There?s no difference between theory and practice.
In practice there is. (Yogi Berra)
With that out of the way I will share with you my personal experience with the 912S engines and Jabiru engines we fly in our Titan Tornado exp airplanes.
We have four 912S and 2 Jabiru 2200 powered planes in my area. My 912S Tornado just went over the 500 Hour mark with nothing but oil and spark plug changes. It does not use oil and looks as clean as the day it came out of the box. It uses Honda motorcycle oil, NGK auto plugs, and auto gas (100LL in x-country mode)
We have almost 3000 hours of total time accumulated in the four 912S engines in my area, all of them trouble free with only the aforementioned maintenance and the routine carb synch job needed with the dual carb set-up. That?s basically 3000 hours of $0 spent on failed parts operating 4 engines (some of us upgraded to a new hi-torque starter that came form the 80HP legacy so we spent some dough on upgrades).
I know of two operators that reached the earlier 1000 TBO in the 80HP version and Lockwood found them in good shape and declared them fit to continue flying without the need for new parts or machining work. That?s the sort of experience that pushed the TBO to the 1500 mark it currently has.
The two Jabiru airplanes had their share of issues. One is an early model and had the heads warp once due to heat stress and had to be resurfaced. One a different flight, one of the distributor shafts (Honda car part) galled away causing one side of the ignition to fail.
The other jabiru engine is about two years old and has failed twice in flight, the first one resulting in the aircraft destruction. The second one was a lubrication issue that gave the pilot enough time to make it back down safely and save the airplane (second one due to an improperly installed oil seal). The dealer took the engine with less than 150 hours on the clock back and replaced it with a new one.
It is noteworthy to say that both Jabiru engine owners experienced carb ice in moderate weather conditions, specially at idle during final or whilst taxing. Carb-DeIce is a must if you are going to use the Jabiru engine. Some guys are using electric heathers around the carb intake to alleviate the problem.
While many seem to complain over the liquid cooled engine, they do not realize the benefits that the 912S has over other non certificated engines:
1. Parts and EXPERT Service is available throughout the country
2. It has a certificated cousin in the lineage
3. Virtually carb-ice fool-proof
4. No Mixture adjustments needed
5. Free, SAFE, easy to get cabin heat
6. Constant temps, no shock cooling
7. Modern engine construction with close tolerances
8. Owner support through the Rotax owner website publishing SB?s and AD?s
9. Comprehensive repair manuals are available
10. Thousands of hours of operation experience
11. Gear box allows for less stress on the engine and deliver equal torque to the prop
12. Able to use composite propellers from many vendors
13. Able to use constant speed and in-flight variable pitch propellers
14. Vacuum pump and aux generator available
15. Thousands of engines flying world wide
16. Starts easily in the winter time here in Wisconsin (NO PREHEAT NEEDED)
17. Able to use synthetic oils
I personally think that Van?s decision on going the 912S route is a good one, especially with those of us that are familiar with the engine and have hundreds of hours operating one and realize how good an engine it is. On the other hand, that choice may not go very well with those GA pilots that seem to trust only Lycs and Conts and dismiss the Rotax/Jabiru/<name your engine here> brands.
I just completed a 1300 mile x-country trip in my 912S Tornado. It cruised at 100K sipping 5GPH and never had to monkey around with carb mix, worry about carb ice or add oil in the almost 14 hours I spent away from home. Heck, It has 50 hours since my last oil change and the oil level is right where it was 50 hours ago! It starts instantly and the temps remain constant all the times. Overall, I know at least 20 Rotax 912S owners and their experiences are similar to mine with only routine maintenance performed.
The grapevine tells the Jabiru 2200 has their teething problems fixed and is becoming a very reliable powerplant. Problem is you still have an engine that is air-cooled, needs pre-heat, suffers carb-ice, revs at too high-rpm, is limited to short wooden props, has only 2 service centers in the country and has virtually no factory support for SB?s and ADs.
While I am not crazy about the RV12 design (bland, uninspiring, and too Zenith/<insert Euro design name her> like looking), I think Van?s reputation alone will be worth a few hundred sales amongst those seeking an LSA airplane. The cost of fuel is making it more attractive now to use these 5GPH power plants and get more clock-time per dollar vs. miles per dollar, depending on whatever makes you click.
Spend a few a hours talking to Rotax 912 and 912S engine operators before you make a decision on whether a 912 engine is for you or not.
Jose Borja
Elk Mound, WI