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RV-14 Flight Trial Report - 100-octain UL avgas

jsisk

jsisk

Member
For those of you who are interested in the eventual transition to an unleaded replacement for 100LL avgas, attached is a pre-release copy of my report for the December Aviation Consumer magazine on flying G100UL in the White Lightning RV-14 on October 1st. Also included as a cover is Larry Anglisano’s introductory remarks. As you will read, it worked great. BTW, I landed with 11 gallons or G100UL remaining in the right tank. I later added an equal amount of 100LL to test the fungibility of the fuel. There was no detectable or measurable differences in operation.

Perhaps we are inching closer and it will not take until 2030.

This PDF may be circulated as long as attribution is given to the publisher, Aviation Consumer magazine.
 

Attachments

  • December 2023 Aviation Consumer G100UL Flight Trial.pdf
    1.5 MB · Views: 343
Thanks for sharing this. I REALLY hope a 100 octane unleaded fuel is widely available by the time I finish my -14A. I don't want to muck up the internals of a new engine with 100LL.
 
Most people are convinced G100UL will work fine in their engine - as this article supports.

But, as with other news about G100UL, this article does not mention any projected end user cost for the fuel.

Carl
 
Not apples to apples, but I have run 93 UL for past 500 hrs. Cleaner oil, lower cost, 3.72gal today, spotless massive plugs, nice looking exhaust valves. Its 2 miles to the fuel station. Works for my O320 D1A.
 
The author of the article wrote that he add the gammi fuel to the airplane limitation before getting the "FAA inspection and licensing". I am assuming he means airworthiness certificate. But then I think we can put gammi fuel in the existing RV by having the sticker on the fuel receptable that it can use Gammi fuel. Am I right about this?
 
Yes, I mean airworthiness certificate. I believe a change in fuel is considered a major alteration, so aircraft would need to go back into phase 1 testing to establish that it is safe. With an already approved fuel, that should not be a big deal. The L/R tank comparison to 100LL makes similarity testing pretty simple. Revise fuel limitations in POH and fuel filler placards. My placards simply say "100 Octane Avgas".
 
Projected pricing for G100UL is 50-80 cents more than 100LL. Over time, 2 significant logistical issues should offer cost savings. There are only a few producers of avgas, mostly because of the Pb contamination. Rail cars, barges, truck tanks, etc. that haul 100LL cannot carry anything on their return trip. With unleaded fuel, those infrastructure components can haul fuel both ways. Also, I think we will see more fuel blenders with lead contamination no longer a barrier to entering the market, so transportation distances will shorten and more competition.
 
I'd happily pay $1 or $2 more per gallon to prevent lead build up in my $60,000 engine.
 
bertschb said:
I'd happily pay $1 or $2 more per gallon to prevent lead build up in my $60,000 engine.
Click to expand...

Not sure what lead build up you're referring to...

Decalin is the additive that is commonly used in Rotax 912 engines that are run on 100LL. Went through a bunch of it when I had the AirCam.

There's another, similar additive, don't recall the name.

And y'all have probably seen that UND went back to 100LL to preserve the valves.

There's a whole lot of science/engineering that goes into no-lead avgas, especially when you consider that all the mixtures of gasolines have to work in any combination. The real issues are not whether something can be made to fly for an hour or two or ten, but longevity and reliability. And reliability is measured not in hours, but in thousands of hours.

Don't get me wrong -- I breathe air like everybody else, and I'd be real happy if tetraethyl lead went away. But if my RV-9A ends up in a field somewhere due to no-lead avgas, I will not be celebrating.
 
Ed_Wischmeyer said:
Not sure what lead build up you're referring to...
Click to expand...

I wasn't very clear in my post. Sorry about that. My point is leaded fuel doesn't burn as cleanly as unleaded fuel. I'd prefer cleaner engine internals (e.g. oil, valves, plugs, etc) all else being equal.
 
