Alternative Fuel Forum

[Marc_B]

MODERATOR:  What about a forum for Alternative Fuel Discussion and move all threads about alternative fuels there?  It'd be nice to see real world data for changes in fuel consumption, changes in engine monitor data, problems seen, pictures of before/after borescope/fuel leaks/etc.

[Brian2034]

Yes

My first question is why is there no STC available for mogas on the Mooney.

In my case the carburated 180 Mooney C

Avgas at the local FBO is almost $20 a gallon (Canadian dollars) as compared to $7 for premium mogas.

And no we are in one of the lucky regions where ethanol is NOT being used in the fuel.

Currently at the hangar there are a dozen aircraft running mogas and have been for years.  I'm guessing thousands of combined hours, with no issues.

[KSMooniac]

Mogas was shown not to work in Mooneys long ago, I believe, when all of those STC's were worked.

Sent from my motorola edge plus 2023 using Tapatalk

[Brian2034]

Do anyone know what models where tested?
Is there any information available on the testing or where to find the information?

 

[Marc_B]

https://www.autofuelstc.com/approved_engines_airfames.phtml

But I gather the issue isnt just that your engine can run it, but that the airframe and fuel system can as well. Hence an STC is needed for the airframe as well as the engine. 

[T. Peterson]

12 minutes ago, Marc_B said:

https://www.autofuelstc.com/approved_engines_airfames.phtml

But I gather the issue isnt just that your engine can run it, but that the airframe and fuel system can as well. Hence an STC is needed for the airframe as well as the engine. 

Do those STC’s mandate any physical alteration of the engine or airframe?

[Marc_B]

Why isn't the Mooney M-20-C or Piper Comanche approved?

The Mooney and Comanche both experienced vapor lock problems when they were tested. We solved the vapor lock problem but could not overcome pneumatic lock. Pneumatic lock takes place when the fuel boils as it enters the carburetor. The engine then dies due to an over rich mixture. This is just the opposite of a vapor lock where the engine quits or runs poorly due to a lean mixture. The better an airplane performs, the more difficult it is to get it through the flight test program.

[Marc_B]

46 minutes ago, T. Peterson said:

Do those STC’s mandate any physical alteration of the engine or airframe?

https://www.autofuelstc.com/stc_specs.phtml

Sounds like in some cases no. Depends on airframe. 

[Brian2034]

Lycoming has approved most of their engines for mogas.

But the airframe manufacturer hasn’t?

Is it that Mooney didn’t brother to look at their aircraft running on mogas or they didn’t want to invest in the work required?

Or do the mogas  STC’s originate from an outside source and and at the time their wasn’t  enough of a request for the STC  for mogas for the mooney models.

 

[Brian2034]

7 minutes ago, Marc_B said:

Why isn't the Mooney M-20-C or Piper Comanche approved?

The Mooney and Comanche both experienced vapor lock problems when they were tested. We solved the vapor lock problem but could not overcome pneumatic lock. Pneumatic lock takes place when the fuel boils as it enters the carburetor. The engine then dies due to an over rich mixture. This is just the opposite of a vapor lock where the engine quits or runs poorly due to a lean mixture. The better an airplane performs, the more difficult it is to get it through the flight test program.

Is there any documentation available from the testing.

From what I understand when performing testing for new STC for mogas they take the aircraft to extreme’s (air temperatures, altitude, etc)

 

[PT20J]

Perhaps is would be best to contact Petersen https://www.autofuelstc.com/

[Brian2034]

I sent an email to Peterson, no response as of yet.

The issue in our area is the price of avgas and it’s limited supply and also if and when an alternative fuel comes what the availability/ cost will be. (In our area)

With the aging Mooney fleet I’m guessing where not on the top of Petersen’s fuel STC list.
I also fly a Piper Warrior and the auto fuel STC for the warrior comes with the addition of a duel fuel pump setup. I’m guessing with the larger number of Piper aircraft they investigated further to provide a STC.

 

 

 

 

 

[jetdriven]

Not to mention that pretty much all of the gas in the US has alcohol blended in it and that's not allowed in Aircraft

[Brian2034]

23 minutes ago, jetdriven said:

Not to mention that pretty much all of the gas in the US has alcohol blended in it and that's not allowed in Aircraft

Not in our area!
And from what I understand not feasible for use in premium fuels in our area.

Apparently, ethanol blended fuel has a shelf life of 90 days and someone above my pay scale has determined premium fuels in our area won’t be consumed fast enough.