In my last column, “The panic about unleaded fuels,” I wrote about the need for a new specification for unleaded 100 octane fuel that is agreed upon by all parties, such as from ASTM.
In that column, I noted: “The advantage for an ASTM specification is that it would have the blessing of the engine manufacturers as to their warranties. An ASTM spec also has liability protection that an STC does not.”
I received a number of comments on that column, including one from ASTM officials explaining that my statement about an ASTM approved fuel was incorrect because ASTM does not approve fuels. The organization manages the specification, but does not approve any products.
This is a legal thing and I understand their concern.
I was incorrect in my statement — I meant to state that it was a product approved to an ASTM spec and not an ASTM approved product.
But this brings up an interesting question: Who will actually “approve” any new unleaded fuel and what does that approval mean?
I also received an email from officials at General Aviation Modifications Inc. (GAMI), which earned STC approval in September 2022 for its unleaded G100UL avgas.
They pointed out that my statement that all engine warranties may not be covered if an aircraft owner uses an STC-approved fuels was not correct. They said that that would be illegal and listed several laws that addressed that.
I admit that the comment came from an engine manufacturer’s representative statement at an open meeting and may not be company policy.
Another statement I made concerns product liability with an STC approval versus an ASTM specification.
GAMI officials pointed out that their fuel suppliers and distributors have contacted their insurance companies and none of them had any concerns.
This is, obviously, a good thing, but in case of an engine failure caused by, say, the lack of lead for exhaust seats, the lawyers will go after the holder of the STC, not the distributors or manufacturers — as long as the product meets specifications.
So, the oil companies’ liability is limited to keeping the product on spec the same as it is now for 100LL.
The last point has to do with approval by STC vs. meeting an agreed-upon specification.
About 30 years ago, Phillips Petroleum wanted to improve the anti-wear performance of its 20W50 X/C oil. The company added a small amount of a zinc additive to improve the performance of the oil and called it X/CII.
But since the SAE/MIL spec for the product called for zero ash, the oil would not pass the approval process. So, the company got it approved by an STC.
When problems caused by the additive started to pop up, the STC provided no protection and I believe the company lost every case.
The way I see it, an STC approval is just legal permission to sell a product — it will not provide any liability support in case of a problem.
If a product is qualified against an ASTM specification, that does not provide legal liability protection. But in a court of law, it will carry the support of an industry agreement that the product should meet the requirements of all general aviation aircraft as opposed to that of just the STC holder.
Some way and somehow, the whole general aviation industry and the EPA needs to stand up — and stand behind — the use of 100UL fuels in the entire GA fleet.
Speaking of Phillips Petroleum, I understand it has dropped out of the running to produce an unleaded 100 octane fuel through the FAA’s Piston Engine Aviation Fuels Initiative (PAFI) testing program.
Do you ever wonder why none of the major oil companies are interested in accepting this challenge?
TEL was clearly introduced as an octane booster, the dry lubricant benefits of the resulting Lead Oxide was an unintended consequence, a well documented feature that in my opinion allowed great development in IC engines for 100 years.
Using stellite seats, we seem to be able to do without it IF THE SEAT TEMPERATURE is not too high. This is why the Rotax engine is so successful with unleaded fuels. It remains to be seen if the air-cooled cylinder heads can handle the loss of lubrication from TEL or any other such metallic compound.
Plug fouling is a sign of poor combustion quality and is not just caused by lead.
I have not cleaned a plug in 7000hrs and I don’t hear from any of my 11000 ignition customers that they ever need to clean their plugs using 100LL.
I’d never go 100 hours between oil changes in ANY engine, no matter what the engine manufacturer says! And, speaking of sludge, as was learned by Lycoming about 30 years ago, NEVER use synthetic engine oil and leaded fuel!
Ben, why should we stand behind 100UL? Why do you think the EPA will stop at that? Cars run UL and we are being forced to buy electric pieces of junk. Just witnessed ~20 Tesla’s at a charging station with their owners sitting in their cars trying to charge them when it’s 112 deg F outside and their air conditioners running! How does that improve the environment??? The best and the brightest have tried to find an adequate replacement for 100LL the past 50+ years and all have failed, it’s time for AOPA and EAA to stand behind 100LL. An 100LL replacement has as much credibility as the Covid vaccine has at preventing Covid. My local airport is now required by local politicians to make UL available but they can’t figure out how to install the system and meet all the current regulations including the required vapor recovery system so pilots can’t actually use the UL but the politicians took credit for making it available. Stop the insanity! And if you have to change your oil and clean lead off plugs every 25 hours you are definitely doing something wrong.
Looking at Rotax SI-912-016-r4, if you use 100LL they say to change the oil and filter every 25 hours. They state that this is due to the oil contaminants and sludge .
If unleaded autogas is used the oil change interval can be 100 hrs.
My engine with old cylinders was using 1 qt every 3 hours, and the oil analysis showed lead levels of about 1,00 ppm.
With new cylinders, the oil use dropped to 1 qt every 10-11 hrs, and the lead level rose to 3,000 ppm. After a few 50 hr oil changes I found 3 stuck exhaust valves.
I now do 25 hr oil changes to get the lead down to the 1,000 ppm level again.
Even with aggressive leaning on the ground and in flight, I still get lead in the plugs, which I clean during the annual, with about 80 hrs from the previous cleaning.
