G100UL - fuel leak

[A64Pilot]

I’ve been burning 87 Octane car gas in my C-140 for years, the 140’s fuel vent system is 2 small holes drilled into the tractor style fuel caps, as such if you fill them up they will siphon fuel out in flight.

Both my fuel tank covers that are painted with Jet-glo are stained a yellowish brown, but it will polish out, or did a few years ago the one time I did

Edited December 27, 2024 by A64Pilot

[redbaron1982]

I have relatively little experience with 100LL (2 years / always same airport), but I haven't seen any permanent deterioration of my J paint by exposing it to LL. My J paint is quite bitten up and it's original (1985).

My LH wing wipes LL from the sump drain, and after two years it really got stained with the blue dye, but it quickly came off rubbing it with some fresh LL.

So, at least in my airport, LL formulation is not harsh to paint at all.

[T. Peterson]

57 minutes ago, A64Pilot said:

I keep bringing this up, but all this angst of “we must have an unleaded 100 Octane fuel” just isn’t the case, not at least for non forced induction aircraft anyway and I suspect turbo aircraft would be fine too in cruise.

It’s been done widespread since WWII, called ADI or anti detonation injection. It’s simple alcohol / water injection, trigger points for injection are often manifold pressure above 25” or cyl head temps above 400F

https://www.avweb.com/features/the-return-of-anti-detonation-water-injection-adi/

https://generalaviationnews.com/2012/05/22/adi-bridging-the-octane-gap/

https://www.autofuelstc.com/news.phtml/E2F118E7/anti-detonant_injection

With it you burn car gas, no big deal, no melting paint, swelling O-rings etc because people have been burning car gas for decades, I have anyway, but on low compression engines

OR just remove the lead from 100LL and burn it with ADI, why not do that?

Very interesting articles. Sounds like it may be an extensive rework of our airplanes and will eat into our already weak useful load, but at least it would be a real STC and not a government boondoggle masquerading as one.  Also has a proven track record over years. In light of this other debacle maybe it will pick up momentum. I hope so.

Thanks for your input. I always enjoy reading your posts.

[T. Peterson]

10 minutes ago, A64Pilot said:

I’ve been burning 87 Octane car gas in my C-140 for years, the 140’s fuel vent system is 2 small holes drilled into the tractor style fuel caps, as such if you fill them up they will siphon fuel out in flight.

Both my fuel tank covers that are painted with Jet-glo are stained a yellowish brown, but it will polish out, or did a few years ago the one time I did

What all was required practically and legally to allow using car gas?

[donkaye]

7 hours ago, IvanP said:

Wow, that is quite substantial staining, considering that you just recently started using this fuel. 

Did you, by chance have the opportunty to borescope your cylinders since you started using G100UL? Any visible changes on the exhaust valves? I have heard that turbocharged engines do not like this fuel much (detonation and exhaus valves burning), but that is merely anecdotal report from unverified source. It would be nice to have first hand expeirence from a Bravo owner.  

In another post I mentioned the % G100UL to 100LL and the % was less than 50% on each case, so at this time there probably wouldn't be any significant change.  I was looking forward to the real benefits of G100UL when it became so readily available that I would always have the choice to use it.  With 100LL being used mostly in my plane borescoping it wouldn't be very valuable at this time.

Knock on wood, there hasn't been so much as a hiccup in the engine and it runs smooth as silk for a Lycoming.

[PT20J]

27 minutes ago, T. Peterson said:

What all was required practically and legally to allow using car gas?

https://www.autofuelstc.com/

[A64Pilot]

22 minutes ago, T. Peterson said:

Very interesting articles. Sounds like it may be an extensive rework of our airplanes and will eat into our already weak useful load, but at least it would be a real STC and not a government boondoggle masquerading as one.  Also has a proven track record over years. In light of this other debacle maybe it will pick up momentum. I hope so.

Thanks for your input. I always enjoy reading your posts.

