, one would still have to evaluate it for corrosion, wear, vapor lock, water and phase separation, detonation etc, At the time we were testing, ethanol was nothing more than a novelty, and Baylor had been testing for ten years before we entered into it, hence the decision was made to stick with testing conventional gasoline only, and that's what we did.

I would very much like to be selling E10 STC's today, but not if I had to constantly worry about people actually using them. Any pilot who wants to burn ethanol, especially in non-certificated airplanes, certainly isn't being prevented from doing so, but from what I can tell, it'd be a mistake.

Todd L. Petersen
Petersen Aviation, Inc.

johngoodman said:

Ethanol in gas was not the wisest decision we have made. However, you don't have to use it - it's not against the law to buy Ethanol Free Gas, it's only an EPA Mandate. The only law is that a sticker must be on the pump if the gas contains ethanol.

Try finding Ethanol Free Gas in your area:

http://pure-gas.org/
http://www.buyrealgas.com/

John

Click to expand...

We have Ethanol Free 91 Octane Gas at our local station. They have a sticker on the pump (Ethanol Free). Got some today.
Squeak

Welcome to VAF!!!!

Todd, welcome aboard the good ship VAF.

Great to have you here, thanks for all the work you have done over the years on the mogas issue.

Things I know:
- Alcohol is more corrosive to aluminum than gasoline or water.
- Alcohol absorbs water.
- Alcohol has lower energy content than gasoline, all other thing being equal, you will burn more fuel if you use alcohol.
- Alcohol can destroy some polymers (gaskets and seals), but there are materials avialble that avoid this problem.
- Alcohol is less susceptible to pre-ignition or detonation than gasoline (it has a higher octane rating) an can be run at higher compression ratios and/or higher temperatures.

Things I don't know:
- Is the rate of corrosion a concern in a Lycoming? I don't know. Probably not.
- Is the water absorption a problem in an airplane?

I think these are the basic issues.

HTH

Tim

Hey Todd. Aren't you the guy who sells the expensive Adel clamps that go on push rod shrouds and don't hold anything?

Todd L. Petersen said:

My comments on ruined carburetors, water being pulled into the fuel, and on how long E10 can sit in your tanks, comes from reports I've received from a number of pilots in the US....

Todd L. Petersen
Petersen Aviation, Inc.

Click to expand...

Thanks for contributing to this discussion, Mr. Petersen. You have been a credible advocate of using mogas for years and your concerns about ethanol are well taken.

My take on the subject is based on using E10 with a Subaru engine on the RV-7A for about 4 years. It worked. (You may recall, I contacted you about the failure of the Hogdes test tube, probably due to the ethanol, and I appreciate your replacing it free of charge.)

But I won't use E10 in a Lycoming engine because no one will say the fuel pump has baffles and seals compatible with ethanol. These materials are available but no company will say whether or not they are being used. The Air Flow Performance fuel injection system is impervious to ethanol, why not a simple fuel pump? Reason, certification rules.

Corrosion is an issue. I have read that ethanol is blended at distribution centers, not at refineries because of pipe line corrosion concerns. But there is some evidence we could live with it in an airplane if the fuel system were designed to deal with ethanol. My experience with the stuff in an aluminum tank over a 4 year period revealed no corrosion evidence at all, and I believe there are others here who will say the same thing.

Corrosion within the engine is a concern if burning E100. That has been told to me by an engine guru I trust. But is there a corrosion issue burning E10? I don't know but if there were an engine driven fuel pump designed to handle E10, I would burn it.

Vaporization is a concern when using mogas but that can be dealt with by using the vapor test device you sell. I used it most every day with the Subaru. The only time I had a low test was with winter fuel late in spring and it had nothing to do with ethanol. I once bought a gallon of E85 and tested it with the Hodges system, it came in about about 62, the same as 100LL.

Again, thanks for the history behind on your concerns about ethanol.

PS The Subaru engine was torn down by a Subby friend, Rod Schnieder in Atlanta, after a serious over-heat. I had lost confidence in the engine and gave it to him for that purpose. Rod reported the engine was like new on the inside. There was no detectable damage from the over heat or anything else (like ethanol). That engine had been run hard at 65% or more on the airplane.

I think this all points to lack of evidence..I.e there just arn't that many airplanes running on E10.

So we are really left with a mixture of reports and personal experience.

As for my personal experience I have about 400 hours an almost exclusively E-10. My airplane resides in a hanger and the premium gas sometime sits in the tanks for a month or two when I'm busy and don't get to fly much..Note I always do at least a half hour round the patch once a week.

Every year I dismantle the steel fuel hose fiting at the FI servo and drain the tanks.

