Lycoming's View: Pump Gas is Not Mogas

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For decades, general aviation has been operating and designed around a single fuel – 100LL. Now environmental and economic pressures are driving the search for an unleaded alternative. Lycoming firmly believes that an equivalent performance unleaded aviation grade replacement for 100LL is the best total solution for our industry overall. We also know that using automotive blends in aviation is possible for certain engine models if you put the correct controls in place on the fuel. Lycoming's consistent objective is to give our customers as many fuel choices as possible while still maintaining airworthiness.

In the following three guest blogs, Lycoming specifically addresses the topic of automotive fuels for aviation, including our approval to operate certain Lycoming O- and IO-360 engines using an automotive specification fuel. Lycoming strongly recommends a thorough review of the latest revision to Lycoming Service Instruction 1070, "Specified Fuels."

Lycoming is well aware that other aviation equipment manufacturers have allowed "pump gas," in some cases with ethanol. In the details they provide warnings and cautions addressing some of the issues we raise in these articles, leaving it to the operator to assess risk in using a fuel where they do not know the core properties other than octane. We do not agree with that approach.

Two terms are used repeatedly throughout this series: "pump gas" and "mogas." "Pump gas" refers specifically to fuel that conforms to the ASTM D4814 or Euronorm 228 specifications for automotive fuel and is available for retail purchase at automobile filling stations. "Mogas" refers specifically to fuel that also conforms to the ASTM D4814 or Euronorm 228 specifications, but controlled and labeled differently such that it is "fit-for-purpose" for aviation.


Part 2

Automotive fuel from the pump is not the same everywhere you go. There are summer blends, winter blends, geographical blends within the seasonal changes, varying levels and types of oxygenates (not just ethanol) and when tanks are switched over a mixture of "in between."

The pump labeling is accurate for octane, and in some parts of the world, the maximum percentage of ethanol. It doesn't tell you everything you need to know to make "pump gas" fit-for-purpose for aviation and it's not just about octane and ethanol. We need to control a wider range of fuel properties for aviation. Your equipment, your life and the lives of your passengers depend on it.

Let's walk through exactly what Lycoming did in authorizing automotive gasolin –mogas- for our engines. It's also suggested that you read Section B of the latest revision to Lycoming Service Instruction 1070 – and read it carefully.

First, notice that we specified 93 AKI as the octane level. This octane level provided the required detonation margin without modification of our engine FAA Type Design allowances, including cylinder head temperature limits. 93 AKI is "Super Premium" fuel. That AKI rated octane is what is needed to achieve the exact same power performance on the approved engines as 100LL avgas. 93AKI is produced worldwide, but not necessarily distributed worldwide.

Next, Lycoming limited vapor pressure to Class A-4. This was done to prevent vapor lock and A-4 was chosen as it overlaps with avgas properties. The Class A-4 convention arrives from the U.S. Environmental Protection Agency's influence on the automotive gasoline specification and the need to control emissions on ground vehicles. The automotive fuel spec has a method that allows us to control when vapor lock would occur and lends predictability to fuel evaporation through all phases of the aircraft operating envelope.

Ground transportation gasoline-heavily influenced by EPA-controls vapor pressure for emissions, startability and driveability on a seasonal and local geographic basis. Vapor pressure is not labeled for retail pump gas, but is controlled via the wholesale distribution chain. To make fit-for-purpose aviation mogas, you need to control vapor pressure and you need to know that it matches what your equipment needs.

No ethanol. Most assume that the restrictions on ethanol are related to corrosion. That is just one factor.. The other equally important parts are (a) that the automotive gasoline specifications allow vapor pressure to rise outside of the base control limits as you add ethanol and (b) ethanol reduces the energy density of the fuel, increasing fuel consumption.

Lycoming restricted ethanol more for vapor pressure control and fuel burn rates than corrosion. When you add ethanol, at certain percentages, the automotive fuel spec vapor pressure is allowed to increase. Fuel consumption rates increase from what the POH may indicate as you add ethanol because the energy density drops. Retail pump gas is not labeled for exactly how much ethanol or oxygenates are included--maybe a maximum in some of the United States --thus you do not know if it is matching what your equipment needs and consistent with POH performance curves. To make fit-for-purpose aviation mogas, you need to control the exact amount of ethanol and you cannot allow ethanol inclusion to grant a "bye" on vapor pressure.

Lastly, in approving mogas, Lycoming locked in the revision of ASTM D4814 to 09b and EN228 to 2008:E. Automotive specifications change frequently, almost yearly, in response to changing environmental regulations and political mandates such as ethanol inclusion. Freezing our mogas specification in time gives refiners a fixed standard and one that matches against the stated performance of the engine.

Predictability. Lycoming is well aware that other aviation equipment manufacturers have allowed pump gas, in some cases with ethanol. Notice that in the details they provide warnings and cautions addressing the issues we have raised, leaving it to the operator to assess risk in using a fuel where they do not know its core properties other than octane. We do not agree with that approach.