It’s an extraordinarily simple system, if you have ever played with Nitrous Oxide in cars it’s very similar, simple plate that goes between the carb or servo and intake “four bolts” and one hose that connects to the plate that I’m sure has a spray bar in it, the hose connects to an automotive electric fuel pump that connects to a tank. The “brain” made apparently by EI now monitors two things, cyl head temp and manifold pressure, either or both above set point, pump is turned on.

That’s it. Other than not being approved of course I could build one myself in a day.

Many Ag guys do it in particularly G6 Garrets, in the Garret it’s EGT that’s the limiting factor, it’s why yiu can’t keep pushing the power lever forward, inject water and yiu get an instant drop in EGT so yiu can push the lever further forward making more power for takeoff.

Car guys, ones that run high boost anyway have been doing it for years, apparently they often run windshield washer pre-mix, seems the cheap blue stuff is just the right mix of alcohol and water

https://www.dragzine.com/tech-stories/engine/get-schooled-water-methanol-injection-101/

https://www.holley.com/blog/post/the_science_behind_why_water-methanol_injection_works_so_well/

[GeeBee]

1 hour ago, A64Pilot said:

I keep bringing this up, but all this angst of “we must have an unleaded 100 Octane fuel” just isn’t the case, not at least for non forced induction aircraft anyway and I suspect turbo aircraft would be fine too in cruise.

It’s been done widespread since WWII, called ADI or anti detonation injection. It’s simple alcohol / water injection, trigger points for injection are often manifold pressure above 25” or cyl head temps above 400F

https://www.avweb.com/features/the-return-of-anti-detonation-water-injection-adi/

https://generalaviationnews.com/2012/05/22/adi-bridging-the-octane-gap/

https://www.autofuelstc.com/news.phtml/E2F118E7/anti-detonant_injection

With it you burn car gas, no big deal, no melting paint, swelling O-rings etc because people have been burning car gas for decades, I have anyway, but on low compression engines

OR just remove the lead from 100LL and burn it with ADI, why not do that?

The problem with  ADI is if it fails, you won't know until engine damage is done. It is often just a solenoid that opens at a certain trip point, but you won't know flow failure until engine detonation occurs. With jets you can see the flow (or lack there of) before you throttle into overtemp, but on recips without someone carefully monitoring (like a flight engineer) things can go awry very, very quickly. Equally so, on multi-engine airplanes you have a good clue when one spits out the bit, but on a single there is little to compare that the flow has failed until way too late even with EGT and CHT.

If we had an ECM to monitor and reduce the engine throttle it could work nicely.

[A64Pilot]

31 minutes ago, T. Peterson said:

What all was required practically and legally to allow using car gas?

In the 140, it’s was an $85 STC, there are a couple of STC’s Peterson charged $1 per HP I think. I think you’re supposed to have a label by the fuel filler that says MOGAS is OK, but I don’t. In truth most little airplane guys just run it and don’t bother buying the STC

No modifications to the aircraft, although some aircraft do require mods. Maule has to have a fuel pump and I think a vent to prevent vapor loc. So it differs by airframe

[A64Pilot]

20 minutes ago, GeeBee said:

The problem with  ADI is if it fails, you won't know until engine damage is done. It is often just a solenoid that opens at a certain trip point, but you won't know flow failure until engine detonation occurs. With jets you can see the flow (or lack there of) before you throttle into overtemp, but on recips without someone carefully monitoring (like a flight engineer) things can go awry very, very quickly. Equally so, on multi-engine airplanes you have a good clue when one spits out the bit, but on a single there is little to compare that the flow has failed until way too late.

If we had an ECM to monitor and reduce the engine throttle it could work nicely.

You do know, even back in the day there was a light that came on if water pressure dropped below set point when system was on, I think you got a green light when system was on and you had water flow and a red light when system was on and limited or no flow.

I know Rob Roberts owner of EI very well, I’m certain that his “box” monitors pressure and turns on the second pump if necessary and alerts the pilot, but I have not seen the new system.