My system is designed to pump Ethanol (i.e no mechanical fuel pump, AFP FI system and o rings changed for flourosilicone in the tank drains).

My personal experience is:

1) No corrosion anywhere, in the tanks or steel fuel fittings. No products of corrosion noticable in filter screens.
2) No seals failed and certainly no vapour lock (it was designed this way after all)
3) No noticable water absorbtion..Not sure how I would know anyway..With FI the surface tension changes you might see with E10 in a carb (if any) are irrelavent.
4) No bad gas as far as is noticable.
5) recent boroscope check revealed a clean top end with no signs of damage (I would hope not!)
6) Running LOP at 24*24 the gas consumption rises to about 7.6GPH vs 7.0 for stright gas or 100LL.


Bottom line..from my experience so far I have no intention of ever running 100LL if I can avoid it. I would avoid E10 but only for the reason its a rip off!

Frank

Mogas vs. E10 vs. Avgas

Mogas with NO "E10" is available in our area, NW Oregon.

Lebanon State Airport, S30, aircraft fuel ramp, next to the Avgas.

Also available at several auto fueling stations in the Salem area.

Usually $1.00 less than Avgas.

Filtered and I never found water on a sump on a fill up from S30.

Savings is around $35 per fill up. Savings of mogas vs. avgas, will pay for all maintenance and some mods.

Standard compression lycoming allows efficient operation on mogas and NO power loss as with E10 fuel.

NickAir said:

Mogas with NO "E10" is available in our area, NW Oregon.

Lebanon State Airport, S30, aircraft fuel ramp, next to the Avgas.

Also available at several auto fueling stations in the Salem area.

Usually $1.00 less than Avgas.

Filtered and I never found water on a sump on a fill up from S30.

Savings is around $35 per fill up. Savings of mogas vs. avgas, will pay for all maintenance and some mods.

Standard compression lycoming allows efficient operation on mogas and NO power loss as with E10 fuel.

Click to expand...

Yes.. I see about a 7% increase in fuel burn on E10. Ad 7% to the average cost of E10 around here (corvallis) and I get an effective price of $3:59/ gallon.

How does that compare to alcohol free mogas?

David-aviator said:

....

If ethanol is so corrosive to engine metal parts, how come automobiles run forever on it, in fact longer than they did before it was introduced? My Honda Pilot is at 150,000 miles all of it burning E10. The engine does not leak oil, runs as smooth as ever, plugs last over 100,000 miles, and mpg are the same as always. The only maintenance this engine has had is a regular oil change, air filter changes and the recommended timing belt change. Plugs were changed at 100,000 but still looked very serviceable.
.....

Click to expand...

The better test would be to run an old air-cooled VW bug for 100,000+ miles on E10...

az_gila said:

The better test would be to run an old air-cooled VW bug for 100,000+ miles on E10...

Click to expand...

I got a better idea..Wait for another 500 hours or so and then you all buy my engine and tear it down and see what mess I've made of the insides after 1000 hours of exclusive E10 use.

Shall we say $30,000 minus accessories of course.

Of course you then sell it back to me for $500, because clearly it will be nothing than a boat anchour at that point...

Frank

compare to alcohol free mogas?

frankh said:

Yes.. I see about a 7% increase in fuel burn on E10. Ad 7% to the average cost of E10 around here (corvallis) and I get an effective price of $3:59/ gallon.

How does that compare to alcohol free mogas?

Click to expand...

Well, you have a cost advantage at the price you quoted of $3.59/gal., but not by much if the 7% loss is factored.

About $4.00/gal. for Mogas.
4.00
- 3.59
= .39 difference before the 7% loss.

7% loss on Mogas = .28 so .39-.28=.11

Your cost saving, going with E10 vs. Mogas, is approximately an adjusted 11 cents per gal.

Disclaimer: Not sure the price today of mogas at S30? May have gone up which would make your saving more on E10.

This assumes you can operate efficiently with standard compression for 91 octane. 8.5-1 compression is efficient with this octane by my test. High compression may require higher octane?

Ok, Gotta get back to work.

NickAir said:

Well, you have a cost advantage at the price you quoted of $3.59/gal., but not by much if the 7% loss is factored.

About $4.00/gal. for Mogas.
4.00
- 3.59
= .39 difference before the 7% loss.

7% loss on Mogas = .28 so .39-.28=.11

Your cost saving, going with E10 vs. Mogas, is approximately an adjusted 11 cents per gal.

Disclaimer: Not sure the price today of mogas at S30? May have gone up which would make your saving more on E10.

