Thread: SL912-016

Has every one read the new service letter and figured out what it will mean to our CTs?

Also the suggestion for dynamic prop balance.

Paul
466CT

link to service letter: http://www.rotax-aircraft-engines.com/p ... d04645.pdf

When they say minimum 5200 RPM with WOT at take-off.... do they mean "at take-off" (like the moment of take-off), or "climb-out"... and if climb-out, at what angle/speed??? I'm pretty sure my normal climb-out after take-off is around 5,000. It seems re-pitching the prop to give me 5200 would result in a cruise WOT of something too high.

Tim

5200 RPM with WOT at take-off, to me means rpm on takeoff roll.

i would think this is a flat enough pitch to where you could not cruise at wot without exceeding 5,500, but i now think that is fine. if you do overspeed you can hear it.

this supports the contention that the motor was designed to run at 5,500rpm for its entire life.

it also supports that lower rpm cruising needs to be done at lower mp, in other words many have been flying in too high a gear

I never see 5200rpm on takeoff, maybe 5,000 but my field elevation is 3500 ft and DA of 5-6K everyday. I guess that would make a difference. As a matter of fact, I've never seen it above 5300rpm unless i'm descending a little bit and then it goes to 5350rpm which is the highest I've ever seen. Maybe I should have my prop checked? It only has 50hrs on it and that's the way it came from the factory.

John

John:

They often come too coarse from the factory. There is a ton of info on this here on previous threads. Sounds like your prop is too flat.


WF

Sounds like it has too much pitch. I pitched mine to get 5600 straight and level but I only get 4900 on TO guess I need to flatten it out some to comply with the SL.

I have revised my shutdown proceedure in response to this SB! I will now pull throttle ALL the way back, kill one side of the ignition, wait for the rpm to drop, then kill the other side! - WF

I'm not sure where they want you to hit 5200 RPM. As the roll starts, the RPMs drop slightly, probably with the prop being able to "bite" the air now that it's moving forward and not just creating tons of turbulence, and then comes up after 15 kt or so. It's a slight effect, maybe only a few hundred RPM.

I'd guess we need to pitch the prop for 5000 to 5200 RPM static WOT.

Doug

It would help if Rotax would clear this up but until then I wouldn't set my static RPM to 5200. First, this is a service letter and is recommended, not mandatory. Second, it says continuous WOT below 5200 RPM should be avoided, and finally, it says take off RPM should not be below 5200.

Taking all this together, if I do anything, I will repitch to give me 5200 WOT at an 80K climb. Right now i have about 5000 RPM. I would also be interested in what FD has to say.

I consulted with my Rotax Distributor, They suggested 5000 Static as a minimum. I'm pitched to 5090