Rotax 912 ULS Slipper Clutch Necessary?

[sandbagsteve]

I'm looking at buying a plane with a 912 ULS fitted that is nearly new. The seller has made the statement that the slipper clutch adds another couple of kilos, and isn't actually necessary (provided you don't ding the prop into the deck!) for the purpose of normal starting/running/shutdown.

I learned on a C42 with a 912 ULS and slipper, and without the soft start it was still a pig to start at times (which eventually killed the slipper clutch), so I'm anxious that a 912 ULS without the slipper would be even worse to start?

My understanding is that all 912 ULS engines come with at least a basic torsional damper fitted (not a slipper clutch) to help smooth out the engine pulses transmitted to the prop.

So, does anyone have experience of the 912 ULS without the slipper?

And does the fitting on the soft start pack on an engine without the slipper still give the engine mounts an easier time?

Steve

[Monocock]

My a/c has a 912s with no slipper. It is correct that as long as you don't plan to ding the prop there is no problem.

I'm surprised that the C42 being difficult to start messed up the slipper clutch, I think you mean the sprag clutch.

As for the soft start module, there have been mixed successes with it and I would not suggest it is a guaranteed solution.

I have been operating my 912s for 6 months or so now and have found a starting and shut down procedure that works really well (very little kick back) and I would be happy to share it with you if you make the purchase.

The "s" 912 is a higher compression version of the 80 hp and therefore there is much less forgiveness at the start/shut down stage. Get it wrong and you can have a very "hard start" or vicious stop and there are various methods that can ease this.

All in all, the 912s is a superb engine and bombproof. I would highly recommend it and as for its performance, wait and see!!!!!!!!!!!!!!!!!!!

What a/c is it in?

[sandbagsteve]

Thanks Mono... We found that starting and stopping on one mag helped - and cold starts were always better with a booster battery connected. This example is in a skyranger - but we're still in the early stages of buying...

[letpmar]

Slipper

We operate a 912 ULS with a slipper clutch and have had one prop ding that sold mit for me. Starts seem fine and stopping on one mag after a short wait seems to help the engine stop a lot. If anyone else has another way of shutting down I would be happy to try it.

Pete

[Jan Olieslagers]

have had one prop ding that sold mit for me

Corresponding to what English phrase?

[patowalker]

It is cristal clear: "have had one prop strike, which justified the price of the slipper clutch" (it paid for itself, by avoiding the need for shock-load testing / stripdown and inspection of the engine)

[Jan Olieslagers]

You obviously have a different kind of crystal, over there,

[patowalker]

That's what happens when your brain is more used to another language.
I should have said "Más claro, echale agua".

[rans6andrew]

Rotax, themselves, clearly think that there is some merit in the slipper clutch, heavy duty starter motor and soft start as all are now standard on the 912s variants. This may mean that you need to have all three to get the effect.

Personally, I think that the key to it all is a good properly sized battery, short, heavy gauge leads and be sure to leave NOTHING drawing current when the aircraft is not in use. A battery isolation switch ensures that the battery stays as fresh as it can be.

Rans6.....

[patowalker]

Personally, I think that the key to it all is a good properly sized battery, short, heavy gauge leads

Exactly, but I don't think you need a battery isolation switch if you have a properly designed electrical installation.