In truth you really can run premium car gas without harm most times, it’s only if you get that stupid high cyl head temp that Lycoming allows that you get detonation, but Cert rightfully so requires a healthy margin

Way back in the 70’s I think University of Tennessee ran a C-310 on what then was called Gasahol in one engine for hundreds of hours. Dr Ralph Kimberlin who was my Civilian Test Pilot mentor was part of the program. It may have been a 421 not sure.

Without ADI you do have to have a very different Cyl head temp redline though, and I’m sure you don’t have the margin 100LL gives you, but with ADI that margin is even larger that without ADI but running 100LL.

Edited December 27, 2024 by A64Pilot

[GeeBee]

2 hours ago, donkaye said:

I usually use self serve and there is no protective matt for 100LL.  I never noticed any staining before on the wing.  100LL stains blue and I have never had any issue removing it, but only occasionally does it overflow.  I immediately wipe the wing when that happens.  This color is the color of G100UL.  As I mentioned in an earlier post, I still intend to use G100UL, but will use extreme care with it.

Don, have you considered using 3M paint protection film like they use on cars around the fuel fill. It would protect both against nozzle dings and paint staining. 

[GeeBee]

11 minutes ago, A64Pilot said:

You do know, even back in the day there was a light that came on if water pressure dropped below set point when system was on, I think you got a green light when system was on and you had water flow and a red light when system was on and limited or no flow.

I know Rob Roberts owner of EI very well, I’m certain that his “box” monitors pressure and turns on the second pump if necessary and alerts the pilot, but I have not seen the new system.

In truth you really can run premium car gas without harm most times, it’s only if you get that stupid high cyl head temp that Lycoming allows that you get detonation, but Cert rightfully so requires a healthy margin

Way back in the 70’s I think University of Tennessee ran a C-310 on what then was called Gasahol in one engine for hundreds of hours. Dr Ralph Kimberlin who was my Civilian Test Pilot mentor was part of the program. It may have been a 421 not sure.

Without ADI you do have to have a very different Cyl head temp redline though, and I’m sure you don’t have the margin 100LL gives you, but with ADI that margin is even larger that without ADI but running 100LL.

Gasohol has all kinds of water absorption problems. Yeah the light comes on with flow, but what happens if the simple pump quits or the feed stops right in the middle of WOT operation. You can't pull the throttle back fast enough before damage occurs. In a transport multi engine no big deal, in a single you could be dead sticking.

[gabez]

2 hours ago, donkaye said:

I usually use self serve and there is no protective matt for 100LL.  I never noticed any staining before on the wing.  100LL stains blue and I have never had any issue removing it, but only occasionally does it overflow.  I immediately wipe the wing when that happens.  This color is the color of G100UL.  As I mentioned in an earlier post, I still intend to use G100UL, but will use extreme care with it.

welcome to the club!! 

[donkaye]

8 minutes ago, GeeBee said:

Don, have you considered using 3M paint protection film like they use on cars around the fuel fill. It would protect both against nozzle dings and paint staining. 

Based on the area disturbed, that probably wouldn't work for me.

[Marc_B]

I have a flapper on my filler neck and many times fuel has splashed off it onto the wing if the pressure of the pump is high. I’ve never had any damage to the paint and never had any staining from this even when I didn't have a rag available and just let air dry.  The paint around my wing is decent but definitely not perfect and some paint chips.

Prior to getting my tanks resealed in 2022 I had a few seeps and runs that had blue staining down the seam under the wing. I had them resealed at Weep No More and Paul was easily able to clean the stains off and now you can’t even tell where these used to be.

This appears to be a MUCH different process 

[A64Pilot]

11 hours ago, GeeBee said:

Gasohol has all kinds of water absorption problems. Yeah the light comes on with flow, but what happens if the simple pump quits or the feed stops right in the middle of WOT operation. You can't pull the throttle back fast enough before damage occurs. In a transport multi engine no big deal, in a single you could be dead sticking.

