Would we need a STC for unleaded fuel?

[EricJ]

3 hours ago, GeeBee said:

If you read the TCDS for the engine, you will likely find other approved fuels other than ASTM specifications. For the IO-550 that is absolutely true. For Lycoming, not so much.

The Lycoming TCDS also provides for multiple international fuel specifications, as I've mentioned previously.   You need to look more closely at the Lycoming TCDS. 

Also as previously mentioned, for an engine installed in a certificated airframe the airframe TCDS drives, so we really only need to look at the Mooney TCDS, as initially asked by the OP.   It is still true that "minimum grade aviation gasoline" means that a grade equal to or higher than that specified in the airframe TCDS can be used according to that TCDS.   So 115/145 can be used even though it is not specifically identified in the TCDS.   If another fuel comes out that meets "minimum grade aviation gasoline", it *can* be used without STC since it meets the TCDS.

 

[GeeBee]

The reason why I said "Lycoming, not so much" is it is true that the Lycoming TCDS refers to SI 1070 the latest version I believe is 1070AB. If you look for instance at the IO-360 it is true that some versions can run several international standards, but some versions no. Namely -J and -K which are limited to the ASTM and DEF-STAN (which for all practical purposes is ASTM) standard. GOST and TU standards are not approved.

As to airframe limitations that is also true because not every airframe has the same sealants, seals and hoses. Some AFMs say fuel that meets the engine TCDS. Others like Mooney are more specific and I suspect that is due to the sealants in the wet wing.

The reality is, and I've been to some pretty backwards places like Kyrgyzstan, which is part of the old Soviet Union and not even GOST standard is available (even though Kyrgyzstan adheres to GOST standards for the most part). It is all ASTM. I think your likelihood of finding these "other international standards" fuel is almost nil because the production level is so small it is easier to import ASTM fuel in barrels. So if you are running a piston engine airplane requiring 100 octane aviation grade fuel, it is ASTM,  or bust.

[Hank]

4 hours ago, GeeBee said:

So if you are running a piston engine airplane requiring 100 octane aviation grade fuel, it is ASTM,  or bust.

Or Gami . . . .

[GeeBee]

25 minutes ago, Hank said:

Or Gami . . . .

With an STC

[carusoam]

Sooooo…..

For comparison…

There is a common fuel STC for many planes to allow the use of car fuels…

I believe it may be owned by EAA or a similar body…

It basically gets sold for the price of handling the paperwork and decal…

 

There are plenty of people and organizations that would like to do away with the lead…

The cost of the STC may be a drop in the bucket….

 

Lets not get too excited… until we see the numbers… and their ability to actually supply fuel…

 

If the government mandates it… let’s get excited immediately… do not wait!  this would be a supply disaster in the making…  AOPA would be all over it…

 

PP thoughts only, not a fuel lawyer…

Best regards,

-a-

 

[1980Mooney]

Get ready to pay for your STC....

 

[1964-M20E]

y'all STC folks don't go gett'n you panties in a wad