Summarizing Part 2 of this series, the Lycoming approval provides details on how to specify a fit-for-purpose aviation engine fuel from fuel that is designed to start and run ground transport engines. The controls we have placed on the fuel are necessary for engines in the currently existing fleet that were designed and certified for operation with avgas. Yes, you can maintain performance ratings on some engines. Yes, the Lycoming mogas might be in the tanks at your corner market or local gas station. No, you cannot determine if the retail pump gas is controlled as it needs to be for aviation because filling station pumps do not provide the information needed to match it to mogas requirements.

Yes, it is produced under existing ASTM and EN automotive fuel specifications and can be ordered wholesale, but we do not believe that it can supplant the 100LL avgas that is widely distributed already.

What our mogas approval really says is that using automotive fuel blends in aviation is possible for certain engine models if you put the correct controls in place and those controls are not in place for pump gas. It's an option to consider that would eliminate lead emissions and bring the potential for more fuels flexibility to customers, who would still need an airframe TC or STC to operate.

Airworthiness by Design. In the next article we'll go deeper into Lycoming's motivation to approve mogas--a low-grade aviation fuel from automotive blend stocks.

Comments (51)

Again, an excellent piece. Thank you Michael

Posted by: KRIS LARSON | August 10, 2011 1:03 AM    Report this comment

Great to see Lycoming endorsing autogas after three decades of its successful use in thousands of Lycoming-powered aircraft under EAA & Petersen STCs. Perhaps it was this good experience that convinced them to revisit the issue?

A few comments:

93AKI - A quick review of the Pure Gas web site shows that 93 AKI is widely available in the US. About 25%-35% of gas stations in a given state have it, which means it is available at terminals. Most engines TC'd or STC'd for autogas only require 91+ AKI, many only 87 AKI.

Vapor Pressure - If you look through the entire OPIS Padd report, every terminal sells 9 psi RVP, or LRVP which is 7.8 during the summer. Vapor Pressure does not seem to be a big issue for autogas users based on what I have heard. Vapor lock does though occur in aircraft burning Avgas under certain conditions, happened to a friend of mine flying a Rotax 912 ULS - powered LSA this summer at relatively low altitude. One needs to be aware of the potential, regardless of the fuel being used. RVPs of 12 are unheard of these days due to modern electronic ignitions in vehicles that can better deal with lower volatility of low RVP fuels.

Posted by: Kent Misegades | August 10, 2011 7:49 AM    Report this comment

cont'd -

Ethanol - Could not agree more! Stay away from the stuff. Luckily, terminals will always have ethanol-free since ethanol may not be pumped through gasoline pipelines. This does not mean that all terminals have premium clear, what we call autogas.

Pump Gas - while experiences of pilots buying quality, ethanol-free autogas at pumps has been very good since the FAA first approved it as an aviation fuel in 1982, ideally airports would obtain it from terminals where there is more control, and from a reputable fuel transporter. Same holds for Avgas of course.

Overseas - It would be interesting to know from Mr. Kraft what Lycoming is seeing outside the US. How is the aviation fuel situation there, and what is the quality of autogas? He mentioned that the Nigerian Air Force needed autogas approval for their Lycoming-powered aircraft. Does Nigerian autogas meet his specifications? Perhaps this is in Part III of this series?

Posted by: Kent Misegades | August 10, 2011 7:50 AM    Report this comment

"Most assume that the restrictions on ethanol are related to corrosion."

Ethanol was never fine in cars (until cars had modern "positive pressure" fuel tanks). Aviation fuel tanks are still vented to atmosphere. That's a huge gotcha for any vehicle since ethanol rapidly absorbs water absorption and easily evaporates.

The technology for a more mainline gasoline has always been there for light piston planes. There just has no will to promote cheaper fuel by the alphabets in aviation. Even today they are pushing for more exotic, more expensive, and ultimately unattractive by refiners.

Posted by: Mark Fraser | August 10, 2011 8:08 AM    Report this comment

Mark, bingo.

The good news is that autogas has been approved years ago, most new-gen engine makers approve it, and there is a good supply of it at terminals. FBOs who sell it report the same margins as for avgas. It is one of those rare occasions where aviation can take advantage of an enormous volume production, sharing costs with literally billions of other people.

Posted by: Kent Misegades | August 10, 2011 8:28 AM    Report this comment

I fly a CTLS with a Rotax 912 engine which allows 10% corn crap. In past when I could get 91 octane no-ethenol, real gas I got better performance. Problem today is the "do-gooders" insist on putting ethenol in the gas--real gas is unavailable. Good luck finding the real stuff!

Posted by: Kenneth Nolde | August 10, 2011 8:33 AM    Report this comment

Ultimately, if you want to grow the fuel market, you need a reliable supply of airworthy fuel that the seller/distributor can feel comfortable dispensing without worrying about poor quality and liability.

To make it all work, and to provide certainty about the specification, the product that Mr. Kraft is talking about will need to be segregated from the rest of the stream, and then feed into an aviation supply chain with similar controls to what we have in place now (grade dedicated trailers, aviation QC procedures, laboratory analysis, etc.)

At the end of the day, segregation and control costs money, especially when you have an overall market that is the size of a pimple on the a$$ an elephant.

