Actual Flying Rotax Installs

[Kai]

Casey,

Let me respectfully point out that there is suction at your lube oil pump hose barb oil inlet. In fact, the complete line from the oil tank to the pump inlet hose barb, is under suction. You need to make sure that the complete line is totally airtight. And pay special attention to the hoses in this cirquit. There have been cases where the hose wall has not been stiff enough to withstand suction, and consequently was sucked flat: exit some fine R912’s.

The external lube oil system works with crankcase pressure forcing the spent oil through our banjo and to the oil tank. The tank itself is vented and there is only ambient pressure in there. When replacing the oil in the tank we are supposed to do this with the aid of compressed air: do not exceed 1bar/15psi!, the manual says.

Then suction from the lube oil pump draws oil from the tank, through the cooler, and forces it into the oil galleries. Then back to the sump. Why the system designers in their infinitive wisdom decided that this was the salvation of mankind, is beyond me!

Remember : Murphy lives!

Thanks
Kai

[CaseyCooper]

Kai,
I agree completely. Perhaps we’re saying the same thing differently. The line coming from the can to the oil pump, below the gear box, is under suction. The line from the sump, to the can, is under pressure. Like you said, crank case pressure.
But I agree with the compressed air. It’s important to prime the pump after an oil change, especially for first oil add when new, with a dry/partially dry pump.
However, your oil cooler should not be between the sump and can. It should be between can and oil pump. Reason being, if you cool the oil substantially before it reaches the can, the heated water in the oil system does not vapor off and go out the vent. It should go in the can hot, through the cooler, and back through engine cool, so we can get rid of that junk.
But I agree! I actually know a guy this happened to, he panicked and crashed his plane because he lost oil pressure, and instead of just flying the plane to a safer area and maybe toasting the engine, he put the plane down in a terrible spot and destroyed the plane. Sometimes panic just gets the better of you in those situations

[Kai]

Casey,

Yes- and regarding the isolators I’m still very interested to see what Sonex comes up with. You will publish on these pages?

Panic should not be taken lightly. My former Jab engine had an electrical fire (shorted charging lines from alternator to rectifier) at 2700’ agl. The first thing I knew was that the oil pressure went to zero (shorted after insulation on lead from sender to gage melted). Then that acrid smell in the cockpit and gradually so full of smoke I could hardly see out. I was convinced I had a fuel leak and would go kaboom shortly. Switches off, fuel off: one smoking glider with poor specs.

I won’t say I panicked, but I became VERY focused on getting the thing back on terra firma.

This was in ‘12. Kerry Fores got the news just after he was back from his summer vacation- he flatly stated he refused to go on any more vacations if I/we insisted to carry on with these sort of things. Took me thirteen months and huge plywood box with airframe parts from Sonex to get #0525 back in the air again.

Try to avoid this yourself- I most certainly hated it. Install the R912 according to the book and operate it accordingly.

Thanks
Kai

[SonexN76ET]

Here is how Rotax specifies how the oil circuit is to be configured. From what I understand Herraripower is compliant with this configuration. I agree with Kai, however, that the oil hoses and fittings must be of top concern. I originally made my own oil lines with AN fittings but before first engine run learned more about the nuances of the suction technology Rotax was using and decided to order custom Teflon aircraft hoses with AN fittings from Aircraft Specialty that are designed for the suction used by Rotax engines. The oil lines were expensive however. $600

Jake

[SonexN76ET]

While looking at images of other Rotax 912 engine mounts I came across these on the internet on a Titan Tornado with a 912. It looks similar to Herraripower’s design but with the angles turned outside instead of inside.

Jake

[CaseyCooper]

Kai,
I will absolutely! I want to make sure everyone is safe here. And if anyone can learn from something someone has encountered, that’s a good day! Keeps everyone from learning the hard way.
Yikes! I’m glad you made it down though. It’s most important that you were able to walk away and add it to your life’s adventures hopefully to never happen again! Sometimes planes can be your friend, sometimes they’re moody.

Jake,
Fittings and clamps are very important items to set properly! An is definitely the best way to go. The Teflon hoses are basically “forever” hoses, but everything has a lifespan. When installing any hoses you have to be sure of their max suction and pressure ratings. My 912 is not the newest, but the banjo/barb at the sump is factory, and barb fitting at the pump as well. Very common on the older models and have always worked. However, your setup is gorgeous, I was looking at it in your pictures, and definitely the ideal way to go. When my condition of my hoses are up, going that route is very enticing.
Those are on a titan? Those are mounts for a Rans s12! Maybe they use the same mounts? I haven’t seen a Titan out my way with a 912. Or many Tornados at all for that matter. That’s where I took my idea from. We have an s12 in the shop right now next to my Sonex so I just looked at it and reimagined the wheel. I mean it isn’t that hard of an idea to come up with, and like Kai said before, it’s not our idea or a new one. Just seemed like something that would work. But that’s exactly where I got it from. That’s where I got the thicknesses, bushing type, etc.

I did talk to Mark yesterday and he’s working with John on ideas. They’re working very hard and staying focused. Sonex does a great job and I think we’ll be reaching a solution soon.

[Zack]

I did talk to Mark yesterday and he’s working with John on ideas. They’re working very hard and staying focused. Sonex does a great job and I think we’ll be reaching a solution soon.

Thank you for keeping us posted! Please let Sonex know there are other builders waiting for this to be resolved. I just received my engine yesterday. I haven't called Sonex yet because I figure a minute they spend on the phone with me is a minute they are not working on a solution :)

[SonexN76ET]

Here is some more food for thought on engine mounts. Here is the engine mount on a SeaRey Amphibian



I am wondering if a similar setup could be used with the Sonex engine mount?

Jake

[Zack]

This is what Thomas from Edge Performance in Norway is using. It's his personal mount and not a product that he offers. I like how it uses the Rotax ring mount design versus a bed mount.

Edit: This isn't completely accurate, please see Kai's message below.

[Kai]

Jake,

Almost anything is possible!

My guess is Sonex will try to aim for a solution where the welded truss can still be used in its existing form, without having to undergo some form of change. In this way only the brackets will have to be replaced with something more suitable, for instance something along the lines Casey has already shown. However, this is pure speculation from me.

Previously it was pointed out that the isolators needed to be loaded axially. The design that Rotax employs with the ring mount was also mentioned as a proper example. However, is this an absolute fact? True, when the isolators in this design are torqued to specs, they compress axially, but what then? At least as long as the engine is not running with the prop pulling, there is no further axial load. On the contrary, engine weight will then at least partially impose a radial load on the isolators. This will over time cause them to deform, just as they do on Jab engines, where I have repleced dozens of them, notwithstanding the fact that there is a 3/4’’ steel tube in their center to support them.

Would it not be better to have the isolator totally encased in a steel housing like on the dynafocal mounts? As mentioned earlier, something like this could be attained by tightening up hefty hose clamps around them. Then again, when would such measures finally be sufficient? Talk about over engineering something!

Thanks
Kai