Wings Forum

copilot 1 · Joined: 03 May 2007 Posts: 3 Location: SW Wisconsin

I have a new SLSA equipped with the 912ULS. This engine is one of the most unreliable I have ever owned. Temperatures below 45 degrees require preheat and then it is questionable. The Starter is not capable of cranking the engine without lockup as a result of the ignition system not providing for spark retard during the start cycle. The spark is always advanced. The result is the engine attempts to run backwards.

Due to "Rotax not being able to design a single point throttle cable system they leave the responsibility up to the aircraft designer to figure something out. The net result of this lack of engineering is evident in the reams of paper on how to balance the Bing carbrueators. Maintaining sync on any kind of a long term basis ( at least 5 or 10 hours ) doesen,t seem possible. To have this done by a mechanic is a 60 dollar job !! When the thing goes out of sync the vibration and noise level at any engine speed becomes obnoxious.

Parts costs are another issue. Failure of the antiquated ignition module is a $1200 bill and another $60/100 for installation !!

I wonder what the expirence of others is with this engine ?? And are there solutions ??

alan · Joined: 04 Feb 2005 Posts: 119 Location: Baytown, TX

copilot1,

I'm sorry to hear about your 912ULS problems. I have had none. My starter always spins the motor over briskly, every time. I live on the Texas gulf coast, so it is not often below 45 degrees, but we have flown when the temps are down in the 30's with no problem. I was under the impression that the ignition system varied the timing to suit the circumstanses. Are you sure about it "always being advanced"? If it is, it should be a warranty claim to fix it.

As to the throttle cables, I bought mine from Just Aircraft. It is a quality piece and keeps the carbs synched. I don't know if it would be legal to swap out any parts on a SLSA, so this info might not help.

We have 140 hours on our 912ULS and couldn't me happier, so far, knock on wood.

Alan

copilot 1 · Joined: 03 May 2007 Posts: 3 Location: SW Wisconsin

Alan----Thanks for the reply with your expierence with the 912.
Several points --Yes I have researched the ignition system. The timiing is fixed and no changes occur during operation. The firing point is always advanced. The modules are Ducati motorcycle ignitions modules.

I think I have a solution to the problem. One is a larger battery and the second is heavier cabling between battery and starter. I have also been tolt ptoblems will occur if the battery ages or the output for cranking falls off.

The throttle system is another issue which goes back to Rotax not providing a standart single point connection for the throttle. Also the system on my plane (Aerostar R40S) is a poor design for the throttle linkages from Aerostar.

I will look into your linkages and see how they could be adapted. As a further point of interest I have been told Rotax is going to make available a single point throttle system. This as a result of Cessna's expierence with the 91

Thanks again Milt K