Rotax 912 Avgas

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JeffB

Filing Flight Plan
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Feb 25, 2018
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JeffB
I know that there is info on the web about using avgas part time in the rotax, and changing oil every 25 hours etc. But since there is NO mogas available at any Southern California airports, the FBO's block new companies from moving in and selling it, and big aiports suchs as KSNA, KLGB, etc. ban pilots from bringing their own fuel onto the field, there is no choice but to use 100% avgas. Does anyone have advice as to the long term effects of using 100LL 100% of the time (with or without Decalin) on rotax 912's?
 
I'm guessing the answer is yes, but if not, you can search for answers at rotax-owner.com.
 
My 80HP Rotax has just gone over 5000 hours on nothing but routine maintenance. The first 4000 hours were done largely on mogas the last 1000 hours totally on Avgas.

Now its running on Avgas we change the oil every 50 hours rather than 100 hours. We also change the plugs a little more frequently. Not that there is anything really wrong with them but they are so cheap you may as well.

You also get a bit of lead sludge in the remote oil tank and that needs cleaning out every once in a blue moon.

Its a great engine and I would choose one over a continental or lycoming any day of the week. When it gets to 6000 hours we intend on replacing it with a brand new factory unit.
 
Thanks for the info. There are lots of rotax LSA in Southern California (many even at KSNA), so I guess people are just dealing with the frequent oil changes and using Avgas.
 
I haven't inquired recently, but General Aviation at KFUL used to have MOGAS out of the back of the crew car (they put in a tank in the back of the Jeep Grand Cherokee that held something like 30 gallons I think). I have a hangar there, so I can fill my gas cans with MOGAS nearby and add to my plane, but I just use 100LL for convenience and to avoid vapor lock (since almost all MOGAS in SoCal has ethanol.)
 
I don't think the FBOs block anything. Our Chevron jobber included a $100,000,000 liability policy and was very strict on 100LL handling, testing, and QC end-to-end. I can't see how they'd want that liability for the few bucks mogas represents. The odds of one idiot running it in their Bonanza, crashing, and then suddenly needing all of that money to feel better about his choices is just too high.
 
Maybe it's an insurance issue like you said. It's just frustrating that after so many years of LSA and Rotax it's still virtually impossible to get mogas on field. I had a CTLS for a year and just got sick of trying to sneak 5 gallon tanks onto the field and then lug them up onto the wing etc. Moved back to Diamond/Cirrus and fueling went back to being a non issue. Anyway, enough ranting. Thanks again for all the info.
 
JeffB said:
Maybe it's an insurance issue like you said. It's just frustrating that after so many years of LSA and Rotax it's still virtually impossible to get mogas on field. I had a CTLS for a year and just got sick of trying to sneak 5 gallon tanks onto the field and then lug them up onto the wing etc. Moved back to Diamond/Cirrus and fueling went back to being a non issue. Anyway, enough ranting. Thanks again for all the info.
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Depends where you are ... last time I counted , I have 4 airports within 50 miles radius , 3 with UL 94 on the field and 1 with Mogas 91. On top of that nobody seems to give a crap if I haul Mogas to the hangar ..
 
Warmi said:
Depends where you are ... last time I counted , I have 4 airports within 50 miles radius , 3 with UL 94 on the field and 1 with Mogas 91. On top of that nobody seems to give a crap if I haul Mogas to the hangar ..
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Where is this wonderland of which you write?
 
Chicago south side suburbs , very close to Indiana which just happen to host the company behind UL94 fuels.
 
Bathman said:
My 80HP Rotax has just gone over 5000 hours on nothing but routine maintenance. The first 4000 hours were done largely on mogas the last 1000 hours totally on Avgas.

Now its running on Avgas we change the oil every 50 hours rather than 100 hours. We also change the plugs a little more frequently. Not that there is anything really wrong with them but they are so cheap you may as well.

You also get a bit of lead sludge in the remote oil tank and that needs cleaning out every once in a blue moon.

Its a great engine and I would choose one over a continental or lycoming any day of the week. When it gets to 6000 hours we intend on replacing it with a brand new factory unit.
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Wow, that’s seriously impressive! I have about 300 hours behind the 914 and I absolutely love that engine. The majority of my time is behind the 912 ULS though.

My Dad had a fuel tank put in the back of his F-250 and hauled 91 no octane all around but has since sold that truck and the airplane. When he didn’t have the truck he would haul the fuel with 5 gallon no spill cans.

Also, my former flight school used to run 93E10 but had issues with vapor lock so are now exclusively on 100LL with a fleet of about 16 912’s. Sounds like the 25 hour oil changes are even extremely conservative as the mechanics aren’t finding much sledge in the remote mounted oil tank.
 
Andrew Morris said:
Wow, that’s seriously impressive! I have about 300 hours behind the 914 and I absolutely love that engine. The majority of my time is behind the 912 ULS though.

My Dad had a fuel tank put in the back of his F-250 and hauled 91 no octane all around but has since sold that truck and the airplane. When he didn’t have the truck he would haul the fuel with 5 gallon no spill cans.

Also, my former flight school used to run 93E10 but had issues with vapor lock so are now exclusively on 100LL with a fleet of about 16 912’s. Sounds like the 25 hour oil changes are even extremely conservative as the mechanics aren’t finding much sledge in the remote mounted oil tank.
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I do believe that Rotax came up with a cure for the vapor lock issue, which requires a return line rather than a dead-headed system.
 
There’s a flight school in Lock Haven, PA that has been running several ROTAX 912’s on nothing but avgas with no problems they can associate with that fact.

As an aside, the owner does not run Decalin, which some do - it allegedly holds lead in suspension better, allowing it to pass through the system more readily. He’s of the opinion that when he did use it, it caused lead buildups in the exhaust system, which led to cracks in the exhaust.

I could ask him for details/clarification if anyone’s interested.

I personally run ethanol-free mogas almost exclusively. But I don’t worry about running avgas on cross countries, and I try to use Decalin when I do. And, anecdotally, I have had one exhaust crack in about 600 hours.
 
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I run my 912ULS and Rotax 912iS on 91-E10 autogas about 90% of the time. I haul it from the pump to the hangar in six 2.5-gallon No-Spill jugs. I fill up with avgas on XC. I change the oil at 50 hours, regardless. Never had any issues.
 
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