It’s not a single pump, it’s two pumps on different electrical busses, and there is an ECU to control them, made by Electronics International, not a Chinese sub contractor. I’m certain though that it can’t reduce throttle, that level of control is very difficult to Certify and frankly I wouldn’t want it, I don’t want some box protecting the engine right up to impact.

Detonation isn’t by any far stretch of the imagination instantaneous, in fact not that I would but based on experience I’m sure I could run car premium and not detonate, it’s illegal of course and the safety margin isn’t there.

100 LL is required to run 500 deg cyl heads temps, in very hot weather, at maximum oil temp and the worst possible mixture AND have some cushion.

However it DOES happen on occasion even with 100 LL, often to one cylinder and that admittedly confuses me

But anyway there is plenty of time to make a decision of what to do if both pumps on different electrical busses fail, there are shed loads of single point failure systems we fly with now, ADI wouldn’t be one of them.

We can try to denigrate anything, but as 100 UL isn’t apparently simple or one of the major players would have come up with it years ago, I don’t see any reason to not go with ADI, and my preference would be with 100 LL with the lead removed as that way you keep the quality control and nearly unlimited storage life etc that we currently have, just without the lead, it couldn’t cost more that the same product with lead, and there would be no realistic reason to not use the same infrastructure to deliver, store and dispense it. Other than the 20 lb or whatever it is reduction in useful load I don’t see the downside to ADI, it even keeps the combustion chamber and plugs very clean.

9K is steep though, but it is an airplane I guess with some parts you would think that would cost next to nothing costing a lot.

But it’s 9K one time whereas I suspect that any replacement to 100 LL will be significantly more expensive at every fill up.

BUT, and here to me is what’s important, it’s another option, anytime your the sole source of a needed product (NBS springs come to mind) the opportunity to price gouge is possible, not that I’m saying George would, but he not the producer or seller, but if there are alternatives that helps keep the gouges at bay it helps keep gouging from happening, I don’t like monopolies. (NBS again)

Personally I would go with ADI myself as I both trust it, but also I wouldn’t have to have a fuel that in my opinion no one really knows what the long term results will be, but in particular we know 100LL, without the lead it shouldn’t change much, however I think without an additive to prevent it unless we go to hardened seats we will have valve recession from anyones UL, just exactly like we did with cars when we went to UL.

I’d say Auto fuel, but it changes often and with the seasons and has storage issues etc. best I think to stick with current Avgas, but having Auto fuel as a back up is nice. I like options  

Edited December 27, 2024 by A64Pilot

[A64Pilot]

It’s been years ago, but when I first started burning car gas in the 140, I did quite a lot of searching for accidents attributed to alcohol in fuel, searching the NTSB database, certain that I would find several as Experimental's can run anything they like and many run car gas even in aircraft without the STC, not everyone tests for alcohol and often alcohol free isn’t available more burn it than we would suspect, same guys likely fly out of annual etc. too.

I couldn’t find even one, which really surprised me, I expected several

[Pinecone]

16 hours ago, T. Peterson said:

I think we have come to an impasse and will just agree to disagree. No malice and no heartburn. 
I do have a question: Do you and @GeeBee have any imagination that G100UL might possibly be a greater health hazard than 100LL?

That is entirely possibly.  History is full of changing from one product due to hazards only to find out later that the new product is as bad or worse.  

I have never said that lead from aircraft engines is a hazard.  But that will not stop people from using it to rile up others to close airports.

History is also full of examples of over reaction to a minor or limited hazard.

[Pinecone]

17 hours ago, redbaron1982 said:

spec that any fuel manufacturer can follow? Or each fuel manufacturer have their own proprietary formulation that meets certain specs?

The latter.  They can blend, within certain constraints, their own formula.  

George and other have mentioned this when it comes to 100LL not being the same from region to region depending on the base alkylate from that refinery.   
 

G100UL sets a minimum spec for the base alkylate.