This assumes you can operate efficiently with standard compression for 91 octane. 8.5-1 compression is efficient with this octane by my test. High compression may require higher octane?

Ok, Gotta get back to work.

Click to expand...

The 3:59 was the cost adjust price per gallon..i.e it already had the 7% added..so the effective MPG would be the same as straigh gas.

Cost saving is thus $0.39/gallon.


Just for kicks lets assume
a 1:40 effective difference between E10 and 100LL.. over 2000 hours thats $19,600 at 7GPH..thats an engine rebuild at todays prices..

Assuming of course it makes 2000 hours and right now I don't see any reason why it won't

I see no reason to expend lots of effort to adapt aircraft to ethanol. The ethanol mandate is even more idiotic and ill-conceived than MTBE. At some point, the US legislative process should realize this and rescind the use of ethanol.

Excellent comparison display

frankh said:

The 3:59 was the cost adjust price per gallon..i.e it already had the 7% added..so the effective MPG would be the same as straigh gas.

Cost saving is thus $0.39/gallon.


Just for kicks lets assume
a 1:40 effective difference between E10 and 100LL.. over 2000 hours thats $19,600 at 7GPH..thats an engine rebuild at todays prices..

Assuming of course it makes 2000 hours and right now I don't see any reason why it won't

Click to expand...

____________________________________________________________


Excellent comparison display.

You make the great point that fuel savings DOES add up if operated with E10 or straight Mogas.

Ron Lee said:

I see no reason to expend lots of effort to adapt aircraft to ethanol. The ethanol mandate is even more idiotic and ill-conceived than MTBE. At some point, the US legislative process should realize this and rescind the use of ethanol.

Click to expand...

That assumes whoever is driving ethanol is not lining the lawmaker's pockets.

I mean, they have only just realised its probably a good idea not to have congress be exempt from insider trading laws..yet I hear only yesterday that bill is being watered down so they can STILL get away with it.

Follow the money!

RV7ator said:

We've read all these concerns elsewhere ad infinitum, just different emphasis on various lethalities. I avoid the stuff, fortunate to have one clear-thinking outfit nearby that charges more than neighboring competition, but that's because they truck non-ethanol fuel from Salt Lake refineries. (They are the Ultra-Touch car wash stores and a handful of others in the Boise area.)

Ethanol is political, not air quality driven, as mistakenly stated above. Back in the '90s it was introduced in lieu of MTBE, but now it's a green mandate chock full of renewable nonsense that in spite of mandates, tariffs, and subsidies is rejected by the market.

John Siebold

Click to expand...

John,
The Clean Air Act of 1990 requires states to monitor their air quality and report C02 emissions. Depending on the allowable emissions at that time, the states are required to submit their plan of reduction. The State of Texas has elected to eliminate the sale of non-ethanol fuel in high C02 areas as a solution. Of course politics are involved but it is indeed air quality driven. Where you live may not have enough C02 emissions to matter and vendors are simply taking advantage of the tax credits that are also available. I would much prefer non-ethanol fuel but unfortunately I live too close to one of the highest C02 emitting metropolitan areas in the country. If it was not air quality driven I could have my way...like they do in the midwest where the ethanol plants actually produce the stuff.

Iowa ethanal

I had been over the years watching the vangards flying on ethanal, the pilot I talked with said he burns 30 percent more ethanal for the same power settings than avgas.
That said if you decide to burn any gas with alcohol in it remember, your gascolator
is useless and any water that would have collected in the bottom will mix and go right through the mesh that water on its own would not. I had the misfortune of
running 10 percent through my 450 International tractor once. The glass turned yellow as the gasohol and water ran out of the carb mixed with a little gas. Engine started then quit a few minutes later with no possibility of a restart until fuel line was cleaned. No I did not clean the cup before I placed fuel in it as I could usually run most of the year with standard Unleaded and pick up a quater of the glass with water.
Thought about using Premium unleaded in my RV but only if I recieved the gas from
my local fuel supplier. He said he would test it for no alcohol and drop it off at the house in 55 gallon drums.

johngoodman said:

... The only law is that a sticker must be on the pump if the gas contains ethanol. ...
John

Click to expand...

There is no federal law that requires pump labeling for E10. There is no requirement in the federal RFS mandate that requires gasoline producers to blend ethanol into gasoline in ever increasing amounts through 2022 to label pumps as to ethanol content. The EPA overseas the federal RFS mandate, which is in EISA 2007, and they have no requirement for pump labeling, unless it is E15 for non flex-fuel cars, but they have not approved its use, only approved a waiver for it in 2001 and newer cars. All E10 pump labeling is governed by the states and varies. California has no pump labeling law for ethanol and essentially all of the gas sold in the state is E10. Oregon has a mandatory E10 law and requires pump labeling but Missouri also has a mandatory E10 law but does not have a pump labeling requirement. Go figure?

