Auto Fuel in Grumman AA1/AA5?

N

nikos1

Filing Flight Plan
Joined
Aug 3, 2024
Messages
5
Display Name
Display name:
Niko
Hey everyone!
This is my first post, I am considering buying a Grumman AA5 or an AA1 to time build in with a friend. Does anyone know if these aircraft with their standard Lycoming O-320-E2G (AA5) and Lycoming O-235-C2C (AA1) are able to use unleaded fuel? Is there a way I can check to see if they are approved? I went on this website to check, but I was going to ask everyone here to see. That website confused me a little bit.
Any information helps! Thanks!
 


Petersen Aviation | Auto Fuel STC

See if an Auto Fuel STC is available for your airplane. Auto Fuel STCs are approved on 48 different engine types and 100+ airframes including nearly all 80/87 octane engines and the majority of airplanes in which these engines were installed.
www.autofuelstc.com

If one of those two has the engine / airframe combination listed, you can buy the STC. If not, then not.
 
There is only little mystery with the Petersen Autofuel STC. The AA5 airframe is on the list, the AA1 is not.
The big caveat here: the fuel must be ethanol free. So you cannot pump whatever you get at the next street corner for 2.99$/gal. And from time to time there are airports that do not allow that you bring your own fuel.
 
aggiepack said:
There is only little mystery with the Petersen Autofuel STC. The AA5 airframe is on the list, the AA1 is not.
Click to expand...
EAA lists it. Petersen probably didn't find one to test. I asked them about Navions years ago (for the lower compression versions). They said they tried it and it failed, but they couldn't tell me which engine, carburetor, etc... they'd actually tried it on. Even from the factory Navions came with E-185, E-225, various IO-470's, and the GO-435. On the carbed versions, there were a variety of carburetors available (this is for example the difference between a Navion and Navion A).
 
StraightnLevel said:
Your question is a bit unclear. You asked if it can run “unleaded fuel”.

Are you asking if it can run unleaded avgas like UL94 or G100UL, or are you asking about running automotive gasoline?
Click to expand...
Automotive gasoline, or other gas if it is possible but I haven't done enough research to know about running other fuels but I would assume they wouldn't be compatible? But yes my question was a little unclear, I meant to say automotive.
 
StraightnLevel said:
Out of curiosity, why?

Nearly every airport in the US that has fuel service has 100LL available. In fact, I would suggest that it's far more available than ethanol-free automotive gas (unless there is some reason that you have access to ethanol-free gasoline).

How would you get automotive gas to the airport to fuel your plane?
Click to expand...
I have never owned an airplane, nor have I had to buy gas for one. I am finishing up flight school and about to buy an airplane to time build in and from what I have heard you save money not having to pay for $6 to the gallon on 100LL. If we are time building, then gas will be a huge expense in the long run.
 
StraightnLevel said:
Out of curiosity, why?

Nearly every airport in the US that has fuel service has 100LL available. In fact, I would suggest that it's far more available than ethanol-free automotive gas (unless there is some reason that you have access to ethanol-free gasoline).

How would you get automotive gas to the airport to fuel your plane?
Click to expand...
Cost, for one thing. Lack of lead fouling , for another.

I ran auto gas some of the time in my T-Craft, brought it in a 5 gallon jug. My BIL has a backyard strip for his RV-8 with a 250 gallon mogas tank by the hanger, fuel delivered by truck.
 
I had an AA5 Traveler in the 90's. We primarily ran 87 UL autogas in it, with no problems whatsoever.
As others mentioned, it is now more difficult to find ethanol-free autogas.
Jon
 
nikos1 said:
from what I have heard you save money not having to pay for $6 to the gallon on 100LL.
Click to expand...
As others have mentioned, the STC does not include E-10 (10% ethanol) which is found at most gas stations.

If your primary objective is time building, there are a lot of experimental amateur built aircraft with Rotax 912/914 engines that can run on E-10 all day long. (That's what I use.)
 
Yes, there are autofuel STCs available for both the AA-1X and AA-5/AA-5A, provided they have the stock, low-compression engines. I flew my AA-1A (O-235-C2C) and AA-5 (O-320-E2G) for many years on autogas STCs. (I believe my AA-5 had a Petersen STC.) Unfortunately, it is difficult to find conforming, ethanol-free autogas at local airports anymore. (That means transporting fuel, and conforming to you local airport's self-fueling policies.)

Many AA-5s now have high-compression STCs which limit them to 100LL or G100UL (via STC) operation. The high-compression engines are very desirable and are much better matches to the airframe. The HC STC for my AA-5 was well worth it, especially when combined with a higher pitch STC propeller.

You may discover that fuel is not the most expensive ongoing cost of operation. For most light singles, fuel costs are only about 25-35% of the cost of ownership. When traveling, you will likely find autofuel difficult to find and will wind up using 100LL anyway. This reality made it easier for me to pull the trigger on the HC STC during overhaul. I simply wasn't getting any practical use out of my autogas STC.
 
One AA-5 had HC pistons at o/h to upgrade hp to 159.

It also has the auto fuel STC .

Operated well for years.
 
Magman said:
One AA-5 had HC pistons at o/h to upgrade hp to 159.

It also has the auto fuel STC .

Operated well for years.
Click to expand...
The STC was probably voided with the installation of the pistons. STC's are usually for a specific airframe and engine model. By installing the HC pistons the engine model changed effectively becoming a -D or -H. Does it work, probably especially since most ethanol free gas is 91 octane but it is not legal unless a new STC was obtained/obtainable after the upgrade.
 
Magman said:
One AA-5 had HC pistons at o/h to upgrade hp to 159.

It also has the auto fuel STC .

Operated well for years.
Click to expand...
The Bill Scott HC STC specifically requires 100LL to be used for adequate detonation margins. The autofuel STC is null and void after the conversion.
 
You must log in or register to reply here.
Back
Top