When it is all said and done, will this "magic bullet" mogas fuel really be less costly at the FBO fuel pump than 94UL, the product everyone was talking about last year? How much cheaper will it be to today's 100LL?

When aircraft crash, people die. No pulling over to the side of the road. Ease up on the standards, and you risk a rash of fuel related accidents. If that happens, the insurance companies will stop insuring, and the FBO's will stop pumping.

Sure, if that happened the old timers and hobbyists will continue to bring the fuel to the airport in 5 gallons jugs. But, the remaining pleasure, business, and commercial users will exit the market if they can't get aviation fuel. These are the folks that account for the vast majority of sales of Avgas today.

Posted by: DAVID COLEMAN | August 10, 2011 9:01 AM    Report this comment

Kenneth, check the web sites Pure-Gas & FlyUnleaded for lists of retails sellers and airports with ethanol-free autogas. Ask those in your area who their supplier is, then work with your airport to have it delivered. All one needs is a small tank or trailer for storage, there are plenty of excellent military surplus ones for little money. The entire biofuels industry is a train wreck in progress and I expect changes to the mandates in the next year or so. Still, ideal would be an autogas tank at every airport, not only to help FBOs gain additional revenue, but it is far more convenient, quality will be higher generally, and we'll recoup the important aviation fuel taxes that are now squandered with highway fuel taxes when you buy at the local gas station.

Posted by: Kent Misegades | August 10, 2011 9:06 AM    Report this comment

John - 109+ airports happily sell autogas and have for many years. Those I have spoken with report approximately the same net margins for autogas as for avgas, although on average autogas sells for $1 less than avgas, according to the latest AirNav statistics. That's terrific news for GA where prices for anything rarely drop.

I am not aware of more accidents related to autogas than you will find for avgas and Jet-A, and this goes for those who buy autogas at the local gas station.

Insurance is not an issue, it costs little and is readily available.

Autogas is not a "magic bullet" and I know of no autogas supporter who has ever made the claim. It is one piece of the puzzle, one that has been an FAA-approved aviation fuel since 1982 that has enjoyed an excellent track record.

Gasoline standards around the US have been tightened since autogas was first approved in 1982, one of the reasons that it has enjoyed this great track record.

Many pilots have been leaving aviation in the past years, and often cite the rising cost of fuel or the maintenance headaches with lead deposits as the reason. Autogas gives one reason for hope that we will not lose even more.

Posted by: Kent Misegades | August 10, 2011 9:17 AM    Report this comment

"I am not aware of more accidents related to autogas than you will find for avgas and Jet-A, and this goes for those who buy autogas at the local gas station."

Love the way you spin that one so that you don't have to stand behind your claim. Just a quick check of the NTSB database proves that mogas contributes to a lot of accidents, many fatal.

Furthermore, when you consider that Mogas is a tiny fraction of the fuel burned in aviation, the proportional record is even more dubious.

For the guy that flys around the patch 20 hours per year by himself with no passengers......have fun with your pump gas. But for the cross country guy and the general public you MUST have clean, dry aviation specific fuel that can be stood behind, when the trial attorney says "Did you know?"

Posted by: DAVID COLEMAN | August 10, 2011 12:43 PM    Report this comment

"Just a quick check of the NTSB database proves that mogas contributes to a lot of accidents, many fatal."

I ran a check. Only one I found was directly related to fuel quality. All the rest with MoGas are the usual suspects (VFR into IMC, fuel starvation, bad maintenance, bad pilotage, etc).

Posted by: Mark Fraser | August 10, 2011 2:03 PM    Report this comment

Use the term "automotive fuel" you will come up with 274 hits. Of those 274 hits there are dozens of reports where automtoive fuel was a factor in the accident. Sure, some of them say "loss of engine power for undetermined reason". Feel free to read the actual report - vapor lock anyone?

But others say "the unauthorized use of automobile gasoline which led to the loss of engine power due to fuel vapor generation" or how about "The pilot's refueling of the airplane with automotive grade fuel which resulted in engine failure due to detonation". Hmmmm......those are pretty clear to me.

So if the total Avgas market is 210 Million Gallons per year, and the total autofuel market for aviation is 10 million gallons a year, imagine what the accident rate would be if all of a sudden we were all using oump gas?

I realize that you folks are trying spread your gospel. I even believe a couple of you folks have an economic interest in pushing your agenda. But the facts are facts. The industry cannot survive without a segregated and controlled aviation specific fuel.

Posted by: DAVID COLEMAN | August 10, 2011 4:16 PM    Report this comment

John, were any of the fuel issues in the search you did related to Rotax engines? Thanks.

Posted by: Jay Manor | August 10, 2011 7:12 PM    Report this comment

"ethanol was never fine in cars" It still isn't, or motorcycles either. Despite living in an area of NC which has relatively little ethanol, my '03 Tacoma (which should be OK with it) still vapor locks on hot days. While on a week-long trip to Colorado last year, we encountered a lot more of it, which resulted in my having to replace the $100+ fuel petcock on my '01 Suzuki dual sport bike.

