The start of a new adventure begins with a Vortex

1800 is not too low... There is some other reason for that kind of a failure.
You might bring that one up at the rotax-owner.com forum. It's $25 a year for full privileges (like viewing full-sized pics and posting questions) but well worth it, IMO.
That sounds like a good idea, I do not like not knowing why this happened.
 
Tyger, not sure if you have much experience with Rotax two strokes.

Even the four strokes will shake and rattle if the idle is set too low, but the two strokes do it very badly if the idle is too low.

Generally, about 2000 rpm is where the engine and gearbox and prop smooth out. In some set up's you it will run smooth a little lower than 2K and in others it will need to be a little higher than 2K, but regardless.... You need to always try to keep the engine idle speed high enough that it runs smoothly and no shaking or rattles.

On my aircraft, I will NOT set the idle on the carbs high enough to run smoothly. I Just advance the throttle lever forward enough to idle smoothly once the engine starts. I do this because once airborne, due to the air flowing through the prop, your " in air " idle speed will be a few hundred RPM higher than your static on ground rpm. So in the air you can pull the lever all the way back to idle and have a smooth idling engine.... If you set the RPM to 2000 or above on the ground, in air your idle will be perhaps 2500 or so and you will always have a little push of thrust even at idle. Not sure if that all makes sense the way I describe it... But for example its the same thing on my airplane... I have the idle set to like 500 rpm on my O-320 in my RV4, but on final as I am coming in to land, ill be showing 850-900 rpm. at 500 rpm the engine barely wants to run, so on the ground I keep the throttle lever slightly advanced. If I set the static rpm for say 750-800 rpm, the airplane is hard to get slowed down on final and will " Float " down the runway much further before its done flying.

The higher idle speed the two strokes need, is one of the reasons the RK-400 clutch is so popular. With the Clutch, the engine idles much lower rpm and idles smoothly with the prop sitting still. Advance the throttle and around 1800-2000 rpms the clutch engages and the prop starts spinning and everything stays smooth.


The fact that Davids gearbox sheared those three bolts, Means to me that someone has operated for ALOT of time at too low of a rpm. And a Rotax engine shaking and rattling at that low of a rpm shakes the crap out of the entire machine. I would look real hard at all the engine mounting hardware as well as the entire airframe for cracks and wear.
 
Thank you for the thoughts Ron. I have 34 hours on it and and I always get the motor running smooth as soon as possible. I replaced the motor mounts and everything else looked good.
Have you ever heard of this happening?
 
Well I got the Vortex back in the air today, all good.
I started today with a great flight in my Mac.
 
Another GREAT flight
 
Thank you for the thoughts Ron. I have 34 hours on it and and I always get the motor running smooth as soon as possible. I replaced the motor mounts and everything else looked good.
Have you ever heard of this happening?
I still think the bolts were loose. Glad you’re in the air again.
 
I still think the bolts were loose. Glad you’re in the air again.
The bolts in the flange don't look like they moved. It would be great to have a definite answer, guessing sucks.
 
The bolts in the flange don't look like they moved. It would be great to have a definite answer, guessing sucks.
I personally never experienced it or even heard of it before. I have put about 350 hours on the two Sport Copters I've owned. 250 on the first and a little over 100 on the one I have now which has a 618. I'm guessing you have a 68 inch or 66 inch 3 blade prop.
 
I will be flying a cross country today. KAJO to F70 to OCN to L18 and back to KAJO. This will be my first solo cross country. I have it all planned and approved.
 
"Virgil Brigmann back on the air"
I finally got back in the sky yesterday!
An awesome flight for about an hour and 10 min.
On coming in for my landing I tried nosing over like in that Roy Davis video I sent you.
It works quite handily!
Now get your ifly and program in PGUM to your last leg and get on out here bro!
 
Glad to hear it Ben. I didn't try anything fancy today, just a good 4 hours of flight, 3 first time solo to new airports, 20 gallons of fuel and a whole new perspective on flying. I think I like it.
 
Even got some pics
 

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It's a lot more stable with a full fuel load
 

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