The biggest topic of discussion in general aviation these days is the effort to develop a 100-octane unleaded fuel that can be a drop-in replacement for 100LL.
It seems that everyone has an opinion about a solution, but there seems to be problems with every solution — problems that people try to overlook.
Over the holidays I was cruising the internet and came across a discussion on the unleaded avgas subject. One of the comments stated that since the EPA has established that leaded avgas represents a significant health hazard, it needs to be banned immediately. I was going to respond and point out the error of this statement, but in the holiday spirit I passed and had another eggnog.
The problem with the statement is that the EPA study did not in any way, shape, or form prove that leaded avgas is any kind of a health hazard. In fact, it did just the opposite.
It showed that a group of people trying to prove that leaded fuels are a health concern are wrong. I believe their data analysis concluded that there was no significant difference in blood lead levels between people living by an airport and the general population.
This is the same conclusion from a very large sampling in the late 1960s that compared the blood lead levels of taxi drivers in New York City to that of natives in Africa who had never seen an internal combustion engine run on leaded fuel. Even though the taxi drivers were around exhaust from cars burning leaded fuels every day, there was no significant difference to that of the natives who never came in contact with an engine burning leaded fuel.
So instead of reporting the results that the EPA found, they added a weasel word to their report to make it look like their tests supported their pre-drawn conclusions.
They reported that leaded avgas PROBABLY represented some kind of health hazard.
PROBABLY? If I had ever added this to the conclusion of a test program while working at Shell, I PROBABLY would have had a much shorter career there.
In the news they are always saying that we need to follow the facts and use good science.
Using those guidelines, I offer the following options on what path to follow:
Option 1
Scrap the whole 100 octane unleaded project for now and keep 100LL for the foreseeable future.
This will save about a dollar a gallon in fuel costs, protect everyone’s exhaust seats, and ensure a continued supply of safe fuels all across the county.
It will also give time to allow the unleaded fuel suppliers to solve their technical problems and maybe develop an unleaded fuel that can be used in the entire GA fleet with little or no significant technical problems.
Option 2
Do a gradual reduction in the lead level allowed.
Today a gallon of 100LL typically contains around 2.1 grams of tetraethyl lead (TEL).
Say we reduce that to 1 gram per gallon by 2035 and 0.5 grams by 2045.
This will allow the industry to gradually improve their fuels and the engine and engine component business to upgrade their products to work with the new fuels.
It will also allow those people who believe that one must follow the facts and the science only when it agrees with their pre-drawn conclusions to claim that they reduced the lead level in the atmosphere.
Option 3
Follow the current push to replace 100LL with 100UL by a specific date, like 2030 chosen by the Eliminate Aviation Gas Lead Emissions (EAGLE) initiative, a government-industry collaboration to make general aviation lead free.
This is the most expensive option with a lot of possible problems, such as exhaust valve recession, runoff water pollution, seal compatibility, spark plug fouling, and many more.
And it is not based on factual data or science.
Everyone has heard that lead is bad, but it has to be in a form that people can ingest. Lead is all around us in items such as car batteries, fishing lures, many shot gun shells, wheel weights for tires, and a lot of other industrial uses.
Hopefully we can get back to using factual data and good science to make decisions, not just opinions. But probably not.
Lets get rid of avgass and old petrol engines from 1930’s, and get new, more efficient, lighter engines powered by regular autogas.
By ‘get rid’ of the 1930’s engines, do you mean replacing the approximately 250,000 piston engines in the US fleet. ..at what cost ? Then, replace them with what engines…that don’t exist, other than the very successful Rotax 900 series. But they top out at 160 HP, and are in few certified aircraft.
Certifying a new engine takes years, if not decades. DeltaHawk is a recently certified Diesel, and it being evaluated in a few airframes.
Unlike autos, that get replaced in 10-15 years, GA aircraft average 50 years old, with a number from the 1920’s and 1930’s still flying.
My 1961 Cessna has an STC for Mogas, but it is not available withing 500 miles of my California location. So, it’s 100LL in the tanks.
Mr. Visser seems to have a very firm grasp of the Kehoe Principle.
I remember back to large radials days they used 115/145 fuel. Has there ever been any research accomplished on crews, maintenance people, and areas like the flight line, runways etc? Ya, I’m a old fellow and I don’t recall anyone dieing from those days??
Environmental and health issues aside (and they are real and supported by the science), and also ignoring things like plug fouling, etc, the biggest “elephant in the room” in my opinion is that the world’s supply of TEL is produced by one boutique refinery in the UK (AFAIK). Should they decide (or are forced) to quit production, that’s it…it will mean an immediate crisis in the avgas industry. It would be a start to get the old 80 octane back available for the many aircraft that can use it, and get the 100LL replacement designed/fielded as soon as practicable.