[Pinecone]

14 hours ago, A64Pilot said:

With it you burn car gas, no big deal, no melting paint, swelling O-rings etc because people have been burning car gas for decades, I have anyway, but on low compression engines

OR just remove the lead from 100LL and burn it with ADI, why not do that?

Has anyone tested O-rings in the current blends of MOGAS?

100LL without the lead is 94UL (pretty much).

But who is going to develop the STC for all the airplane needing an ADI system.  And BTW, many turbo aircraft cruise at over 25" manifold pressure.

[Pinecone]

12 hours ago, GeeBee said:

Gasohol has all kinds of water absorption problems. Yeah the light comes on with flow, but what happens if the simple pump quits or the feed stops right in the middle of WOT operation. You can't pull the throttle back fast enough before damage occurs. In a transport multi engine no big deal, in a single you could be dead sticking.

And on a single, the option of pulling throttle back could also put you on the ground, off airport.

[A64Pilot]

47 minutes ago, Pinecone said:

Has anyone tested O-rings in the current blends of MOGAS?

Depends on if the FAA required it for the STC, one certainly hopes so. But even if they did that was what 40 years ago, and is Auto gas even remotely the same now, do you have to check every possible change? I went down a rabbit hole Certifying a turbine airplane for Bio -Diesel, can’t be done and I knew it, reason is there is no definition of Bio-Diesel, it can be pretty much anything that will burn, so how do you Certify to that?

Auto fuel I think will always be problematic as it changes formulation based on emissions, climate and other reasons. How could you test formulas that don’t yet exist?

100LL without the lead is 94UL (pretty much).

I thought so, but don’t really know, assumptions can sometimes get you in trouble

But who is going to develop the STC for all the airplane needing an ADI system.  And BTW, many turbo aircraft cruise at over 25" manifold pressure.

Been done years ago by Peterson, does require new models to be added though. I suspect though that car gas due to vapor lock issues etc could get difficult on some, especially low wing aircraft. That is where I suspect that 94UL wouldn’t be an issue. The initial reason for ADI was mostly due to fuel cost, but fuel came down and ADI for most just wasn’t necessary, now with lead going away, the need for ADI exists again

 

Edited December 27, 2024 by A64Pilot

[A64Pilot]

57 minutes ago, Pinecone said:

And on a single, the option of pulling throttle back could also put you on the ground, off airport.

Back to two pumps, on different busses, but losing a Mag could also, or a clogged fuel injector or strainer  or any number of a great many other issues. I would tell you that the likelyhood of a fuel that causes O-rings to swell is far more likely to cause an engine failure as there are a great many “rubber” and plastic components in an aircraft fuel system.

My C-140 would likely be OK as the only plastic or rubber in it is the fuel level indicator floats and maybe a cork gasket where they go into the tank, but my Mooney is full of the stuff from the servo, fuel divider, fuel flow transducer, both fuel pumps, strainer, fuel selector to say nothing of my bladders or everyone else’s sealer. O-rings are I think the least of the possible problems 

Unless the guy who did the video snuck in MEK or something into his tests those simple backyard tests are enough to keep me away. If I lived where it was the only option I’d pull my fuel trailer to where I could buy 100 LL, sell the Mooney or quit flying Certified aircraft I guess or buy something Certified to burn car gas. I think Rotax are allowed?

Edited December 27, 2024 by A64Pilot

[Will.iam]

19 hours ago, Pinecone said:

The problem with these studies is the lack of control groups.  Where do you find enough people with a demonstrated ZERO exposure?

Well they could use the people like me that are in the aviation field professionally and i used to use 100LL to wash parts with “gasp” no gloves on as a kid and young adult before this became a nono. Went to a holistic doctor that just knew i had lead in my body but when the lab results came back he was shocked i did not. Either the issue is overblown or my body seems to be able to remove what lead i do get into my system. My A&P routinely washes his hands with 100LL to this day. He is 78 been doing it all his life. He said if it has not killed him yet it’s not going to now. 

[gabez]

is the diaphragm in the flow divider be affected by the G100?