David-aviator said:

There has been a mind set against ethanol in airplanes since day one, especially within the STC process. EAA did a lot of testing of mogas to get the STC's approved and so has Petersen Aviation. But how much of it was burning E10? ...

Click to expand...

There is no "mind set". The tests were done by Cessna. This is the reference at the EAA web site: http://www.eaa.org/autofuel/faqs/ethanol_blends.pdf

If you don't want to read the superfluous material about state activity on ethanol mandates, the results are in Questions and Answers Section 6 & 11:

6. Will EAA be doing further auto fuel STC studies to add ethanol-blended gasoline to the STC in the future?

Answer: No. EAA, the FAA, Cessna, and others conducted studies ? they have all determined that a 10% ethanol and gasoline mix is not compatible with aircraft use. Further testing will not change the basic fact that to use ethanol-blended autofuel in your aircraft will require a total fuel system re-design costing well over $10,000 per aircraft.

11. What are the modifications I must make to my aircraft to be able to use ethanol-blended auto fuel?

In July 2002 Cessna engineers researched and produced a document called ?Evaluation of Ethanol-Based Aviation Spark-Ignition Engine Fuel.?

In this study Cessna noted that ethanol has the potential to produce up to 15% higher power outputs along with cooler exhaust gas and cylinder
head temperatures than 100LL. However, they also noted that to obtain those results required them to have a fuel flow 47% higher than 100LL.

Cessna indicated that ethanol-blended fuels are not compatible with airframe parts (aluminum, etc.), and fuel bladders and rubber parts (hoses, O-rings, etc.) ? the ?soft? parts of an aircraft fuel system. The report also indicated problems with calibrating capacitance-type fuel indicating systems, and long-term fuel storage issues (refer to question 6. above).

The Cessna team attempted to develop a solution to these issues, and stated the easiest solution was to raise cylinder compression ratios by installing taller pistons in each cylinder. This solution was not promoted due to the very high cost of the conversion and the years it would take for the FAA to recertify the engine with the new components.

Bottom line, EAA does not believe solutions available in today?s marketplace would be economically feasible for the average general/recreational aircraft owner.

sheepdog said:

I had been over the years watching the vangards flying on ethanal, the pilot I talked with said he burns 30 percent more ethanal for the same power settings than avgas.
That said if you decide to burn any gas with alcohol in it remember, your gascolator
is useless and any water that would have collected in the bottom will mix and go right through the mesh that water on its own would not. I had the misfortune of
running 10 percent through my 450 International tractor once. The glass turned yellow as the gasohol and water ran out of the carb mixed with a little gas. Engine started then quit a few minutes later with no possibility of a restart until fuel line was cleaned. No I did not clean the cup before I placed fuel in it as I could usually run most of the year with standard Unleaded and pick up a quater of the glass with water.
Thought about using Premium unleaded in my RV but only if I recieved the gas from
my local fuel supplier. He said he would test it for no alcohol and drop it off at the house in 55 gallon drums.

Click to expand...

Once again this comes down to annecdotal evidence and each of us must make the best informed choice we can. For me E10 works just fine. With my on board fuel flow monitor (proven to be amazingly accurate) I burn 7% more fuel running LOP to make the same cruise performance in the RV. This is running LOP.

I would suggest that any water in the fuel is perhaps more of a risk in a carburetted engine due to the increased surface tension of water potentially making it difficult to suck it out of the jet.

fuel injected motor does not suffer from this draw back.

I believe you must have gotten a LOT of water in your tractor's tank, you simply don't see cars pulled over by the side of the road due to water in the fuel. Maybe you were suffering from the extra surface tension issue I described above?

Of course all modern auto's are FI'd so maybe there is some evidence that carbs and E10 have a greater risk.

N1593Y said:

Answer: No. EAA, the FAA, Cessna, and others conducted studies ? they have all determined that a 10% ethanol and gasoline mix is not compatible with aircraft use. Further testing will not change the basic fact that to use ethanol-blended autofuel in your aircraft will require a total fuel system re-design costing well over $10,000 per aircraft.

11. What are the modifications I must make to my aircraft to be able to use ethanol-blended auto fuel?

In July 2002 Cessna engineers researched and produced a document called ?Evaluation of Ethanol-Based Aviation Spark-Ignition Engine Fuel.?