Posted by: John Worsley | August 10, 2011 7:21 PM    Report this comment

John, what is the relevance of this statement to this discussion:

But others say "the unauthorized use of automobile gasoline which led to the loss of engine power due to fuel vapor generation" or how about "The pilot's refueling of the airplane with automotive grade fuel which resulted in engine failure due to detonation".

I a pilot puts Jet-A or diesel in an engine that should be running 100LL, he'll also have problems. STCs and TCs that cover autogas are not by accident, but the result of the same stringent testing required by the FAA for other aviation fuels. If you don't follow the fuel requirements in these STCs and TCs, you may have problems. I do not see how the existence of autogas as a fuel for many airplanes can be held responsible for misfueling in airplanes that should not be using it.

Posted by: Kent Misegades | August 10, 2011 7:45 PM    Report this comment

kent,

I really dont understand the need for your crusade when nearly every gas station in the country sells you what you want. 100LL is truly a remarkable fuel and its disapppearance will be harmful to high performance piston engine operators.

Posted by: Brad Vaught | August 10, 2011 8:04 PM    Report this comment

Brad, not a crusade, just an effort to correct the widespread misinformation on autogas. I agree 100% that 100LL is a great fuel and do not want to see its disappearance. No one, to my knowledge, is claiming that autogas today solves everyones needs. But it does represent one of the few means to significantly reduce the cost of flying and demonstrate that GA is sincere about reducing lead emissions. Sadly, with ethanol now adulterating much of our autogas supply at gas stations, it is not available as it once was. It is available however at many terminals that could supply airports directly.

Posted by: Kent Misegades | August 11, 2011 6:22 AM    Report this comment

What exactly is the environmental impact of lead in avgas. Have studies demonstrated that GA is actually polluting the environment and by what amount? Everything we do has some negative environmental impact, so maybe we should just quit living. Of course the EPA would outlaw that also.

Posted by: George Dyer | August 11, 2011 9:46 AM    Report this comment

Leaded gas, is just horrible, and, in reality, it's killed more aviators and panicked them into "freezing" at the controls, when things didn't go as planned. There's no statistics on it! Is the government sending you a safety report, that Fannie Mae, and Fannie Mac, derivatives, and stupid congressman and senators have crashed the economy? Of course not!

Neither are they going to point out, that fouled spark plugs panicked an aviator when he tried a go-around, and failed miserably, and fatally, flipping his plane upside-down! Lead salts (bromides) on your spark plugs, are why you must clean the plugs every 100 hours, just to get the engine to run smoothly!

In addition to that, the lead salts surround the radius weld of the exhaust valve, with an enamel-like substance, that looks innocent enough, but actually corrodes the weld, and then the mushroom head falls off the hollow valve stem, peening the piston crown into oblivion, unless the mushroom head drops out the exhaust port, thankfully, on the bottom side of the Lycoming cylinder." Valve shucking", that's why you need to overhaul that Lycoming at 2000 hours!

What about the crankcase and crankshaft? Leaded gas fills them with lead (elemental metal Pb) sludge. That's why your Lycoming crank has "sludge tubes" which attempt to throw out the metal by centrifigal force, so the hollow crank doesn't clog up it's oil passages! Another good reason to overhaul at 2000 hours!

Tetraethyl lead, is a labeled corrosive liquid.

Posted by: Ron Brown | August 11, 2011 8:36 PM    Report this comment

You got some kind of a John Kerry, a politically motivated writer, bad-mouthing the pump gas, you would put in your Bugatti Veyron, or other expensive automobile! I got my own eyes, my own head, my own experience, and I served as a combat soldier in the US Army because I believe in individual rights, and I don't like to see political "authorities" making people squirm about Bugatti Veyron pump gas, just so they can rob your dollar!

Posted by: Ron Brown | August 11, 2011 8:42 PM    Report this comment

Ron, thanks for the comments on the maintenance problems caused by lead in many engines that were never designed for the high levels in 100LL. I lost my well-maintained 1952 C170 to an inflight fire a few years back, luckily without injuries. The NTSB has yet to give a final report on the cause. Looking at the remains of the engine in the pile of ashes that used to be the airplane, one could clearly see a gaping hole where there had once been an exhaust valve. I have often wondered if the problem was lead-related. A year earlier I had to replace a jug due to a stuck valve and the plugs were always a mess due to lead deposits. When I could still get ethanol-free autogas locally, I burned that and never saw such problems. But then BP merged with Amoco and my once-reliable autogas supplier started selling ethanol-blends, with no notice to their unwitting customer, of course. I have also heard that BP removed additional filtering equipment from Amoco's facilities, which used to have a reputation as the seller of the highest quality "whits gas". No more.

Posted by: Kent Misegades | August 12, 2011 6:37 AM    Report this comment

Kent,

I don't know where Ron is coming from, but I have burned 100LL (which doesn't imply 'high' levels) with out issues in a variety of aircraft for as long as it has existed.

Now. you are expressing anecdotal issues yourself.

Better to work with real data and facts as you normally seem to do.

Just saying...

