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Rotax STC conversion for a C150 / O-200, and overhaul costs


Some stuff from a UK distributor:

Shoreham EGKA, United Kingdom

This STC (and a few such converted airframes) have existed for 10 or 15 years. Looks crude and apparently is crude. A friend of mine instructs on one. Had an engine failure in it last year…

Even in Germany, where clubs and schools are so much into Mogas, fuel saving and noise reduction, this thing has never been a success. There will be reasons for that.

Mainz (EDFZ), Germany

I know a couple of schools that looked at this conversion in the past. And the simple fact was that overall the O-200 powered models were cheaper to operate.

This of course might change when Part M Lite comes into force as at present one of the main limiting factors was the Rotax TBO which is set at 2000 hours running time and not airborne time and no 10% plus 10% extension TBO is allowed.

The other development that might make it more cost effective is the fitting of the Garmin G5’s in place of vacuum driven AH/DI. The 912 can only drive a wobbly prop or a vacuum pump. Hence the fitting of the external venturi which I would regard as a retrograde step.

I would love to see this work so its great to see there is a UK distributor.

Last Edited by Bathman at 19 Dec 09:04

Can anyone give examples of actual issues found with the Rotax conversion?

Had an engine failure in it last year…

Well, anybody can get that; they happen all the time I had that in a Toyota/Lexus Soarer

Shoreham EGKA, United Kingdom

Two interesting factors mee the eye. As a former C150 owner, I see 18 kg more payload as a massive gain for an airplane which generally was very low on load. Mine was 513 kg empty and 726 kg MTOW so a mere 213 kg of payload, 150 kg with full fuel. 18 kg more would mean 168 kg of full fuel payload, which means 2x 84 kg instead of 2x 75.. ok, not the world but more realistic for todays people. Still would be a single seater for me however but as my flight surgeon tells me, thankfully they don’t come like me often.

Performance is similar: 90 kts TAS is the normal speed. However, 17 lph instead of 22 lph means that with the Rotax the 150 wins a full hour of flight time. Ok, lets see: 85.5 liters are usable fuel, @ 17 lph minus 45 mins reserve you get 4.15 flight time and roughly 380 NM range. With the O200, 85 liters will buy you 3 hours flight time (plus 45 mins Reserve) which at 90 kts translates to about 280 NM range.

So I’d see two big plusses for me: 18 Kg more payload and 100 NM more range. Plus Mogas of course. Also 90 kts seems tame, mine ran at around 95 at the time with a cruise prop.

Not bad at all….

LSZH, Switzerland

What is the price of this STC?

Novice pilot
EDVM Hildesheim, Germany

The only way fuel consumption will be improved is if the pilot doesn’t lean the O-200. With the Bing CV motorcycle carbs it partially leans itself, so with the Rotax leaning is not mandatory, but with the relatively peaky power curve a CS prop is necessary to make it climb. You trade one piloting duty for another.

The conversion strikes me as a bit silly.

Last Edited by Silvaire at 19 Dec 16:32

Mine was 513 kg empty

A typical microlight is 270-290 kg. LSA typically 300-350. VLA typically 350-450.

The only way fuel consumption will be improved is if the pilot doesn’t lean the O-200

Not when used for circuit work as a trainer.

but with the relatively peaky power curve a CS prop is necessary to make it climb

And the 150 climbs well with a O-200? We have fixed pitch on the WT9, and it tows gliders of 750 kg. Grantly it cruises at 95 KT at 5500 rpm with that prop while a normal WT9 cruises at 120 at 4800.


Never had any failure on O-200 during almost 900h within 11 years. Extremally simple and reliable engine.
Only about 5-7 hours on Rotax. On ground engine fire due to stupid rubber seal between carborator and engine block being ruptured due to vibrations.
Who puts two carborators on rubber seals just above the exhaust pipes??

Engine from snowmobiles adopted to aircrafts? No thanks.
Yes it burnes less fuel and the fuel is cheaper but the complication level and the quality of the connections, electrical cables – car style sockets and plugs.
For snowmobiles – yes. Even for jetski.


Raven wrote:

Engine from snowmobiles adopted to aircrafts? No thanks

I think that viewpoint has been argued before but the market has made a decision and does not agree with you; there are a LOT of new aircraft being sold with Rotax engines.

I would also comment that the snowmobile engine on an aircraft is a bit out of date. Maybe it started like that but it’s not a snowmobile engine any more, neither is a Thielert Diesel engine a Mercedes car engine nor a Williams FJ44 turbofan a cruise missile engine

Last Edited by Neil at 20 Dec 21:06
Darley Moor, Gamston (UK)
112 Posts
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