TEL is nasty stuff.!
I remember in the ’80s that MTBE was used for a while, until it was found to contaminate ground water if a tank leaked. So, we got ethanol , after the ‘renewable’ fuel mandate.
Dave, I’m with you 100%!! Their Krat ideology is pushing this nonsense. These old, air-cooled piston jobs (old technology), were made to run on high octane leaded fuel. Period. Why anyone would be interested in burning something other than that is beyond me. The UL fantasy will NOT improve the environment, it will be more expensive at the pump (isn’t 100LL expensive enough?), and it will cause damage to valves that do not have the hardened seats. Plus, we’ll all need STC’s to burn it. So, who’s going to pay for all of this?! And for what?! Pretending that GA has any impact on the environment is practically laughable. It’s just another sham that we’ll all be paying for. I’m a realist though. These people will get their way. It will cost us plenty. I know that sooner or later I’ll find myself searching for 100LL and eventually it just won’t be available anymore – at any price. Again, all for what..
Actually, most of the low compression piston aircraft engines were certified to use 80/87 octane avgas. I have an autogas STC for 87 octane. BUT, no ethanol. So, I’ve never been able to use autogas here in California, since, by law, all auto gas has 10% ethanol.
BRAVO, Dave! Spot on! EPA can go kick sand.
Well with only one company in the world making TEL it would seem prudent for the world of 100LL aviation to have a backup plan for a viable replacement before that day comes when TEL is no longer made. Plus I think it is the morally correct thing to do since lead isn’t good for humans in any amount and especially for very young humans.
As for EVs and the 112° temps maybe as the numbers of EVs increases and the number of ICE cars decreases the climate change will begin to slow down and we won’t be passing on to our great great grandchildren a hotter and less livable planet.
Mr. Strong,
You had me until your second paragraph. Then I realized that you cannot be helped.
I wanted to bring to light the topic of TEL as a lubricant. It seems the myth of this continues. TEL was never intended to be a lubricant initially. In the ’80s we saw issues moving from leaded gas in valves in which manufacturers responded with updated valves and valve seats. I would propose a similar circumstance would present itself here. I have read that Lycoming has already made some changes in their valve seats. Can anyone confirm this. I think it was a M Bush podcast which mentioned this.
I would also question review of the design documents that specify that exhaust valve be required to operate in a lead atmosphere to maintain any form of integrity. If that spec doesn’t exist, the plaintiff got no case.
This article kind of points to the need for the government to just outlaw lead in gasoline and put a drop dead date for its removal. Once that happens, the real solutions will come about Otherwise, we will continue the 30 years of infighting that will never produce a solution. California will probably have to lead here As they might be the only state that has a backbone.
Done…The FAA re-authorization bill, passed in May;
” 100LL availability: Requires airports that offered 100LL aviation gasoline for sale in 2022 to continue offering the sale of 100LL until 2030 or the date on which the FAA certifies an unleaded aviation gasoline alternative is available for purchase or use by GA aircraft operators.May 15, 2024 “.
So, they’ve got 6 years to get an unleaded fuel certified.
California had to scrap their pending bill to eliminate 100LL.
You do know it doesn’t require 100 LL to be offered until 2030. If a Suitable 100 octane Unleaded fuel becomes available and is used the 100 LL requirement can go away.
Yup, that’s what the statement says that I quoted.!
Sooner is better, I hate cleaning the lead from 12 spark plugs, and changing oil a 25 hrs due to the lead buildup.!
The only ones who continue to matter in this discussion are Lycoming and Continental, and they will remain outside the discussion until forced to engage by market demand or law. In the mean time, everything else is an alteration to a type design.
I spoke to Lycoming at Oshkosh a couple years ago. I specifically asked about the ongoing unleaded fuel debate. The person I spoke to stated the lead was in 100LL only as an octane booster, not as a lubricant. He also stated any lubrication benefit was simply minor and not required for their engines.
YMMV
It is bad to see this article push the lubricant myth and then tie it to the legal system. Currently the Engine manufacturers are also saying that the lead in the gasoline will shorten the TBO time by a significant amount adding significantly to the cost of flying and possibly reducing safety, which includes fouled plugs.
The TEL does build up on the plug electrodes, and a lead ball can short a plug, which prevents it from igniting the fuel. But the TEL doesn’t foul a plug as oil and excess fuel can.
The other big problem with TEL is that it gets into the oil with blow by.
The lead in the oil then gets deposited on the exhaust vale guides and will cause the valve to stick, either open or closed.
If it sticks closed it will bend the pushrod and break the pushrod tube.
Then oil is lost through the broken tube and the engine can seize after a bearing spins and throws a con rod, if all the oil is lost.
See Lycoming SB 388C;
https://www.lycoming.com/content/service-bulletin-no-388c
I’ve always found those same issues in the automotive world. It seems to be the same core problem which is lack of fuel control. In automotive it’s been lack of mechanic’s knowledge dealing with carburetors, especially chokes. Today it’s dealing with fuel injection components going out of tolerance a little here and a little there..
On the aviation side it’s the pilot, who has simple control of fuel management. Which like everything else is a heated battle of wit and misinformation as to what’s correct..
Fouled plugs or galled valves are optional..