There is the Peterson STC for “autofuels” but it does not define what “autofuel” is https://www.autofuelstc.com/stc_specs.phtml
In an email from them I was told – part of email below
Therefore the STC consists of a pair of redundant electric fuel pumps with revised plumbing. We removed as many 90 and 45 degree fittings as possible, and replaced them with gradual bends to stainless steel tubing. This cuts down on turbulence and makes vapor lock less likely. The pumps come to you as an assembly with the tubing already bent. Your mechanic tightens up the fittings, and then mounts it on the firewall in place of the original Piper installed pump, which is discarded. The hose to the inlet of the engine driven pump is replaced with a new hose. A fitting in the fuel selector is also changed out. Your IA then needs to install the switch and circuit breakers to control the pumps …………………………This then approves the airplane for 91(minimum) AKI automotive gasoline
He mentions vapour lock so presumably this means fuel with ethanol but also what worries me is that my EDM fuel flow flow monitor has an impeller so would this impeller create vapour lock?
On another subject can an 0-360 merely run on any of the Aviation grade unleaded (not mogas)?
Archer-181 wrote:
On another subject can an 0-360 merely run on any of the Aviation grade unleaded (not mogas)?
Depends on which unleaded avgas you mean, and what the compression ratio is of the o-360.
If you mean G100UL then yes, it will run fine, according to George Braly.
https://gami.com/g100ul/g100ul.php
If you have a reasonable compression ratio on your o-360, like less than 10:1, (most are 8.5:1) then you’ll probably be fine with UL91. I’d recommend doing some research for your particular airframe and engine to be sure which unleaded avgas will work.
I run 100LL, UL91, and BP premium non-ethanol mogas in my 8.5:1 IO-360 and it works great.
eurogaguest1980 wrote:
I’d recommend doing some research for your particular airframe and engine to be sure which unleaded avgas will work.
Lycoming (and probably also Continental) publishes detailed lists of what fuels their engines can accept. Reading that is all the research you need to do. There is no reason researching the airframe. Indeed, EASA gives blanket approval for use of unleaded AVGAS in all airframes which were originally certified for 100LL. (Provided, of course, that the engine can use it.)
Archer-181 wrote:
can an 0-360 merely run on any of the Aviation grade unleaded (not mogas)
Standard compression Lycoming 0-360 would run just fine on the cheapest mogas you can get, think the one from Tesco or whatever cheapest brand comes to mind
what you want to avoid is to
1. overheat the engine and oil
2. use winter mogas during summertime
Archer-181 wrote:
There is the Peterson STC for “autofuels” but it does not define what “autofuel” is
It does … by referencing to EN 228 ROZ 98 and ASTM D-439 / D-4814 and anti-knock index min 88 octane (ROZ+MOZ)/2 and explicitly saying ‘fuel from auto petrol pump’. Yes, they changed the norm, but the STC is still valid and does give a lengthy explanation with a lot of details to consider. There is a reason they are highly specific on the airframe and engine they approve for the STC. Even further, they are quite knowledgable on the fuels. I had a conversation after they put food in the fuel on which exact auto fuel is suitable and they checked data sheets to confirm which gasoline is compliant with their lab tests from the STC process.
Airborne_Again wrote:
Indeed, EASA gives blanket approval for use of unleaded AVGAS in all airframes which were originally certified for 100LL
If the airframe vendor does approve … often forgotten. The legal approval of EASA, whatever this means in the light of responsibilities of the aircraft operator, does have its quirks, as it frees engine shops and maintenance organisations from certain liability – ‘this fuel was not approved by the airframe manufacturer’ is not seldom heard nowadays and EASA won’t take accountability for any harm done by their legal approval.
EASA won’t take accountability for any harm done by their legal approval
It’s part of “risk-based approach” to regulation (the clue is in the name) and scores lot of points for “the agenda of decommissioning LL”…an airframe approved for LL Avgas will run on UL Avgas if engine is UL approved, it’s hard to generate data that state otherwise, it will be very hard to find one single counter example?
MichaLSA wrote:
If the airframe vendor does approve … often forgotten. The legal approval of EASA, whatever this means in the light of responsibilities of the aircraft operator, does have its quirks, as it frees engine shops and maintenance organisations from certain liability – ‘this fuel was not approved by the airframe manufacturer’ is not seldom heard nowadays and EASA won’t take accountability for any harm done by their legal approval.
There is no such requirement. Or if you believe it is, please point me to it as I would be very interested. Ref. Standard Changes CS-SC202c and CS-203c. None of them state that the airframe vendor needs to approve.
Airborne_Again wrote:
There is no such requirement. Or if you believe it is, please point me to it as I would be very interested. Ref. Standard Changes CS-SC202c and CS-203c. None of them state that the airframe vendor needs to approve.
Checked and yes, you are correct and I am wrong. Current Issue 4 of CS-STAN no longer mentions the the airframe clearance, which even means EASA approval may stand in contradiction to vendor SBs disallowing the use … o-O … looks not really thought to the end, but does not change things with regards to liability topics. Whom to sue when an engine shop denies warranty cases?
MichaLSA wrote:
Current Issue 4 of CS-STAN no longer mentions the the airframe clearance
CS-STAN has never mentioned airframe clearance (except for other kinds of AVGAS or MOGAS). The changes from the first version in 2015 were including AVGAS 80 among the kinds of fuel that the airframe must already be approved for and including some additional references to rules concerning Pilot-Owner maintenance.
The site to order the STC for G100UL is live: https://stc.g100ul.com/.
The cost for a TB20 with an IO-540 is $475 ($50 for the airframe and $425 for the engine).
The related documents like installation instructions are at a different site: https://gami.com/g100ul/downloads.php. It seems they send you a label to apply to the engine, and a 337 is needed because it is an STC.
That’s the theory 
