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John

Unleaded Avgas (94UL)

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Hi all,

 

There seems to be quite a bit of confusion about a new Avgas specification that is now available.  Many Airports and FBO's are now selling Unleaded Avgas (94UL Avgas).  This is a dream come true for anyone with a Rotax engine.  All the benefits of Avgas without the lead containment.  

 

Avgas is not Mogas.  Avgas is designed for aircraft, Mogas for cars.  We have been using Mogas as a compromise in order to avoid the high lead content contained in 100LL Avgas.  Avgas has a lower vapor pressure, a much better gum index and never contains ethanol.  Avgas is designed for a long storage life in our vented fuel tanks, while Mogas is designed for a sealed automobile fuel tank. Also, 94UL does not contain the offending blue or yellow dye that many of us have staining our wings.  Instead it is non-offending aromatic.  

 

An additional benefit for CT owners is that 94UL avgas will not turn the sight tubes yellow, or dark.  It will not gum up carbs like Mogas will.  And yes, you can still do 100hr oil changes with 94UL as it contains no lead.

 

I would urge all of you to purchase and use 94UL Avgas as much as possible for your benefit, and to encourage availability.  

Unleaded Avgas can now be found at the following airports, with more being added all the time:

 

https://swiftfuels.com/ul94-map/

 

On another note, one CT owner remarked that he is getting fuel leaks at his sump drain when using Avgas, this is because Avgas will not cause rubber seals to swell like Mogas will.  If this happens to you, this is an indicator that a seal or gasket may need to be replaced.

 

Happy Flying,

 

John

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"On another note, one CT owner remarked that he is getting fuel leaks at his sump drain when using Avgas, this is because Avgas will not cause rubber seals to swell like Mogas will.  If this happens to you, this is an indicator that a seal or gasket may need to be replaced."

 

Yes John that was me, Randy replaced the seal and all is good now, no leaks. Thanks for the advice.

 

Cheers

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Unfortunately, according to your map not a single airport in my state (Georgia) carries this fuel.  So as yet I have no choice but to continue using 93 octane mogas.

 

Good luck, I hope the availability of this fuel increases and the price decreases.  It's a great alternative for airplane engines that are not turbocharged.

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John, I've heard of possible valve problems with the Swift fuel (not in Rotax but in Lycoming engines)?  AIso wondering about the shrinking of the sump "O" ring - if this happens here, could other rubber components be affected?  My 2006 CTSW has lived happily with MoGas and Mobile 1  Racing 4T oil all these years. Flight Design owners are perhaps unique due to the CT's being built to accept alcohol fuel (except for the sight tubes!).  Buying 93 premium now in Michigan for $2.58/gal.  Just wondering what your thoughts are since you see overall affects on a lot of aircraft.   

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Hi All,

 

Glad to see so much interest in Unleaded Avgas.  

 

First, Unleaded Avgas does not cause "O" rings to shrink, it prevents them from swelling like the will with MoGas.

 

Yes, the cost is more, you will need to decide if the benefits for you outweigh the extra costs.  I can tell you that for me they do, for two reasons alone.

 

1. A fuel that will not "spoil" in a vented fuel tank and

2. No lead containment

 

Then add the other benefits:

 

3. Less service needed for carbs

4. No dye to stain wings

5. Sight gauges remain clear

6. Least possibility of vapor lock

 

During transition training, when asked what fuel is preferred I list them in this order:

 

1. Unleaded Avgas

2. Premium Mogas with no ethanol

3. 100LL Avgas

4. E10 Premium Mogas

 

The reason E10 is last on the list is the maintenance, vapor lock, phase separation, and other issues I have personally experienced with E10.  If you will burn it immediately, it may not be so bad.  The worse case is an older CT that has never seen ethanol.

 

I would recommed contacting your local airport or FBO about the possibility of carying Unleaded Avgas.  A great deal of Airports have sold MoGas, Unleaded Avgas is easier to sell as it is less difficult to store and insure.  Right now Swift Fuels is the distributor.  I do know that they will deliver to Georgia.  500 gallons is the minimum order.  You might even consider your own tank, as many others do.  Usually the regs for a 500 gallon or less tank are not so restrictive.

 

Best Regards,

 

John

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