Aeroprakt fuel tanks compatilbility with ethanol fuel

[Mike Phillips]

Does anyone know if the fuel tanks on an Aeroprakt (A22 foxbat/A32 vixxen) are ok with using unleaded fuel with ethanol? What type of material are the tanks constructed of?

[pmccarthy]

I would not put ethanol anywhere near an aeroplane. But I don’t know the answer to your question, I do know that Rotax now allow up to 10% ethanol so it is a good question. They say refer back to the aeroplane manufacturer, and I have not done that for my A32.

Edited August 1, 2023 by pmccarthy

[Mike Phillips]

I only ask because Aeroprakt claims the fuel tanks are ethanol "resistant", which the earlier models apparently were not. But I'm unclear on exactly what "resistant" means. Not sure about Australia but in the U.S. unless you run unleaded auto gas the only alternative at most airports is 100LL which is very hard on a rotax engine & gearbox. More frequent oil & filter changes (ie every 25 hours) can mitigate the problem somewhat but not completely due to valve seat problems, spark plug problems and lead deposits in other engine areas. Thus, many people here run unleaded (which most areas only have this with ethanol) mogas of 91 octane or higher. So unless you want to run lead, most only have the option of using unleaded containing ethanol . Since ethanol can be destructive on certain types of plastic or fiberglass fuel tanks which is what Aeroprakt uses, this the reason for my question....

[kgwilson]

If everything is checked and found to be OK with ethanol I still wouldn't use it in an aircraft unless it is run virtually every day. Ethanol is hygroscopic and will absorb the moisture from the humidity in the air. Depending on the time of year and the level of humidity it will not be very long before there is water in the tank as while it is absorbed by the ethanol it will eventually separate out and being heavier than ethanol and petrol will end up at the bottom of the tank.

[skippydiesel]

I agree with all sentiment regarding NOT using ethanol blended fuels BUT your reasoning is a tad suspect.

 

Rotax approves the use of up to 10% ethanol/petrol (E10 )to a minimum of 95 RON.

 

The reason Rotax puts the onus on the aircraft manufacturer, to approve or not the use of E10, is that other components of the fuel system (tank, plumbing, pumps, etc) supplied by the manufacturer may not be ethanol resistant/proof.

 

E10 is in itself an acceptable fuel BUT has less energy per unit, than straight petrol of the same RON ie your engine, burning E10,  will not deliver quite as much power (likely impact on range more than noticeable power reduction).

 

Ethanol is hygroscopic but this is unlikely to have any significant impact on aircraft used frequently. The water content will remain in suspension and be processed by the engine in much the same way as an engine being flow in very high humidity/rain.

 

Aircraft that are not used frequently, often have more water in the fuel sample (pre flight draining) even without the use of E10, simply due to atmospheric water vapour condensing on the insides of the tank (if partially empty). In this situation E10 may produce more free water however if drained before flight should not pose a significant hazard.

[onetrack]

Ethanol destroys natural rubber and degrades fibreglass. If you have fibreglass tanks, it is highly advisable to ensure that no ethanol-supplemented fuel is used in them.

 

Skippydiesel is not quite correct with his opinion on water in ethanol. There's a nasty development called "phase separation" with ethanol-supplemented fuels, where the water comes out of suspension and causes problems.

 

https://www.leightonobrien.com/news/why-ethanol-early-fibreglass-tanks-dont-mix/

 

https://sutherlands.com/article/the-problem-with-ethanol-and-small-power-equipment/66

[Student Pilot]

I avoid any ethanol fuels in everything I have. If sitting unused for a month or two any carb bowls or sitting areas of fuel become sludged with a green slime. 

[spacesailor]

The ' ethanol ' destroyed my garden tool motors. 

Just blocked all the carby's by blocking the jets .

spacesailor