Posted by: Edd Weninger | August 12, 2011 1:34 PM    Report this comment

Edd, I did much of my own maintenance. The mess caused by 100LL on my C145 engine was real, ask any owner of a C170 with the engine. My two sons are aircraft mechanics, they see hundreds of aircraft with the same problem. It is very common on low compression engines, but of course not an issue for those engines that need 100LL. Phil Lockwood presented some convincing arguments too in his talks at Oshkosh this year, reasons to avoid 100LL in the Rotax, based on years of experience, not anecdotes. 100LL is perfect for many engines, but a real headache and potential safety risk for others.

Posted by: Kent Misegades | August 12, 2011 1:40 PM    Report this comment

You don't see the lead issues from outside the engine, you have to see inside the combustion chambers, meaning disassembling the engine, holding the exhaust valves in your hand, witnessing the sludge in the oil, etc.

Flying while the engine swallows a valve, helps too, because then you begin to investigate the cause, after you have landed safely! Yes, I've done that!

Even old school automotive experience helps, back when we had tetraethyl lead in our '60's car and truck engines. Nothing like scratching your head as to why your pick-up's oil pan weighs so heavily for a stamped steel pan, until you discover the weight of the mucky lead sludge, that accumulated there!

Our cars had solid valve stems, so I never had a shucked mushroom head, with them. The Lycomings use a good WWII trick, liquid sodium filled stems, to distribute heat to the valve guide. The radius weld easily breaks, rather than distorts, as on a car.

Oh, by the way, I come from the truth-detector old school!

For decades Lycoming sold their engines to aviation's Tinker Bells under false pretenses. They did it, to extract thousands more dollars from the well-heeled. They sold new engines, and tiered the prices as new, factory rebuild, and overhauled. They were all new, and if you didn't pay the premium price, they downgraded your logbook hours, and used a high-time data-plate from a chopped-up engine, and kept the chopped-up engine's hour's on the new engine they sold as overhauled!

Posted by: Ron Brown | August 12, 2011 2:15 PM    Report this comment

You don't see the lead issues from outside the engine, you have to see inside the combustion chambers, meaning disassembling the engine, holding the exhaust valves in your hand, witnessing the sludge in the oil, etc.

Flying while the engine swallows a valve, helps too, because then you begin to investigate the cause, after you have landed safely! Yes, I've done that!

Even old school automotive experience helps, back when we had tetraethyl lead in our '60's car and truck engines. Nothing like scratching your head as to why your pick-up's oil pan weighs so heavily for a stamped steel pan, until you discover the weight of the mucky lead sludge, that accumulated there!

Our cars had solid valve stems, so I never had a shucked mushroom head, with them. The Lycomings use a good WWII trick, liquid sodium filled stems, to distribute heat to the valve guide. The radius weld easily breaks, rather than distorts, as on a car.

Oh, by the way, I come from the truth-detector old school!

For decades Lycoming sold their engines to aviation's Tinker Bells under false pretenses. They did it, to extract thousands more dollars from the well-heeled. They sold new engines, and tiered the prices as new, factory rebuild, and overhauled. They were all new, and if you didn't pay the premium price, they downgraded your logbook hours, and used a high-time data-plate from a chopped-up engine, and kept the chopped-up engine's hour's on the new engine they sold as overhauled!

Posted by: Ron Brown | August 12, 2011 2:16 PM    Report this comment

I also do much of my maintenance with supervision.

I burned 100LL for 6 years in my C-125 Swift, and 12 years in my O-320 Starduster II. Does the fact that I had no problems relate to the legacy fleet as a whole? I don't think so.

I could go on and state that a lot of legacy planes at LGB, on the same ramp as I, an Ercoupe, multiple 150's and 172s operated by a flight school, older Bonanzas privately operated, etc. might benefit from a less expensive, un-leaded fuel, but they all fly frequently with 100LL as that is all there is.

Ramp chatter sometimes comes to the price of avgas, but I've never heard a pilot say lead has screwed up his engine.

Anyway, this is all anecdotal and worth what was paid for.

Posted by: Edd Weninger | August 12, 2011 2:17 PM    Report this comment

Edd, I'm coming from the old truth-detector school! And, I'm coming from flying 100LL fed engines, that shucked valves in flight, and I witnessed the tear-down of other shucked-valve engines too, that belonged to other people.

Lycoming credibility? No way! They sold new engines for decades under false pretenses, to extract thousands of extra dollars from aviation's well-heeled Tinker Bells! They tiered the prices into new, factory rebuilt, and overhauled. The overhauled fellow got a new engine, but with a data plate from a chopped-up, discarded, engine, keeping the high-time hours from the discarded engine! If you paid the premium price, you got the same new engine, but with "0" hours!

Posted by: Ron Brown | August 12, 2011 2:28 PM    Report this comment

With the 1500 character limit, i can't say everything I want to, here! Anyone who's torn down engines, especially in the 1960's, knows the detrimental effect of lead sludge! The light-weight, steel-stamped oil pan from a pick-up truck, always felt unusually heavy, back then! It was the weight of the muck accumulated in the pan, the elemental Pb lead sludge, that weighed so heavy! In those days, TEL was used far more extensively, up to eight times as much, as modern leaded gas. You can find grayish lead sludge in your airplane's 100LL fed engine's oil filter, even today! The corrosion on your exhaust vales and exhaust component's is always eating away the engine's metal! The spark-plugs are constantly fouled with lead bromides, formed after combustion from chemical "scavengers" in the 100LL, intended to make the lead go out of the combustion chambers via the exhaust.

