San Carlos — try mogas

As reported this week by Flying, the EPA has issued its findings on lead emissions it has been monitoring the past two years at 17 airports across the country. For pilots in Southern California and the Bay area, the news was not good:  “The EPA’s findings from airports where the testing was carried out indicate that airports in California — McClellan-Palomar Airport in San Diego County and San Carlos Airport in San Mateo County — exceeded lead air quality standards. A third airport in California, Palo Alto Airport, was only slightly below the legal threshold for airborne lead emissions.”

Managers of these airports are now under even more pressure than in the past to deal with this public relations dilemma. The Silicon Valley’s Mercury News was quick to ask San Carlos airport manager Gretchen Kelly for comment on the EPA’s findings: “We have monitors on the airport that are measuring zero … and that’s where people are.”  The article continues: “Kelly said she will gladly sell unleaded fuel the minute it’s approved by the FAA.”

Perhaps one of our readers based at San Carlos can inform Kelly that the FAA first approved lead-free mogas as an aviation fuel 31 years ago.

Last year your bloggers commissioned a study of the FAA’s aircraft registry that showed that more than 80% of all piston engine aircraft can operate  safely and legally on mogas. We also estimate that these 80% would consume approximately half of all the fuel sold for piston engine aircraft since that is what has been documented to be the case in Europe, where mogas is widely available at airports. For the remaining 20% that currently require avgas, the new INPULSE water injection system allows essentially any of these aircraft to operate on premium mogas.  FAA approved STCs already exist for many models of the Baron, C210 and C188 aircraft with others possible upon demand.

With the recent announcement of Airworthy Autogas, based in Phoenix, Arizona, there is now a serious supplier of aviation-grade mogas in the U.S.  Airports selling mogas now can be found on this list and map from your blogger, Dean Billing.

The news from the EPA does not have to mean the end of flying for piston-engine aircraft at the affected airports.  It might just provide the needed motivation for the expanded use of mogas into the western states, not only reducing lead emissions, but also lowering the cost of flying.

With lower costs will come more flying activity and potential increase in overall revenues to the many aviation-related businesses that are suffering due to lack of flying activity.

Let’s hope that this will be the silver lining to the dark clouds created by the EPA’s findings.


  1. says

    The EPA and the various Bay Area government agencies involved were advised against positioning these monitors directly behind aircraft in the run-up area at the San Carlos Airport. They ignored the warnings.

    At best the monitor results are suspect if not completely skewed. Imagine positioning these monitors behind your car in your driveway or garage versus positioning them within your neighborhood. Which do you think would be higher?

    This study is self-serving and only proves that these over zealous government agencies are unconcerned with the facts based upon science, but instead are more concerned about appearing as if they are doing something.

  2. Tom says

    The FAA can approve fuel all it wants, but doesn’t it require that the airframe manufacturer officially approve it by type certificate before all of those aircraft can use it? Otherwise very one has to buy STCs and possibly install expensive modifications. Lycoming has already listed many engines as capable of using 93 octane, including my Cardinal’s O-360. Cessna has not. Am I misinformed?

    • Greg W says

      The FAA allows “the next higher grade” of avgas to be used, as determined by the type certificate. For instance the C-177 was certified with 80/87 avgas, the 177B ser. no. **** with 91/96. This is how we are allowed to use 100LL when very few aircraft were originally certified with it. The key is that it must be an “approved” avgas, today’s standard is ASTM D-910. Autogas is a different ASTM spec. and so NOT “avgas”, hence the need for a supplemental type certificate,it is a different fuel . The problem is not truly the FAA but the fuel producers and distributors,we need approved fuel and so will use whatever they produce, they have no incentive to produce a different gasoline.

      • Kent Misegades says

        Mogas is an FAA-approved fuel, provided it meets ASTM D-4814 (all vehicle fuel in the U.S. does), has the correct AKI rating, and contains no ethanol, unless the STC or TC allows it. Nearly all new aircraft engines these days are designed for mogas and it appears on the type certificate. In looking for the mythical drop-in replacement, we are attempting to support yet another boutique fuel whose demand will only continue to drop. Who would want to invest in that? Far wiser would be to adapt our aircraft to the huge volume production of gasoline, aka mogas. For this reason aircraft diesel engines are gaining in popularity, due to the large production of Jet-A and its availability everywhere.

  3. Snarge says

    Hmmm. A survey did go out to folks based at the airport regarding interest for unleaded fuel. Reportedly, very low interest. Besides, most of the fuel that is burned by piston aircraft are from aircraft that CANNOT use mogas. Look at the statistics yourself. Article = bogus and misleading. Shame, since this is supposed to be an aviation friendly source of information. Quotes are copied from another source. Makes it look like mogas was never looked at. I spy foul.