In this study Cessna noted that ethanol has the potential to produce up to 15% higher power outputs along with cooler exhaust gas and cylinder
head temperatures than 100LL. However, they also noted that to obtain those results required them to have a fuel flow 47% higher than 100LL.

Cessna indicated that ethanol-blended fuels are not compatible with airframe parts (aluminum, etc.), and fuel bladders and rubber parts (hoses, O-rings, etc.) ? the ?soft? parts of an aircraft fuel system. The report also indicated problems with calibrating capacitance-type fuel indicating systems, and long-term fuel storage issues (refer to question 6. above).

The Cessna team attempted to develop a solution to these issues, and stated the easiest solution was to raise cylinder compression ratios by installing taller pistons in each cylinder. This solution was not promoted due to the very high cost of the conversion and the years it would take for the FAA to recertify the engine with the new components.

Bottom line, EAA does not believe solutions available in today?s marketplace would be economically feasible for the average general/recreational aircraft owner.

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Any system re design on a certified aircaft will cost $10,000..We on the other hand are not limited to rediculously high costs and may build perfectly reliable fueling systems at low cost. Of course this means you either junk the mechanical fuel pump like I did or rebuild it with alcohol reistant components.

As to burning 47% more gas to make 15% more power..well OK..but why do you want 15% more power in any case..Like I said in an RV at cruise LOP its 7%..actual data in an actual RV.

Not aluminium etc...not seen any corrosion so far.

Hoses etc?..Use teflon lined and there is no problem...

The surface ension of water getting into a carb might be an interesting issue.

E10

Just tore apart my portable compressor carb and it was corroded so bad that i had to buy a new carb. I even put stablizer in it.So your fuel better be mighty fresh and burn it off but I don't want that stuff in my plane carb.
I can buy clear gas in Oregon just over the border.Should have used it in the compressor!!!!

Aluminium alcoholates

I burn 7% more fuel running LOP...

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Even that increase is a bit surprising. A 10% etoh - gasoline blend has about 3.3% fewer BTUs. BTUs are what make the fan go round...

Regarding corrosion, I did a little research on "aluminium alcoholates". There are quite a few primary research papers on this subject. Seems that the big concern is with liquid etoh and hot aluminum of the wrong alloy composition. Vapor blend with 10% etoh blowing through the cylinder head ports is not too likely to cause any problem, even if the heads aren't the "correct" alloy choice.

The alloys with problems are ones that contain copper. Analogous to the wrought alloy type 2024 that is common to RV structural parts, casting alloys of type 2xx.x contain copper.

Casting alloys of 4xx.x (silicon alloy) or 7xx.x (zinc alloy) are much preferred for corrosion resistance.

So, one would expect that the automotive environment would be a good place to discover this type of corrosion problem. Sure enough, Holley carburetors went through a "recall" in recent history. It seems that they used the "wrong" alloy for float bowls, and paid the price for the mistake. So it doesn't surprise me that in the real world, some carbs have
problems and some don't. Your low cost vendor for cast aluminum trinkets is likely the third world, and not too fussy about alloy choice.

I have run 87 mogas for nearly a thousand hours without issue in my RV-6. Most of it E10. Last April my -6 was one of the aircraft destroyed at SNF, and I bought the salvage back and will be rebuilding it after my Rocket is finished.

Tonight as I was out shopping with my wife and kids I thought I should check the tanks this evening for any corrosion. The last fill up was mogas, before the tanks were drained by the SNF recovery mafia.

So my wings have been sitting for almost 10 months. I opened one of the tank access panels in the root and was almost overcome with the stink of stale mogas. Holy moly it smelled bad. But as I looked inside I noticed everything I could see was perfect. No corrosion. Nada. Nothing. Zip.

I also checked the fuel lines in the fuselage for any corrosion. Nothing wrong that I could see.

A few months ago I sold the carb and before I sold it I opened it up and inspected it. Again, Nada. Nothing. Zip.

Rocket Bob's Carb

I have about 15 hours on Bob's old MA4-5 in Miss Sandy, and no issues so far. I do run 100LL at $ 4.87/gal when it's available otherwise I pay the going rate. I did flush my tanks just prior to wing attach back in November with 91 octane marine (no ethanol) gas purchased at a nearby marina up on Lake Lanier her in NE Georgia. 52A is expecting to install Mogas tank this spring to sell 91 octane ethanol free fuel at about $1 /gallon under the 100LL price. I think he will do a land office business as most 100LL in the Atlanta Metro area is well over $6/gallon. Just my .02

frankh said:

I think this all points to lack of evidence..I.e there just arn't that many airplanes running on E10.

So we are really left with a mixture of reports and personal experience.