Nasty stuff! Don't you dare put it in your Bugatti!

Posted by: Ron Brown | August 12, 2011 2:47 PM    Report this comment

Anyway, after flying a severely shaking airplane with a shucked valve, I really DO NOT CARE, if my elastomer swells from pump gas, (although it doesn't really swell any more than in my car or pick-up, or my buddy's Bugatti)

Of course, I am lucky to have an 80 octane engine that doesn't detonate, ping, or knock, so, I can't advocate for everyone, but so many of us can use pump gas!

Posted by: Ron Brown | August 12, 2011 2:56 PM    Report this comment

I find this discussion absolutely fascinating, and I must admit that I am more confused than ever.

For the past few years I’ve been flying Katanas behind Rotax engines, fuelled by gas that my flight school gets from an auto gas fuel distributor, and keeps in its own tanks. My biggest limitation with these aircraft was flying cross-country due to the lack of fuel, let’s call it pump gas, available at my destinations. My flight school would only allow the use of 100LL in its aircraft as a last resort, followed by an accelerated engine inspection.

Recently I bought an old Piper PA-22 108 Colt. It has the venerable Lycoming O 235-C1 in the nose, the same engine I learned to fly behind in the good old days of low octane aviation fuel, in the seventies. I use the 100LL now simply because it is readily available. I can understand why Lycoming is clarifying its position on the use of mogas. There is a potential for a lawsuit somewhere there for sure, but I have a hard time believing that any level of additional regulation would make the auto gas better than it already is, provided it is ethanol free. After all we have “stringent” regulations in place on our financial sectors as well, and yet we are in this current economical mess anyway. I wonder if our blind belief in regulations is giving us a false sense of security about our “beloved” 100LL as we once had in our financial institutions.

Posted by: Edward Dolejsi | August 15, 2011 12:12 PM    Report this comment

Edward - if ever there was justification for a class-action lawsuit, it would be against the EPA and fuel providers for the massive damage that ethanol is doing to millions of engines in the US. Where is a trial lawyer when you need one?

Posted by: Kent Misegades | August 15, 2011 12:18 PM    Report this comment

Kent: A trial lawyer is where the money is.

Textron has so much money, all the lawyers are for Textron, no matter what! They might say they are on some other side, but, they are on Textron's side, trust me, I know!

I understand you want to sue the EPA, but why would a lawyer sue federal handout money? Rather, lawyers want to be in line, for the handout money!

On any issue, modern lawyers on both sides, get together, find the biggest piece of the pie, and divide it up amongst themselves.

In politics, there is a "straw vote", likened to holding up a straw to see which way the wind is blowing. Lawyers look for where the most money is coming from!

Corruption is so rampant in our country, money from George Soros, money from Saudi's, money from New World Order and the Bilderburgers, money from the Tri-Lateral Commission, money from China, usurps the will of the American people, and honestly, the foreign interests are seriously trying to destroy America from the inside, using the communists from the Obama administration.

Posted by: Ron Brown | August 15, 2011 12:46 PM    Report this comment

All of that, includes controlling Big Oil, and monopolizing the wonderful God-given gift of liquid hydrocarbon fuel. Al Gore is an imbecilic thief, epitomizing the "green" movement, for his own, and his cohorts, monetary gain.

The fuel monopoly must be stopped. The communists and socialists, the NWO people , constantly distract the public by condemning God's hydrocarbon fuel, as if it were evil, and by proposing using cropland to grow fuel and starve people, and by proposing "pie-in-the-sky" alternative fuels which make no sense whatsoever.

According to our ever corrupt politicians, you are: 1. Using saw grass to power your car. 2. Using Hydrogen to power your car. 3. Using Lithium Ion batteries, hydrogen fuel cells, the utility company's electricity to power you car.

Of course, none of it is true. They have been lying, for a very long time!

Posted by: Ron Brown | August 15, 2011 1:10 PM    Report this comment

I too share Ed's confusion. Just a thought, which may be a partial solution,might be to convince oil companies to market aviation grade (93 or 94)octane ethanol free mogas to drivers of cars so they get pure gas and we get the savings through increased sales(to car owners). I can see the ads now "We carry aviation grade gasoline" they can charge a premium for it which would still be much lower than 100ll. Any thoughts?

Posted by: Steve M | August 15, 2011 1:13 PM    Report this comment

Regarding gasoline, for Aviation, an Aviator needs to know basic Information. 1. Octane molecule gasoline does not detonate. You can't get Octane molecule gasoline, because no one refines it for Motorists and Aviators, it would be too expensive to refine. 2. Heptane gasoline is available, refined in huge quantities, for Motorists and Aviators. Heptane gas detonates, so additives are necessary to inhibit detonation.