    • Kent Misegades says

      “Besides, most of the fuel that is burned by piston aircraft are from aircraft that CANNOT use mogas.”

      This is one of those urban legends that has no factual basis. We recently forced an FAA official to admit that the 70/30 split of avgas/mogas sales is based on anecdotes from a decade ago. Our study of the current FAA aircraft registry, by contrast, proves that well over 80% of all piston engine aircraft can safely and legally operate on mogas today, nearly all with no modification. Of course pilots at this airport would prefer someone just solve the leaded avgas dilemma, at no cost and no disruption. Even a low-cost mogas STC takes a bit of effort to get, and many aircraft owners won’t even do this. We are our own worst enemy in aviation.

  4. Rich says

    I could be wrong but I have never heard any knowledgable engine builder or manufacturer say that lead was put in fuel to lubricate anything.
    The lead was put in fuel to boost octane, make it burn slower rather than explode.
    Prevents “ping”.
    Where do peple get the idea it is supposed to lubricate valves or anything else?
    I am open to other factual explanations.

    • Greg W says

      The tetraethyl lead was indeed added to enhance the octane rating of the fuel. The “lubrication” benefits were a case of using a compound that was already there to added advantage. The lead deposits allowed less durable, less expensive materials to be used as the lead became a sacrificial coating that was continually replaced during normal operation ( this was/is the cause of “valve recession” when running unleaded gas in a “leaded” engine. The normal case is that there is no benefit to the leaded fuel other than the ant-knock properties. Most grade 80 avgas was no lead, it was added on a as needed basis with each batch of fuel to meet octane requirements. The 100VLL made quite the stir when revealed that the 100LL being produced was a much lower lead content than thought by most, the VLL simply codified what was already being produced and sold. The earlier astm specs. for D910 avgas do not state a minimum amount of lead only the maximum, only the amount needed to meet octane rating was added. The newest revisions of ASTM D910 does however list a minimum required lead content.

  5. Joseph N Greulich says

    I thought I would add my thoughts, while I think it would nice to get the lead out and should be , there has been some improper testing procedure done by the EPA. As I understand it they placed the monitoring sniffer behind the engine run-up areas. The person who discovered this calculated that at the collected lead concentration level it would need to come from millions of gallons of 100 LL , they are at it again !

    • Kent Misegades says

      This screw-up would surprise no one. But the reality is, we lost the argument in favor of leaded avgas in the public eye decades ago. People are terrified of it today, and we’re the last people on the planet using it. We all fly around with a huge bull’s eye on our aircraft, especially in California. We are not going to win this battle, so we had better start preparing for the end of avgas ASAP.

  6. says

    The thing with Airworthy Autogas, is they can expand their market beyond Aircraft and thus reduce the cost. Ask boaters the number one thing they spend money on is gummed up fuel systems. If there is a lead free 90-100 octane fuel that is stable for extended periods of time with a low vapor pressure then it would cut maintenance on boats by a marked percentage. I know vintage car owners that go to the marina to get their ethanol free fuel here in my area (though more stations now have ethanol free fuel). They could also market it to lawn services that use their equipment enough that the damage done by cheep auto gas is noticed. If FBO’s could position the pumps so they could sell to boaters, vintage cars, etc they could increase their sales. However, I think we will see more and more compression ignition engines running Jet-A in the future especially for the big piston aircraft due to economies outside the US. This is something to consider if you are at TBO IMHO and there is a STC for a compression ignition engine for your plane.

    The one hiccup will be engines designed for lead need it to prevent lifter wear, for those engines you may be in for a lot of money when 100LL is no more.

  7. Jeff says

    Why only 17 airports and why only Calif. airports exceeded the limits?
    As Ca. shakes the tail so goes the dog, the rest of the country will follow. Remember MBTE, who required it first?
    Is Airworthy Autogas available nationwide? Or available at all yet?
    What is the cost to an airport to install another tank, pump, etc?
    While I would love to see lead free fuel, and am a proponent of mogas I am also very skeptical of anything environmental coming from Ca.
    I bought a piece of decorative wood the other day on the east coast and on the packaging it said this product has been shown to cause cancer in Ca.

  8. John Drago says

    I would be suspect of the EPA and the Government in general when it comes to the reportng of “their” monitors, where they place them and the results. How come some monitors report zero, and thats where the people are, at the San Carlos Airport? I am remended of the monitors the government set up to prove global warming a few years ago. Remembering they set some of their monitors in blacktop parking lots to help draw up the ground heat to enhance their PROOF that global warming exists.

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