What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

So Much to Learn about Rotax...

David-

Yes, .... The Rotax 912ULS has a slip clutch consisting of stacked plates very akin to a wet motorcycle clutch ... with the exception there is no mechanical release. The stacked plates are under constant pressure and designed to slip at a predetermined force to protect the crankshaft in the event of a prop strike.
 
Last edited:
David-

Yes, .... The Rotax 912ULS has a slip clutch consisting of stacked plates very akin to a wet motorcycle clutch ... with the exception there is no mechanical release. The stacked plates are under constant pressure and designed to slip at a predetermined force to protect the crankshaft in the event of a prop strike.
My understanding was that the slip clutch in 912 was an option whereas in the 914 or other higher models are standard. Of course I could well be wrong on this.
 
My understanding was that the slip clutch in 912 was an option whereas in the 914 or other higher models are standard. Of course I could well be wrong on this.

Depends on the model designation (and there are quite a few) of the 912.

On the ULS it is standard.
 
Scott,
Another subject....what fuel does the factory use in the RV-12?

We have a 100 Gal tank mounted on a small trailer that we keep in the corner of our hangar.

We purchase 91UL with 10% ethanol from a top tier brand station in the small town of aurora about 1 mile from the airport.

We have been using 91UL E10 in this manner for about 10 years now.

We have seen zero indication of ill effects with using the E10 fuel, but we use the fuel at a pretty rapid rate. I would guess that the fuel rarely sits in the tank for more than about 30 days. The exception to that is during the crumby weather winter months because we are flying much less. During that time we try and regulate how many gallons we put in the tank so that it wont site for to long.

We have quite a bit of experience with using 100LL as well. When we had RV-12's based on the east coast, they were operated on 100 LL and Decalin exclusively.

If using E10 fuel there are considerations to be made.
This previously issued Service Bulletin is a good starting point.
 
Thanks for reply.
I am moving to Minnesota, there are several local stations that sell 91 mogas without ethanol. That is the best option, or so it appears. The only thing that concerns me is 95F ops and vapor lock with this low pressure fuel system. A fuel injected system at 25-30 psi would be better.
But its probably all ok, there are many flying and have not heard of vapor lock with Rotax. There's some fuel pressure, may be just enough to keep things from boiling.




We have a 100 Gal tank mounted on a small trailer that we keep in the corner of our hangar.

We purchase 91UL with 10% ethanol from a top tier brand station in the small town of aurora about 1 mile from the airport.

We have been using 91UL E10 in this manner for about 10 years now.

We have seen zero indication of ill effects with using the E10 fuel, but we use the fuel at a pretty rapid rate. I would guess that the fuel rarely sits in the tank for more than about 30 days. The exception to that is during the crumby weather winter months because we are flying much less. During that time we try and regulate how many gallons we put in the tank so that it wont site for to long.

We have quite a bit of experience with using 100LL as well. When we had RV-12's based on the east coast, they were operated on 100 LL and Decalin exclusively.

If using E10 fuel there are considerations to be made.
This previously issued Service Bulletin is a good starting point.
 
Last edited:
Scott -

Does the factory demo RV-12 still have original vented fuel cap or has it been upgraded to the new fuel tank vent?

The reason I ask is that I believe the original vented cap is probably better to control air exchange in the fuel tank when aircraft is parked for extended periods of time.
 
Scott -

Does the factory demo RV-12 still have original vented fuel cap or has it been upgraded to the new fuel tank vent?

The reason I ask is that I believe the original vented cap is probably better to control air exchange in the fuel tank when aircraft is parked for extended periods of time.

If you mean the Red ULS demonstrator? It was the airplane that the the upgraded vent was system was developed on, so yes it has the upgraded vent system and undrilled cap. We have never had any operational issues with it.

It actually isn't part of the demo fleet anymore though. It has been reassigned to being a company flying club airplane, though so we are still able to keep up with monitoring condition as it continues to build hrs.
 
Back
Top