(Detonation is the all-at-once, spontaneous combustion of the entire fuel charge in the combustion chamber, causing high temps which melt the combustion chamber aluminum, and the piston crown aluminum. Aside from being way too hot, the explosive force of a detonated fuel charge is greater than TNT, physically destroying engine parts from sheer force. Gasoline engines depend on the fuel charge burning a slow flame-front, like a grass fire would burn from one edge to the other edge, rather than all-at-once.)

3. Tetraethyl lead, stopping detonation, (via it's opaqueness to infra-red heat), allowed automobiles, farm implements and pumps and generators to work, rather than to detonate, and in WWII, TEL allowed high-power warbirds up to 2800 horsepower per engine to run without detonation. 4. Aircraft engines are designed for an Octane Rated fuel, usually ranging from 80, to 115, the rating reflects a resistance to detonation, accomplished by additives, and then compared and rated to genuine octane molecule fuel.

Posted by: Ron Brown | August 15, 2011 1:49 PM    Report this comment

4. An Aviator should know his engine's octane rating, as designed by engineers. ( GA planes are usually 91, some higher, many lower, at 80) 5. Octane ratings methods vary, so, 87 rated fuel, might be some other number, if rated by a different method.

6. Generally, on low horsepower, low-compression ratio engines, pump gas won't detonate. (With an O-540, 80 octane engine, 7.1 to 1 compression ratio, I feel very safe, with pump gas.)

7. Most four cylinder aviation engines do require 91 octane. However many people used pump gas when stranded in a location without Avgas, then went on using it successfully when no detonation occurred.

8. A detonating engine run so roughly as to shake the plane, it melts the chambers in seconds, and destroys the engine immediately. More common, Partial Detonation doesn't catastrophically destroy the engine immediately, but the piston crowns can melt and solidify again so rapidly as to cause whirlpools to form on the crowns, visible when the engine is torn down. Connies sold to South America in the sixties often detonated over water, and a hole (whirlpool) completey through the crown, would catch the engine on fire!

Posted by: Ron Brown | August 15, 2011 2:18 PM    Report this comment

9. An Aviator, who decides to experiment with pump gas, needs to monitor and inspect the engine for any signs of detonation (inspecting spark plugs) and quit using it , if there is evidence of pre-ignition, knocking or pinging, just as automotive spark plugs are inspected, for pre-ignition. Usually, a properly timed, small airplane engine won't detonate, and won't pre-ignite, making pump gas a viable option. This has been proven for you by the Petersen and EAA autogas STC's.

Posted by: Ron Brown | August 15, 2011 2:27 PM    Report this comment

Syeve - 91+ AKI is plenty for all piston engines that currently support autogas. Petersen autogas STCs for Lycoming's engines specify 91 AKI. Higher octane is a waste of money. Sooner or later, one of the major avgas suppliers is going to start supplying ethanol-free autogas to pilots, boaters, etc. The number of retail stations selling ethanol-free has actually been increasing in the upper Midwest, where a small ethanol-free gas war appears to be evolving. Margins or so tight, gas companies can not afford to be the last to join their peers.

Posted by: Kent Misegades | August 15, 2011 2:54 PM    Report this comment

Ron, you seem knowledgeable about different fuel types and the effects to different engines, but I do not think that this aviation blog is the right forum for vitriolic political discourse i.e. Tinkerbell,George Soros, Al Gore, Obama communists, NWO.etc.I think pilots should be above that kind of hyper-partisanship. (at least here) Glen Beck and Fox news has blogs that are more suited to that type of discourse. Also please define "Tinker Bell"?

Posted by: Steve M | August 15, 2011 3:15 PM    Report this comment

Well, maybe I dip in the wrong pool sometimes!

As for Tinker Bell, just google her, especially images, she's a cute little Disney character!

I'm cool with her, but frankly, I just don't have very much in common with her!

Posted by: Ron Brown | August 15, 2011 3:27 PM    Report this comment

"....Also please define "Tinker Bell"?..."

Please don't...

Posted by: Edd Weninger | August 15, 2011 3:27 PM    Report this comment

Glad you guys got a sense of humor!

Posted by: Ron Brown | August 15, 2011 3:29 PM    Report this comment

LOL

Posted by: Steve M | August 15, 2011 3:49 PM    Report this comment

Had three partial engine failures on my Continental O-300 due to 100LL building lead up on the valves. My mechanic said he wasn't going to work on my cylinders anymore until I stopped using it. I now use a mix of 50/50 100LL and regular auto gas and haven't had a problem since. Don't like having the ethanol in the gas but can't get any without it where I am.

Posted by: Duane Hallman | August 15, 2011 4:29 PM    Report this comment

The thesis by Senior Vice President Mike Kraft on the fuel situation is ideed of great "academic and historical" interest, however, unfortunately of little practical importance. I certainly do not expect that a representative for Lycoming be able to provide a solution to the fuel mess we are in. However, what I do expect is that a Lycoming representative on Mr. Kraft's level be able to provide some needed recommendations to customers with respect to upcoming engine major refurbishment. For example;what are the Lycoming recommendations for a pilot with an engine approaching end of TBO? Should he "do nothing" and try to "stretch" the engine life till the fuel situation is resolved? Is there something this pilot can do to "facilitate this stretch" and which does not present a hazard or which is not an "economic waste" with respect to full overhaul when the fuel issue has been resolved? What is a pilot's "max.Economic Exposure" if a regular overhaul is done now assuming the for Lycoming "least favorable fuel" being the choice? These are example of customer service related issues which I feel Lycoming should be able to address at this time and which will be of great help to Lycoming customers. We are all very concerned about the increasing cost of flying and this is one area where costs are significant and where resources can be unnecessary wasted.