As for my personal experience I have about 400 hours an almost exclusively E-10. My airplane resides in a hanger and the premium gas sometime sits in the tanks for a month or two when I'm busy and don't get to fly much..Note I always do at least a half hour round the patch once a week.

Every year I dismantle the steel fuel hose fiting at the FI servo and drain the tanks.

My system is designed to pump Ethanol (i.e no mechanical fuel pump, AFP FI system and o rings changed for flourosilicone in the tank drains).

My personal experience is:

1) No corrosion anywhere, in the tanks or steel fuel fittings. No products of corrosion noticable in filter screens.
2) No seals failed and certainly no vapour lock (it was designed this way after all)
3) No noticable water absorbtion..Not sure how I would know anyway..With FI the surface tension changes you might see with E10 in a carb (if any) are irrelavent.
4) No bad gas as far as is noticable.
5) recent boroscope check revealed a clean top end with no signs of damage (I would hope not!)
6) Running LOP at 24*24 the gas consumption rises to about 7.6GPH vs 7.0 for stright gas or 100LL.


Bottom line..from my experience so far I have no intention of ever running 100LL if I can avoid it. I would avoid E10 but only for the reason its a rip off!

Frank

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Thanks Frank for the first hand experience. Based on your input, shall I assume you had no compatibility issues with fuel tank sealant and E10?

So far no..I checked with the manufacturer and they told me it was compatible.

I have a few paint bubbles like other quick built tank owners but nothing that looks any different.

I will need to look at prices of ethanol free mogas, today I filled up my cans at 3.67.. ad 7% for extra burn equals 3.93 effective cost.

Depending on what they sell straigh gas for in Corvallis may make it not worth bothering with 10 ETOH.

Of course Rocket Bob uses 87octane (car) regular and I use premium..I just haven't had the courage to drop to 87 Oct yet..

I put E10 in a Honda portable generator. After sitting all winter the generator would not start, and when I disassembled the carburetor I found extensive corrosion in the float bowl, which had clogged up the jets. I cleaned the carb and have since used non-ethanol gasoline, which has not caused a repeat of this problem.

Also had a dirtbike that required a carb cleaning after leaving ethanol gas in it over the winter.

No more ethanol gas for me in anything that doesn't get used regularly. Too much potential for corrosion.

Vapor Lock Data Point

I decided to test out my new oxygen tank and take my plane up to 17,500' the other day. At about 13,000' I started to get fuel pressure fluctuations. Turned on the electric fuel pump and everything settled down. Kept turning boost pump on/off as I climbed to see what happened. At ~16,000' the engine would lose power and stop working on just the mechanical pump. The electric pump would bring everything back to normal on up to 17,500' where I stopped.

Fuel - 100% E0 93 octane
OAT - ~-10F @ 15,000' (It was a cold clear day and ground temps were ~35F)
Powerplant - IO360, FI, Lightspeed EI, 1 mag

I suspect I was getting bubbles in the fuel lines which is what caused the fuel pressure to drop off. Turning on the boost pump would provide the extra pressure to condense the fuel back to liquid. At least that's my best guess at this point.

Anyway, I'll probably test again with AVGAS to see if I see any similar conditions. Just wanted to pass on the data point.

Greg
RV-7

hoses-

If I can throw this out there---(IN my real job)--- Over the past several years, the auto makers have been switching from 'rubber' fuel hose assemblies to teflon with either stainless braid, or kevlar type braid. Some even use a thermplastic type liner. Many rigid tubes have gone from steel to stainless.
On the older hoses that I see that have been using an ethanol mix, the hose liner has degraded to the point of failure in some instances. When you cut the hose apart and inspect the liner, you can literally rub your finger on the liner and get the black liner substance on it. In some cses, the liner has formed cracks, and begun to separate. These liner pieces get into filters, and if farther up at the engine, get into injectors. Bad deal.
So, to fix the issue, the auto manufacturers have gone to a thermo, or a teflon liner with various reinforcement and covers. Now, I dont know about the makeup of mogas, but I see what it does to hoses. I would assume that if you use it in your plane, that you may see the same things. Of course, your mileage may vary.
If you've been using mogas with ethanol and a rubber lined hose like 303 or 701, I would suggest the you really inspect them well at your conditional.

On another note just for informational purposes so you can understand where I'm coming from---We dot ALOT of aluminum Air Conditioning tube assembly repairs. It is very common for vehicles to have tube leakage from internal corrosion. We have seen that the PAG oils and additives mixed with R134a freon will corrode the aluminum tube from the inside out, especially where the tube is secured by a rubber clamp, or has a insulating sleeve around the tube. It develops as pin holes, and gets worse from there.

