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How Can I Use Unleaded Avgas?

ArVeeNiner

Well Known Member
Well, my home airport (KRHV) is again under attack for closure. This time, they are going after the leaded gas. The good news is, they are now selling unleaded avgas at the airport. I want to do my part and use it in my RV as much as I can.

I am running an O-320 B2B in my RV. Can I just start using it since it's an Experimental or are there some hoops I need to jump through?
 
If you have not upgraded the pistons , there is an octane rating you need to hit, otherwise u have nothing to do. I run 92 octane UL in my O320 160 hp 8:5.1 d1a no issues.

O-320-B, -D (except –B2D, -B2E, -D2J) ..................................... 91/96 or 100/130 octane, minimum
 
Need way more info

Unleaded fuel covers a wide range of stuff. Lots of variables/parameters to consider:

Is the UL fuel MoGas or one of the aircraft alternative fuels?
What is the listed octane rating of the fuel/I.A.W. what standard?

If Mogas, what is your fuel system config? Standard fuel driven pump and boost?

etc.

It's not just as engine consideration.
 
UL94 per AirNav. If I believe the marketing on the Swift website it is 100LL without lead. So it should meet RVP needs of GA. It's better than mogas.

I would have no issues using it in my 7 with equal or less price, then using 100LL anywhere UL94 is not available. Since all but octane is the same (IF) then boost pump procedures should be the same. I have a M1B with 8.5:1 and Lycoming approved for mogas. My 7 fuel system would give me pause in the summer related to vapor pressure, but not UL94.
 
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IO320-d1a yes

I have a IO-320-D1A as sold from Vans and it is approved for unleaded avgas use. I think the only unleaded avgas that is avialable now is the swift 94UL
 
I dug around the Swift website and punched in the type aircraft my engine original flew in (Piper PA-28) and got this:

Ready To Fly!

Congratulations! This aircraft is FAA-APPROVED TO FLY on UL94 Unleaded Avgas!

This aircraft can use UL94 Unleaded Avgas based upon any of the following criteria:

UL94 Unleaded Avgas meets or exceeds the FAA's type-certificated fuel requirements of both this engine and airframe. The TCDS fuel requirement for both engine and airframe states one of the following: Grade UL91, Grade 80, Grade 80/87, or a minimum octane requirement of 80 or lower.

UL94 Unleaded Avgas complies with the requirements for Grade 80 unleaded avgas (as originally specified in ASTM D910). Grade 80 was last approved as an unleaded grade of avgas in 1995, per D910-95A.

UL94 Unleaded Avgas also complies with the requirements for Grade UL91 unleaded avgas as specified in ASTM D7547.


So I guess that part of the question is good. As far as paperwork I would guess I don't need anything. Is that correct?
 
Not sure what you mean by "unleaded avgas". The definitions are confusing, and not entirely uniform.

Lycoming has approved the O-320 B series for a variety of unleaded fuels (see below). If you read Lycoming's articles on aviation fuel parts 1, 2, and 3, you'll get a better background but note that they make a clear distinction between pump gas, mogas, and unleaded aviation fuels, basing most of that on demonstrated "airworthiness". In the meantime, you could review SI1070AB, maybe see where the fuel your airport sells falls on Lycoming's chart

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Lycoming has a document that says what fuel we can use in our Lycoming powered airplanes. There are 3 articles that also talk about unleaded fuel. 1 2 3

For the most part, Lycoming approves the use of a lot of alcohol free mogas with a 93 AKI or higher rating for most of the parallel valve engines we use in our RVs.

Without knowing more, most likely the unleaded fuel sold at the airport would be ok with a 160 HP Lycoming or clone engine we use in our RV aircraft as long as it is 93 octane or greater.
 
So I guess that part of the question is good. As far as paperwork I would guess I don't need anything. Is that correct?

You are correct Kelly - your airplane is experimental - legally, you can run moonshine if you want! All sorts of posts (above) on the engineering, but from a paperwork standard, you can run what you want.

Paul
 
Moonshine??? Hmmmm...that would be unleaded too and maybe cheaper! You're a genius Paul. Now excuse me while I order myself some flasks! :)
 
You are correct Kelly - your airplane is experimental - legally, you can run moonshine if you want! All sorts of posts (above) on the engineering, but from a paperwork standard, you can run what you want.

Paul

And Paul, to add a bit of levity ...

Where I am from (Deep South), growing up, the old-timers would say "Jest make sure it's **High Test**" !!

Most people here are probably too young to know the meaning.

Now, in response to the O-320 B2B, we ran premium auto fuel (no ethanol) in our plane 10 years ago as a test and had no problems.
 
The only problem that might arise is if not using self service, the line-boy might refuse to fill with 94UL if your fuel caps are placarded 100LL only.

I've been cautioning people for years not to put 100LL on their fuel caps. Only put the minimum octane rating. Lead content has never been a requirement on the placard.

When 100LL goes away, there's going to be a multitude of obsolete fuel caps out there. Maybe engraving fuel caps is in my future!
 
The only problem that might arise is if not using self service, the line-boy might refuse to fill with 94UL if your fuel caps are placarded 100LL only.

I've been cautioning people for years not to put 100LL on their fuel caps. Only put the minimum octane rating. Lead content has never been a requirement on the placard.

When 100LL goes away, there's going to be a multitude of obsolete fuel caps out there. Maybe engraving fuel caps is in my future!

Good point Mel. I didn't think of that. I have stickers on mine but I don't remember if it calls out for 100LL or octane. If it does call out 100LL, I'll add more stickers.
 
The only problem that might arise is if not using self service, the line-boy might refuse to fill with 94UL if your fuel caps are placarded 100LL only.
No self-serve here but when they come down to my hangar to fuel me up, I always take the caps off myself.

I'd like to run one of the unleaded fuels on Lycoming's list in my IO-320, but until they put some on the truck, I'm pretty much stuck with the 100LL.
 
I wish we had an unleaded aviation fuel available at one of our local airports - best if it was at my home base but any of the four local ones would be great.

While our Glasair Sportsman runs 100LL just fine and has 8.5:1 compression so will run UL94 with ease, our C85-powered Davis DA2A was designed to run on 80 octane - it hates 100LL. I'd be so happy to strike the middle ground with 94UL or similar.

BTW my last 100LL fill-up on the weekend cost $2.08/litre, plus 13% sales tax, for a total of about $2.35/litre. Now those are litres and Canuck bucks, so translated into 'Murican that comes out to about US$7.02/US gallon. That wasn't particularly expensive fuel, just the going rate in the area.

Yup, I sure wouldn't mind burnin' some corn squeezin's in my airplanes. No problem with octane but ethanol's about 10-15% less energetic per unit of volume. Still, I'd happily sacrifice some range to kick the "dead dinosaur" habit.

Or, just send up a truckload of that UL94, please and thank you! :D
 
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