Posted by: HELGE SKREPPEN | August 15, 2011 6:40 PM    Report this comment

Oh the ecstasy! Oh the agony! SI 1070Q finally lists my engine as eligible for mogas (O-360F1A6) but 1) there's no STC for it from anyone and 2) It's not available in So. Calif.

AAAAAAAAAGGGGGHHHHH!!!!!!!!

Posted by: David Rosing | August 17, 2011 10:02 AM    Report this comment

Reading all of this I conclude that it is a safe bet for the engine makers to approve mogas for some of their engines, since an STC is needed for the actual aircraft model to use it. Last time I checked, this is an involved and expensive process. Individuals will likely not invest the money to do it, and the aircraft manufacturers are probably not interested in doing it either. There is no money there for them to be made. In fact, as I am reading these posts, it is likely that many of the pump gas users , if they fly certified aircraft, may be flying illegally.

Posted by: Edward Dolejsi | August 17, 2011 10:26 AM    Report this comment

The surest and quickest way to turn oil black is to have poor dynamic ring seal. Detonation (from whatever reason) will force combustion gases past the rings, before gas pressure can get behind the ring to push them out against the cylinder wall. That will blow the oil off of the ring face and cause even more heat... causing more detonation and maybe pre-ignition.

Detonation can be pretty subtle (or not). And it's generally, logically, affected by heat. Sometimes poor combustion chamber design clearances will surprisingly cause detonation, even at low temps.

If it's close to pre-ignition with an overheated spark plug, you'll see a very slight, fine, small "peppering" on the center insulator and at the very "pre-onset" of pre-ignition cause by an overheated spark plug, the center insulator will take on a very slight "green" tint (as if you can "imagine" green, it is green). The PA-32 that I fly treated us with 4 very subtly "green" insulators on the 2 rear cylinders - so - "Lean of Peak" was not an option....

I keep hearing people saying that dark oil is "lead" and that lead causes "sludge" - but what I've mostly seen is accumulated carbon deposits that happens to include the fuel's lead.

Lead fouling plugs - I think that lead bromides are supposed to take care of that. Something like 1500f is required. If the spark plug insulator never gets to 1500f, lead will accumulate. Same with the exhaust valve, I'd guess.

Posted by: MARC SALVISBERG | August 17, 2011 1:28 PM    Report this comment

Marc: TEL is a liquid corrosive chemical that's added to the gas. After combustion, chemical reaction results in Pb elemental solid metal forming, from the TEL molecules, which is where the heavy metal sludge comes from. Most of the Pb goes out the exhaust, eroding slightly the exhaust parts, via a sandblasting effect.

Commonly, people are confused about soot and carbon, thinking that it is lead, but, the lead being talked about is TEL, tetra ethyl lead, and the after-combustion Pb atomic chart lead that is a gray metal.

The lead scavengers added to the gas, are to combine with the Pb, escorting it out the exhaust, to prevent sandblasting and sticking damage to the parts.

1500 degrees is okay, if located in the center of the fuel charge gases, but engines can last so much longer if the metals used in their construction never exceed 300 degrees!

Posted by: Ron Brown | August 17, 2011 1:51 PM    Report this comment

"Lycoming firmly believes that an equivalent performance unleaded aviation grade replacement for 100LL is the best total solution for our industry overall."

This is where the entire problem lies. This is incorrect. The greatest benefit for the future of piston aviation is to go to a Diesel cycle engine. This will allow the future combustion of low manufacture cost high energy density bio fuels in the future and lower cost higher energy density diesel or Jet A fuel right now. Not only will this help the current GA population in the US and Western World, but also GA in the large sectors of the world where high standard gasoline just isn't available.

I think the continued pursuit of gasoline alternatives for engines and applications not suitable to mogas is very short sighted.

Posted by: Henning Heinemann | August 21, 2011 8:27 AM    Report this comment

I AM FLYING NAVAJO PA31-310 WITH TIO540 ENGINES IN INDIA.I AM UNABLE TO BUY 100LL.CAN I MIX MTBE IN AUTO GAS OF 91 OCTANE TO INCREASE OCTANE RATING TO 100.WHAT COULD BE THE PROBLEMS?I WILL ADD LIKE 30% MTBE AND GET THE FUEL TESTED FOR OCTANE RATING.CAN ANY ONE COMMENT ON THIS?LIABILITY IN INDIA IS NO PROBLEM.i JUST WANT TO KNOW IF IT WILL WORK WITHOUT KNOCKING.

Posted by: sam verma | December 30, 2012 3:08 AM    Report this comment

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