I say this because because several of you reported some corrosion using mogas with ethanol. If you have aluminum lines for fuel, and you have seen corrosion in your carbs, etc----check your tubing.

Again--just relaying what I see everyday ( in my 'real' job), and not what may be happening to you.
Tom

Greg I can tell you right now the symptoms you saw are classic vapour lock.

So now lets say you try to take off on a really hot day at a high elevation airport..Your fuel flow is at a maximum..and your electric fuel pump quits on take off.

Your mechanical pump could immediately vapour lock and your engine might quit.

In other words under the most critical conditions you might as well just have a single electric fuel pump cus thats all you got anyway!

Thats why I run redundant electric pumps and have one away with the mechanical pump.

You could improve the situation by using a cooling blast tube and shroud on the mechanical pump.

Its a bandaid to a poor hydraulic solution but if like most flyers your married to the mechanical fuel pump its better than nothing.

$7.79 gal 100ll

At the FBO at the Aspen airport, the 100ll is getting close to $8.00 gallon. Of course, regular car gas is about $4.50 in town. Nothing is cheap in Aspen!

When flyinmonque came over to Rifle, CO to give me a ride, I believe 100ll was about $5.50 and car gas is about $3.50. In this part of the country, it makes you think pretty hard about using car gas.

100 hours per year at 7gph average = $3850 (100ll @ $5.50)
100 hours per year at 8gph average = $2800 (91 mogas @ $3.50)

The $1000 per year is just about the point where it makes sense to consider mogas. of course, it won't be available at every place you land, so savings would less. I don't know anything about mixing the two types of fuel.

I did have a bad experience with E10 in my generator last winter. I guess the problem was actually early spring when I needed the generator because of a power outage. I tried to start it - no go. I looked in the gas tank and it was rusty with quite a bit of corrosion. I had not put Sta-bil in the gas. I don't make that mistake anymore.

I am still undecided on using mogas or not when I am finished with my build. I did use it in the Piper 180 I used to fly, but we didn't in the C 182. It would sure be a big help to all of us if they would stop the political crapola and get the E our of the gas!

Frankh,
I never thought I'd hear you worry about the electrical fuel pump quitting.

N427EF said:

Frankh,
I never thought I'd hear you worry about the electrical fuel pump quiting.

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I assume there is a touch of sarcasm in that statement..

But for the uninitiated.. An electric fuel pump is a component that may fail like anything else. For lightweight and critical components we try our best to avoid just having one of anything.

Thats why even though I have two electric fuel pumps they are wired independantly, two circuits, no common switches, fuses or wiing between the two pumps.

In my carbed airplane I used two batteries..the second battery had the second electronic ignition and the send fuel pump wired to it..Nothing else.

In the FI'd RV I took the single battery, dual alternator approach, based on the service history of the Odyssey battery.

My point is under certain circumstances the standard RV fuel system is a single electric fuel pump system, particularly running mogas.

Thats too large of a personal risk for me, and as I refuse to pay for 100LL unless I have to (and the mech pump is alcohol intolerant) that made the choice of fuel system obvious.

Others have an opposite view an choose to run 100LL..I have no argument, its time tested. I just think there is a better way and there are a number of coverts to the dark side that haven't fell out of the sky yet..

rockwoodrv9 said:

When flyinmonque came over to Rifle, CO to give me a ride, I believe 100ll was about $5.50 and car gas is about $3.50. In this part of the country, it makes you think pretty hard about using car gas.

100 hours per year at 7gph average = $3850 (100ll @ $5.50)
100 hours per year at 8gph average = $2800 (91 mogas @ $3.50)

The $1000 per year is just about the point where it makes sense to consider mogas. of course, it won't be available at every place you land, so savings would less. I don't know anything about mixing the two types of fuel.

I did have a bad experience with E10 in my generator last winter. I guess the problem was actually early spring when I needed the generator because of a power outage. !

Click to expand...

I found running LOP that the fuel consumption between straightcar gas and 100LL to be identical for the same speed.

That makes your analysis favour mogas even more.

Using the AFP FI system and no fuel pump I think we can put the corrosion question to bed..its a non issue.

Rubber parts are an issue, so its questionable if the mechanical fuel pump should be used with E10.. Of course hats also a non issue in my case.

As to mixing the two types of fuel..this has been tested extesively..Its a non issue.

Mogas user

Yes Frank, little sarcasm there.