The University of North Dakota tried burning it in their flight school. The unleaded fuel burnt up their engines and they completely gave up on it. I think they know how to really take care of their engines. How’s that for giving it a shot?
If it burns up their engines, it’s going to burn up our engines.
You need to do a deep dive into why UND had engine issues. Other flight schools used it as well and didn’t have problems. UND had warranties for their engines, so operated them as lean as possible without regard to engine life. Surprise, they had valve issues.
Ben is absolutely correct. The all or nothing approach to eliminating lead isn’t working and has made essentially no progress in the 50 years since lead was taken out of car gas. Instead, let’s do something that makes sense by taking an approach of incrementally reducing lead. The old 80/87 fuel had 1/4 the amount of lead present in today’s 100LL, which was the last “drop in” replacement. While 100LL was OK for many engines, many of the older lower compression engines have experienced chronic sticky valves and accelerated valve guide and valve stem wear. A “drop in” replacement means it works for many, but not all.
What is sel and gasoline mix.
Diesel to lubricate and gasoline to help combust.
I own a 2.7 GMC truck with turbo that puts out 310 HP. If they can do it, so can the General aviation Companies do it!
The answer is not to keep spewing lead into the atmosphere along with hydrocarbons!
Come on we are better than this!!
This article’s conclusions are misleading. Leaded aviation fuel is the primary contributor to lead in the atmosphere. There’s a study from 2011 (Published in the national library of medicine if I remember correctly) that found increased lead content in the blood of children living near airports. Any amount of lead ingestion is considered unsafe, unfortunately.
I am hopeful a good solution comes through relatively soon. There’s been good progress from what I’ve seen. If nothing else, its a helpful exercise in chemical engineering that should have increased performance benefits for most engines.
My concern isn’t with the health hazards; it’s with the availability of lead for the fuel in the future. As far as I know there’s only one supplier remaining, and if they go belly up we’ll have an unleaded future want it or not. I’ve always thought we should be working toward developing diesel engines that could replace our current Lycomings and Continentals, and burn Jet fuel—which isn’t going away anytime soon.
Water injection
No amount of lead exposure is safe
It lowers IQ full stop
I’m voting for option #1, continue as usual, when someone can prove beyond a shadow of a doubt with facts that leaded fuel has screwed up a lot of people and maimed and killed them because there is lead floating around in the atmosphere maybe then I will opt for change. So far since I can remember back in the 40s and 50s in the railroad yards, in the truck industry, everywhere you turned there was exhaust from something that was burning leaded fuel of some type, to date, and I’m saying the last 60 years plus, I know of no one being effected dangerously from burned fuel lead in the atmosphere. Since this whole ordeal started many many years ago, nothing has changed, and we are all still here and worrying about something that actually has no interest or validity. So if we go to unleaded fuel for aircraft, what will that actually change ??? from what we have today ??? Besides the price of fuel for aircraft unnecessarily , that and more expensive changes in the aircraft engines for absolutely no reason at all. leave it alone, please.
When they removed led from cars, they harden the valves & rings in the car’s engines. That stopped the knock in the engines of those cars. So, I Rember this also there was a gestation that came out with white gas. I Rember that I had a older car that knocked. Then I leant out my car to a Frend. When he returned the car, it did not So I asked him what he did to my car to stop the knock in the car. He said he put white gas in it. From then on that is whit i used! Hey the car drove better & I kept putting white gas in even though it was more expensive. So go back in the pass & harden the valves & rings in the engines. Probably this will rise the cost of fixing the over hall of the engines in the over hall of the engines in the planes. I do not have better solation. so Mabe it is a solation..
There are in fact studies that find elevated blood lead levels in children living near US airports. For example: https://pmc.ncbi.nlm.nih.gov/articles/PMC3230438/#:~:text=Results%3A%20Our%20results%20suggest%20that,within%201%2C000%20m%20of%20airports.
And there is strong evidence of high risk exposures to pilots and mechanics.
Given these risks and based on 20 years of experience in environmental health I believe the benefits of replacement fuels is legitimate and bases on good science.
Curious. Have blood lead levels of ramp workers ever been tested?
Good question. None that I could find.
By the way, great article Ben!
I like option 1 but it should include the down sides of fouled plugs, sticky valves and oil changes in the 25-50 hour range rather than 100 hours (as Lycoming permits on unleaded fuel).
Slowly removing TEL via option 2 will result in some engines (e.g. turbo/supercharged) eventually having their timing retarded to avoid detonation.
A great question would be “how much TEL can be removed while retaining detonation margin?”
What a mess. So they don’t want to follow the science but prefer to follow suspisions. Thank you EPA ostriches.