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Let's see 20 hours per year at 4 gallons per hour is 80 gallons per year. $2.50 savings per gallon is $200 per year savings. Someone with 50 hours per year saves $500 per year to put toward hanger rent or insurance. Sounds good to me.
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Dana, as I said I am not aware of any valve seat issues caused by leaded fuel. I think Stellite valve seats came along to deal with problems of exhaust valve seats when overheated, like in turbocharged planes. I wonder if this might have been when we went to lower lead fuel like 100 ll. I am not sure.
And my math left out a step, if you fly 20 hours at 4 gph and save $2 per gal, that's 160 per year or at $2.50 saving per gal is $200. I wouldn't take a chance on fuel system damage from avgas that might have ethanol for that amount. Now if you did something like fly jumpers in a Cessna or pipeline patrol for hundreds of hours, then savings might add up.
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As for insurance, I wonder if most policies or any would cover a plane using car gas? It might depend on if you had an STC or if that model of plane or engine was tested and approved for auto gas.
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Of course the FAA has now authorized the use of VLL or very low lead gasoline according to the latest reports.
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Folks, their are volumes of information on this issue in many places, for instance our blog at General Aviation News, http://www.generalaviationnews.com/c...inion/gafuels/ Just a few excerpts from there: (a) there are 14 models of Bonanzas whose engines are approved for autogas; (b) Lycoming's use of Bendix fuel pumps on the engines in Mooney's and other aircraft are highly prone to vapor lock, the reason autogas STCs do not exist for them; (c) insurance will of course cover any FAA-approved TC or STC for autogas; this is a non-issue; (d) 100VLL is essentially the same as 100LL, this approval will really change little in terms of opposition to leaded avgas; (d) Nearly all new generation engines (Rotax, Jabiru, ULPower, D-Motor, Lycoming, etc.) are designed to run on premium, ethanol-free, lead-free autogas. Why? Because once outside the US and Canada, Avgas has disappeared or is very expensive; (e) Italy's Tecnam, the world's largest maker of light aircraft, has an all-autogas fleet of airplanes, from 2-seat LSAs to 11-seat twin-engine commuters; (f) Avgas producers are disappearing, we're down to 8 in the US and they are all west of the Mississippi; ExxonMobil announced their departure from GA last month. In the future, there will be two primary aviation fuels, autogas and Jet-A. Avgas will be around for awhile as long as the market will support it. This is tough news for those who need a 100 octane fuel, but good news for the 90% who don't. Switching to autogas will not only end our problems with lead, but will save us millions, and perhaps help reverse the overall decline in sport aviation. On lead in valves - this is a huge problem for low compression engines, since most piston engines were never designed for the high levels of lead in 100LL or 100VLL (which is really no different than 100LL). My old Conti C-145 in my '52 C-170B ran great on 91+ AKI ethanol-free autogas. When Amoco stopped selling it (thanks to BP's draconian cost-costing after the merger) I was forced to switch to avgas, which is when the problems started. Sticking valves, a new jug, lead on the plugs, sludge on the belly, an eventual in-flight engine fire and loss of the aircraft, fortunately noone was hurt. Note too that Jabiru and Rotax strongly recommend against ethanol blends and leaded fuel, since these engines are (like most newer aircraft engines) designed to run on premium, ethanol-free, lead-free autogas.
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It is a pretty big jump to say that 100 VLL is "no different than 100LL". What is the practical , not theoretical proof of that? How many hours or years in how many types of aircraft engines IN ACTUAL USE, does 100VLL have. Just because the FAA or whoever may allow or even approve 100LL is not very convincing. A few years back an approved engine oil, I think it was Mobil One ruined many aircraft engines, and the maker had to pull it from the market and pay for lot's of overhauls. To be fair, I think they did that ok. .So just because it works in the lab, sounds good to academic types, and works in autos does not make it the same as something proven over years of use.
As for an engine fire in a C-170 having anything to do with avgas use, I really doubt it. Can you produce any NTSB/FAA report that lists avgas use as the cause of an accident in any C_170 or similar production plane with a standard aricraft type engine? If not, your account sounds a little like something from a Michele Bachman campaign. My friend flys his C170 or 140 ,can't recall which here from Denver often and on avgas, just like his T-6 or his Be 36 TC.
As for engine practice in Italy, I don't know much about that, but doubt if it has much to do with the U S, We probably have more gen av in one state in the U S than all of Italy.
As for Mooneys, I don't know much about their fuel pumps, except mine always worked for the 15 years or so in the M20 C and the M20 J I owned. I didn't have any problem with vapor lock that I recall. My Bonanza is hard to start when the engine is warm and on hot days, unless the boost pump is on. Seems that is vapor lock.
I have no financial stake in avgas, except as a pilot and owner of a couple of high power planes that need at least 100 octane performance, and I have no stake in auto gas except as owning some stock on gas companies.
I don't have any devices or STCs to sell.
I have heard that many of the new type engines like Rotax or Jabaru that came from a non aviation background like snowmobiles or cars, operate fine on car gas. But that is not a major part of aviation in the U S, at least not yet.