Trying to keep myself from commenting before accumulating any real experience with mogas E10.
But here is what I found so far:
RV-10 IO-540 8:1 compression AFP injection LS one side mag on the other.
AFP boost pump and mechanical fuel pump with cooling shroud and constant flow return line.
I am using mogas in one tank and 100LL in the other for cruise.
I have thought long and hard about the use of mogas in a brand spanking new 540 but I am convinced based on real live evidence mostly from RV pilots that the use of ethanol laced mogas is not a problem.
The mountain of evidence against the use of this fuel can be summed up as follows.
Studies conducted by universities and major manufacturers simply cannot approve of this fuel, because it may not be fully compatible in all regimens of flight and the consequence of having to re certify an aging GA fleet is simply not feasible. In a nut shell, if the fuel does not perform at the fringes of the performance envelope it is deemed, not compatible most certainly if the plane has a rubber fuel bladder.

For Rvs however and most of how I fly generally, it works very well.
I don't fly up in the flight levels and if I need the boost pump on, to keep the engine running up there, it'll be ok with me. For take off and landing the boost pump is on anyway.
For now, I can only use mogas at my home base after hauling it to the airport
and for flights were I need to refuel away from home its 100LL as it is for everyone else since nothing else is available on airports.

One thing I noticed right away, the engine runs smoother on mogas.
My injectors have not been tuned yet and running LOP on 100LL makes the engine run somewhat rough and rumble a little.
On Mogas however, I am astonished to be able to lean way past peak and have a very smooth running engine with temps EGT <1250> and Cyl temps around 300F. FF 10GPH. Switching to 100LL in this condition, the engine will hardly run anymore.
The diaphragm in the mechanical fuel is my main concern but the total exposure to ethanol fuel would be about 90 hours for 1000Gallons of fuel used. The airplane sits with avgas since I flush the system for landing.

The cost of avgas is not the only consideration for me but weaning myself
off the emotional attachment to the avgas tit is.

TS Flightlines said:

....If you've been using mogas with ethanol and a rubber lined hose like 303 or 701, I would suggest the you really inspect them well at your conditional....


Again--just relaying what I see everyday ( in my 'real' job), and not what may be happening to you.
Tom

Click to expand...

Tom,

Thanks for the heads up from one who has first hand experience.

My experience with 303 hose and 100LL years ago was not good.

Aeroquip probably fixed the problem but when 100LL first came out, it destroyed 303 hose. I had the cowling off one day on a LEZ and was checking something with the fuel pump on, a Facet running at about 3 psi, and the 303 hose was leaking full length like a sieve. The inside was mush.

Like I say, the composition of the inner lining probably has been changed but it sure was an item to check on a condition inspection then. Mogas had nothing to do with it. It was one of the 85 or so ingredients mixed up in 100LL.

Mogas

Boy I'm glad I live in the midwest (Near Grand Forks. ND). Just filled my 1000 gal tank with $4.20/gal 100LL. Sometimes there are benefits to live in small town USA. Problem with mogas with or without ethanol is shelf life. Not so bad in the winter(North Dakota winter) but in the summer heat the gas will start to look like orange juice in a couple of months. Less than that if there's water in the gas. If you fly often mogas is fine. I wouldn't let it sit for very long.

David--its a scarey feeling when you can rub your hand on a hose and have the black color of the outer cover get all over your hands. And this is with automotive applications. Aircraft applications would scare the **** out of me.
Even some of the really good suppliers of automotive rubber hose, Earls, Goodridge among others, state that they dont know what additives are in the fluids we use, and if we arent sure, then they recommend teflon.
I know this first hand, and Mike Starkey and others can appreciate this: I build assemblies used for the Jaws of Life systems for our local fire departments. They switched to a different manufacturers fluid, which is essentually Skydrol. They had a blown hose (someone rubbed it against the pump muffler and POOP). Well this stuff is bad for your skin. All I did was pick up the hose and noticed a funny feeling in my hands. Yep----get them washed off ASAP, and double surgical gloves. They also were using a standard hydraulic hose whose liner was NOT compatible. It was literally coming apart. Could have been a real bad deal if it had sprayed everyone at a wreck scene.

My point is---we dont know what 'other' additives the gas companies are putting in the fuel you are using. My suggestion---for what its worth--is if you dont know, of have questions, go with teflon. If you are currently using 303, or 701, look at them closely. If you have them off (for some other reason) be careful not to flex them, but at least shine a brite lite down the hose and take a look if you can. I say not to flex it, because like teflon, 303 & 701 can also take a set, and 'if' there was an unseen issue like a liner beginning to crack, you would not know it. Flexing the hose could damage it, and on re-install have an issue. Or at Altitude.

Again, my suggestions only, and what you have may not apply. I just know what I've seen.
Tom