New study shows autogas can power 80% of piston aircraft

The Aviation Fuel Club has released initial results from a study that shows between 80% and 83% of the current fleet of piston engine aircraft could safely operate on autogas.

First approved by the FAA as an aviation fuel in 1982, autogas (also known as mogas) is ethanol-free, lead-free automotive fuel. Either 87 or 91 AKI may be used, depending on the engine’s STC or TC. About 59,000 autogas STCs have been sold since the FAA approved the first one in 1982, club officials report. Autogas currently sells on average for about $1.40 a gallon less than leaded avgas at airports where it is offered.

Todd L. Petersen, a founding director of the Aviation Fuel Club and owner of many autogas STCs, described the motivation behind this study: “We looked at the FAA’s registry of aircraft last in 1992, two decades ago. We determined then that approximately 115,000 aircraft were capable of burning autogas using STCs from the EAA and my company, Petersen Aviation. This represented about 78% of all piston aircraft in 1992, and we did not include homebuilts, ultralights or piston rotorcraft, most of which may operate on autogas. Much has changed since 1992, with many owners of heavy twin aircraft that needed avgas having switched to turbine aircraft, and with continued growth in the homebuilt and more recently the LSA sectors. We felt it was time to look at the latest data and see to what extent autogas could be used to lower the cost of flying and reduce lead emissions from our aircraft.”

To make sense out of the FAA’s massive online registry of aircraft, the club employed the services of Dilip Jumani, a database expert and member of EAA Chapter 1114 of Apex, N.C.

“We asked Dilip to extract from the registry the number of all active aircraft that are currently covered under the autogas STCs from the EAA or Petersen Aviation, being careful not to double count,” explained club director Kent Misegades. “We were not interested in the number of aircraft which actually have the STC, only the number which could legally operate on the fuel today. Unfortunately, there are many textual errors in the registry, requiring Dilip untold hours of tedious work to assure accuracy in his work.”

The study revealed that 127,168 fixed-wing and rotary piston aircraft can operate with autogas today under the EAA or Petersen STCs. This represents 80% of the 159,007 active aircraft in the latest General Aviation Statistical Database from the General Aviation Manufacturers Association (GAMA).

Autogas-burning aircraft are found in every class — from light aircraft (Piper J-3), popular two-and four-seat single-engine pistons (Cessna 152/172/182, Piper Cherokee), some high-performance singles (early Bonanzas), crop dusters (Ayres Thrush, Grumman Ag Cat, Piper Pawnee), and radial-engine aircraft including many models of the Stearman, T-6, DeHavilland Beaver, Beech 18, and even the mighty DC-3. This also includes piston-engine helicopters, 74% of which may operate today on autogas.

Two other categories of aircraft were considered in this study: Experimental- Amateur Built (E-AB or homebuilts) and Light Sport Aircraft (LSA). In its 2012 Report to Homebuilders, the EAA claims that 33,000 E-ABs are registered and a net of 500 are added annually. By definition, 100% of these homebuilt aircraft may use autogas (or any other fuel), although some have high-performance powerplants that will require the use of 100LL avgas, Misegades noted.

According to the most recent listing of the LSA market by LSA expert and Light Aircraft Manufacturers Association (LAMA) Chairman Dan Johnson, there are 2,235 S-LSA aircraft currently registered. Approximately 1,600 of these use engines (Rotax, Jabiru, VW conversions, etc.) that are factory-certified to operate with autogas. The remainder of the LSAs use Continental’s O-200-D engine, which is not currently certified for autogas. With Continental now offering its autogas-burning O-200-AF, we expect these LSA manufacturers to offer this engine in the future, Misegades noted.

Including E-ABs and LSA aircraft to those covered under STCs brings the total to 83% of all piston engine aircraft that could be operated today on autogas. Not counted here are several thousand ultralight aircraft, typically powered by two-stroke engines or the same powerplants found in modern LSAs (Rotax, Jabiru, etc.) that are generally run best on autogas.

The bottom line: Somewhere between 80% to 83% of all active piston engine airplanes and helicopters registered in the U.S. could operate on autogas today, dramatically reducing the cost of flying and lead emissions from general aviation, according to the report.

The authors of the study are now analyzing the data to determine these percentages in several different categories of aircraft (light single, high-performance singles, twins, etc.) and to estimate the relative fuel consumed. Details will be presented during a forum “Autogas at 30 Years” on Thursday, July 26 at EAA AirVenture Oshkosh. Speaking at this forum will be a number of experts on aviation fuel. Topics addressed will include a recent development allowing the remaining 20% of high-performance aircraft to use autogas.