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If you wanted to use auto gas in a normal engine airplane, say a Cub or 182, not 2 stroke auto type and you are going to buy the gas at a service station, since only a few FBOs sell auto gas, How do you know it does not contain ethanol? Can you rely on the markings on the pump? Or can you rely on state regulations? To be safe do you have to have a test kit and test each batch of auto gas?
Are there some areas of the country or states where auto gas at airports is becoming more common?
If you do get gas with ethanol in it, how long before a problem arises in a normal fuel system, again talking about standard aircraft engines, not Rotax etc.
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To be completely certain there's no ethanol, I guess you have to test it. Otherwise, you have to rely on the integrity of the seller that it's properly labeled, and perhaps state laws regarding labeling. But that's true even of avgas... I found myself and my T-Craft in a farm field years ago because of contaminated avgas... after that, I stopped buying avgas from the local FBO and ran only car gas (this was before ethanol), except when I went cross country.
Ethanol has four major problems: It attacks seals not made with compatible rubber compounds (or fiberglass tanks not made with compatible resin), it absorbs moisture which can cause corrosion, it runs leaner (especially a problem with 2-stroke engines), and it delivers less power. I would be very leery of an older aircraft engine's seals; I don't know if replacement components used on more recent overhauls use the newer compatible rubber compounds.
Note that Rotax allows up to 10% ethanol now... and with the growing LSA market, these engines are becoming a significant part of aviation.
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Bill:
(1) The EAA has stated that 100VLL is the same as 100LL, it seems that Avgas has in reality had the same levels of lead as the new 100VLL standard for some time, read the article here: http://eaa.org/news/2011/2011-09-15_100vll.asp
(2) I flew my C170 for about 600 hours in 5 years, 150+ hours in the year I lost it to a fire. After switching from autogas to avgas I started having problems with valves sticking, lead deposits on the plugs and the usual lead sludge on the belly. Ask anyone who flies a plane with an old, low compression engine and they'll tell you the same stories. The wreckage of my plane showed a gaping hole in the head where a valve had once been, an indication of a stuck valve. The NTSB has never made a final ruling and probably won't as there were no injuries and minor property damage other than the loss of my plane.
3. On Italy - you need to get out more. Sport Aviation is alive and well in Europe. When you compare regions with similar climates, some of these countries have more pilots and airplanes per 1000 residents than we do in the US. Tecnam, founded originally as the old Partenavia company in 1948, is the world's number one producer of light aircraft and a majority of their planes are used outside Italy. They are one of the most popular aircraft you'll find today in US Sport Pilot flight schools. Their P2006T twin Rotax is an amazing plane, burning a mere 9 GPH autogas total. They are now working on an 11-seat twin under contract to Cape Air, to replace the companies fleet of Cessna twins.
4. Mooney - my comments on vapor lock were for autogas, not avgas. But vapor lock does occur with avgas in many aircraft under the right conditions.
5. Rotax, Jabiru, etc - 70%-80% of all piston-powered aircraft today run just fine on 91AKI autogas. Those needed 100 octane fuels are in a small minority, but this does not mean they should not have a fuel, too. Let's not force however the majority of aircraft owners to buy more octane than needed. The LSA sector is the only one growing in GA, and these aircraft generally use engines designed for autogas, that's a fact.
6. Ethanol-free - One must check any fuel you buy at a gas station for use in an engine not made for ethanol. That includes boats, chainsaws, law mowers, in total some have estimated 650 million gas engines are negatively affected by ethanol. Do not trust a label on a gas pump.
7. Rotax - had approved up to 10% ethanol but Rotax owners are strongly advised to use 91+ AKI ethanol-free, lead-free autogas, not an ethanol blend, and not leaded avgas. Jabiru recently rescinded past approval for E10 in their aircraft due to evidence of damage to fuel tanks. They require ethanol-free now.
Where to find autogas:
At retail stations, use this list: http://pure-gas.org/
For airports, use this list: http://www.flyunleaded.com/airports.php
You'll see from the first list the rapid rise in listings:
http://pure-gas.org/chart
There are more airports selling autogas in 2011 than in past years, and you'll see a continued rise. In contrast, FBOs have been dropping 100LL avgas steadily as many focus solely on Jet-A.
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Interesting thread. I only use part 100LL in my 56 Chevy, as it was designed for lead to lubricate the valves. I would have suspected more users to be familiar and comment with the Rotax specs of using MO-GAS vs 100LL to maintain a 2000 hour TBO. My 912 ULS 100hp has to have twice the oil changes and spark plug changes with 100LL and is more particular of what oil I use than with mo-gas, not to mention the price. $1.71 difference in my area. I only use 100LL in it if I am dry and a ways from home. There are a few stations in Oklahoma that have 91 pure gas close to my ariport, so I haul it. I am concerned of the quality, as we all should be (I once found residue of a bad pump seal chewing up in 100LL from my FBO in my Cherokee 235). I check for ethanol content with a small tall olive jar with 1 inch of water, if the level of the water changes, you have ethanol. You can look up how to do this if you are not familiar with this. I pump my mo-gas into my tanks with a 7 micron filter, anything smaller will flow right through the motor and out the exhaust. (filter still seems clean after more than 800 gallons) Just be sure to buy from a busy station, his fuel will be fresher as it would not have been in his tanks long. If there had been contaminates (unlikely) they probabally already have been flushed out, like your FBO, right?.
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