Ed_Wischmeyer said:
Not sure what lead build up you're referring to...
Click to expand...
I think most of us have experienced lead fouling, buildup on valve seats, etc. I know I have.
And y'all have probably seen that UND went back to 100LL to preserve the valves.
Click to expand...
Yes, although that was 94UL - applies / oranges? Hard to know given that it's not one of the currently proposed full octane equivalent 100LL replacement fuels.
The real issues are not whether something can be made to fly for an hour or two or ten, but longevity and reliability. And reliability is measured not in hours, but in thousands of hours.
Click to expand...
For sure. Time will tell.
Don't get me wrong -- I breathe air like everybody else, and I'd be real happy if tetraethyl lead went away. But if my RV-9A ends up in a field somewhere due to no-lead avgas, I will not be celebrating.
Click to expand...
Given what we know so far, I think that's not the likely scenario - it's more whether or not our engines make TBO without increased valve wear etc. Long term, real-world testing will be the key.

I do agree that the "fleet" ought not to be the guinea pigs in all this. Testing on engine stands is one thing but I'd sure feel better if the "entities" would just go and fly a bunch of planes with different engines to TBO, along with equivalent "control" aircraft running 100LL. Expensive, sure. But the alternative is, we're all the ones doing that.
 
Is that really a thing? I feel like nobody is going to care if you pump 100LL or 100… All the certified planes need is to buy the GAMI STC, at worst you’d have to buy the STC, at best you just pump what you want. How would anyone ever know or care?
 
Majorpayne317641 said:
Is that really a thing? I feel like nobody is going to care if you pump 100LL or 100… All the certified planes need is to buy the GAMI STC, at worst you’d have to buy the STC, at best you just pump what you want. How would anyone ever know or care?
Click to expand...

...and what would a test look like that has not already been done by GAMI?
 
Majorpayne317641 said:
Is that really a thing? I feel like nobody is going to care if you pump 100LL or 100… All the certified planes need is to buy the GAMI STC, at worst you’d have to buy the STC, at best you just pump what you want. How would anyone ever know or care?
Click to expand...

What exactly would buying an STC do? Your experimental aircraft does not have a Type Certificate to Supplement. Even if you bought it, it would still be wrong.

Whatever is in your Ops Manual is what you use. You should have specified Octane only. If you put LL then that’s what you bound yourself to. It’s the reason certified aircraft will need an STC because the TC specified the LL lead.

It’s an exercise in correct paperwork to maintain the airworthiness certificate.

Again, Mel has said it many times to leave off the LL. Your placards and ops manual need to match. All that 100LL stuff in your books that YOU put there has painted you into a paperwork corner.
 
N82VM said:
Whatever is in your Ops Manual is what you use. You should have specified Octane only. If you put LL then that’s what you bound yourself to. It’s the reason certified aircraft will need an STC because the TC specified the LL lead.

It’s an exercise in correct paperwork to maintain the airworthiness certificate.

Again, Mel has said it many times to leave off the LL. Your placards and ops manual need to match. All that 100LL stuff in your books that YOU put there has painted you into a paperwork corner.
Click to expand...

First of all, there's nothing IN my Operating *Limitations* document that specifies anything about the fuel type. The only thing it says is that labels on the aircraft have to be correct.

Unless your OpsLIMS say something different, just change the label if you need to. It's correct now, changing it to read "100" instead of "100LL" it would still be correct.

Jeez....

ETA: from the post that YOU linked to:

...try to avoid the temptation to ad (sic) "LL" to your labeling.
Click to expand...
(Emphasis added)
 
Last edited:
Conditions and Limitations

I'm fairly sure not many put type of fuel used in a C&L. My 3 nothing mentioned, 2 issued by DAR's and the third FAA.
 
RV7A Flyer said:
First of all, there's nothing IN my Operating *Limitations* document that specifies anything about the fuel type. The only thing it says is that labels on the aircraft have to be correct.

Unless your OpsLIMS say something different, just change the label if you need to. It's correct now, changing it to read "100" instead of "100LL" it would still be correct.

Jeez....

ETA: from the post that YOU linked to:

(Emphasis added)
Click to expand...

Sure there is,

the most current ops lims

13. This aircraft must contain the placards or markings, as required by FAR 91.9. In addition, the placards and markings must be inspected for legibility and clarity, and the associated systems inspected for easy access and operation, to ensure they function as intended by the amateur builder/owner during each condition inspection.

So, whatever you did to comply with the above with placards and assuming an operating manual needs to be compatible with what ever you are fueling with.

If you specified “Unicorn Dust” as fuel then that’s what you have to use.

Again if you put LL for lead in your ops manual and corresponding placards then you painted yourself in a corner.