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  1. Ernani Seddon says

    I live in Brazil and I know a person that flew his Piper Arrow for 23 years taking of in avgas and switching to 100% ethanol To land he went back to avgas.
    Once in a while he would switch the tanks and invert the fuel. The tank that had ethanol h replaced with avgas. He flew for 23 years and no problems whatsoever.
    There are several Piper Pawnees and Cessnas Ag Wagon flying on 100% ethanol. There were some carburetor adjustments and a small tank where they placed avgas with a small pump cold start the aircraft.
    I saw a Cessna 195 with 400 HP Radial flying with Mogas and 25% alcohol and no problem reported.
    I wonder how much miss information is generated by the avgas manufacturer.
    If anyone has been flying a Cessna 170 and a Citabria with mogas and alcohol please let me know

  2. Andrew says

    I’ve heard many times, including here, that all US gas must contain some amount of ethanol/alcohol, but all except for one gas station in my small Oklahoma town advertises that they sell 100% gasoline. Is someone lying, or is there a way around having to include ethanol?

  3. bbs53 says

    This debate has been going on for oh 30 years or so. If it were as simple as the ignorant Europeans think, it would already be done but you cant just put 20% or 60,000 planes on the tarmac. Most of these planes never leave the US, so it is a US problem and not anyone else’s. This is a simplistic study no matter how hard he tried to make it relevant, just because an engine will operate on a different fuel does not make it the ideal fuel and lead was added not only to boost octane ratings but to lubricate the valve train, sucking a stuck valve somewhere over water may not be a good reason to change over just because the engine will “run” on another fuel. In 1986 when they removed tetra ethyl lead from auto fuel, it caused a lot of problems with everything from hoses to internal damage. It was made even worse by the unnecessary addition of alcohol to the fuel, a total contaminant as far as aircraft are concerned and everyone else except the corn farmers and Archer Daniels. Yes, we were and still are being duped by corporate robbers and wacko enviro idiots. Now that alcohol is in the fuel supply, it will nearly be impossible to remove. Now you have another one off fuel for aircraft and that is exactly where we are right now. The answer is of course to make the engines run on out of the pump auto fuel or jet-a. The best answer would be to remove corn from our fuel and use it for something more efficient. However we have an idiot at the head of a monster that responds very slowly if at all, I sure wish that all airplane owners would have had the sense to vote for what was best for GA, and the moron in that position now is NOT that person. At least Mitt owns a plane! This will not go away any time soon, but 2020 is coming.

  4. says

    All USA “autogas” is required to have 10% alcohol in it. The gasoline in the pipe is alcohol free, but it is not autogas. We need to get rid of the Bush era 10% alcohol corn subsidy then we can do the autogas again. I wonder how many folks realize the gas mileage hit they are taking by using that alcohol contaminated fuel…

  5. JJherrign23418 says

    tax the sh!t out of leaded fuel and get it out of our environment and my kids.  Either use auto fuel or switch to Jet-A / diesel.  Quit being 19th century and stupid!

  6. Erosiak says

    While those statistics are important, this article misses just how much of 100LL aviation fuel the remaining 20% consumes. And, that the remaining aircraft requiring 100LL consume the majority of the aviation fuel sold. We need a 100% solution.

    • Kent Misegades says

      In Germany we know that about 50% of all fuel sold for piston aircraft is mogas.  No accurate study has been done in the U.S., so we can only assume that the split would be 50/50 mogas / avgas if more mogas were available at airports as it is in Germany.  If anyone can determine what is sold in the U.S., we’d like to know.  Fact is, some 80% of all piston aircraft can run today on mogas, and these surely are burning a large percentage of the total fuel.  With more large piston aircraft being retired and owners moving to turbines, and with the latest generation of aircraft engines being designed to operate on mogas, this trend can only accelerate. All the experts and even the UAT-ARC now admit that a 100% solution is unrealistic. That’s why Lycoming, Continental and most others are now certifying engines to operate on mogas.

  7. Bill Leavens says

    IF (if) you can find auto fuel without ethanol.  And ethanol seems to be one of the biggest hoaxes ever perpetrated on the American public.

    • Kent Misegades says

       Not entirely true.  Just because ethanol-free is not available at a gas station does not mean it is not at the local fuel terminal.  Ethanol may not be pumped in pipelines, so ethanol is added to it at the terminals.  Airports should obtain their mogas at these terminals.  110 of them already do.

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