Whether or not this paperwork faux pas takes you back to phase 1 I’m not sure. But what I do know is that your stuff needs to match so you’re in compliance with your ops lims. No your ops lims don’t say 100LL they say you need to comply with 91.9. If you’re not doing that then you’re not complying with ops lims and you’re not airworthy.

Loose parts are bad, but bad paperwork also makes you unairworthy.
 
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N82VM said:
Sure there is,

the most current ops lims

13. This aircraft must contain the placards or markings, as required by FAR 91.9. In addition, the placards and markings must be inspected for legibility and clarity, and the associated systems inspected for easy access and operation, to ensure they function as intended by the amateur builder/owner during each condition inspection.

So, whatever you did to comply with the above with placards and assuming an operating manual needs to be compatible with what ever you are fueling with.

If you specified “Unicorn Dust” as fuel then that’s what you have to use.

Again if you put LL for lead in your ops manual and corresponding placards then you painted yourself in a corner.

Whether or not this paperwork faux pas takes you back to phase 1 I’m not sure. But what I do know is that your stuff needs to match so you’re in compliance with your ops lims. No your ops lims don’t say 100LL they say you need to comply with 91.9. If you’re not doing that then you’re not complying with ops lims and you’re not airworthy.

Loose parts are bad, but bad paperwork also makes you unairworthy.
Click to expand...

First of all, what "ops manual" are you talking about? There is no "Ops Manual" requirement for E-AB.

Second, even if I wrote a POH for my Experimental, I can update it any time I want. Same with my labels. Just change them. Not sure what the big deal is here.

If the point was "hey, your label by your fuel tank inlet says 100LL, and you're using 100UL, so you can't legally fly", ok, yeah. Whatever. Thanks for the tip, I'll change that label as soon as I get a chance. Meanwhile, here's a piece of masking tape, why don't you be a good fella and put a piece of it over the 'LL' so I'm legal. Thanks. Gotta run, got a flight to make...

Tempest in a teapot. When 100UL becomes locally available, I'll update my labels. And be done with it.
 
Also, don’t be so quick to blame if the aircraft owner is no longer the builder and had no say in what the ops limits stated when it was originally built.


N82VM said:
Sure there is,

the most current ops lims

13. This aircraft must contain the placards or markings, as required by FAR 91.9. In addition, the placards and markings must be inspected for legibility and clarity, and the associated systems inspected for easy access and operation, to ensure they function as intended by the amateur builder/owner during each condition inspection.

So, whatever you did to comply with the above with placards and assuming an operating manual needs to be compatible with what ever you are fueling with.

If you specified “Unicorn Dust” as fuel then that’s what you have to use.

Again if you put LL for lead in your ops manual and corresponding placards then you painted yourself in a corner.

Whether or not this paperwork faux pas takes you back to phase 1 I’m not sure. But what I do know is that your stuff needs to match so you’re in compliance with your ops lims. No your ops lims don’t say 100LL they say you need to comply with 91.9. If you’re not doing that then you’re not complying with ops lims and you’re not airworthy.

Loose parts are bad, but bad paperwork also makes you unairworthy.
Click to expand...
 
RV7A Flyer said:
First of all, what "ops manual" are you talking about? There is no "Ops Manual" requirement for E-AB.

Second, even if I wrote a POH for my Experimental, I can update it any time I want. Same with my labels. Just change them. Not sure what the big deal is here.

If the point was "hey, your label by your fuel tank inlet says 100LL, and you're using 100UL, so you can't legally fly", ok, yeah. Whatever. Thanks for the tip, I'll change that label as soon as I get a chance. Meanwhile, here's a piece of masking tape, why don't you be a good fella and put a piece of it over the 'LL' so I'm legal. Thanks. Gotta run, got a flight to make...

Tempest in a teapot. When 100UL becomes locally available, I'll update my labels. And be done with it.
Click to expand...

I said “whatever” you did to comply and assuming an ops manual. That can be whatever you did to comply with 91.9.

Yes you’ll need to up date it. I’m not sure if this is a “major change”. If it is a major change then you’ll need to do whatever it is that goes with that. I hypothesize if it were a major change it’s because your phase 1 was signed off with all the limits and placards at that time and the update now contradicts that. Again an exercise in paperwork.


Just trying to clarify what this actually means. There was previous mention in this thread about buying the STC. Just trying to keep bad gouge out of the conversation.
 
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