Check this at your next annual

[RFSchaller]

Jean-Pierre,

Thanks for your original post. I am doing my fourth annual and found this issue. It must have been broken for a while because the vertical part of the broken angle had sawed into the head of the 10mm bolt that fastens the horizontal part of the angle to the rubber shock isolator.

FYI I checked the original bracket with a magnet, and it is non-ferrous, probably aluminum, which is what I replaced it with. I think the problem is that the bolt holes in the angle are offset, and if the offset is not correct there is a constant force pulling the angle causing it to fail.

For anybody else who has this issue: be sure to put some material under the angle before you remove it because if anything drops there is a good chance it will go into the flywheel area where the generator, tach, trigger and ignition power coils are.

I had to disconnect my oil tank hoses to gain access to the fasteners.

Rich

[WingedFrog]

Originally Posted by RFSchaller

Jean-Pierre,

Thanks for your original post. I am doing my fourth annual and found this issue. It must have been broken for a while because the vertical part of the broken angle had sawed into the head of the 10mm bolt that fastens the horizontal part of the angle to the rubber shock isolator.

FYI I checked the original bracket with a magnet, and it is non-ferrous, probably aluminum, which is what I replaced it with. I think the problem is that the bolt holes in the angle are offset, and if the offset is not correct there is a constant force pulling the angle causing it to fail.

For anybody else who has this issue: be sure to put some material under the angle before you remove it because if anything drops there is a good chance it will go into the flywheel area where the generator, tach, trigger and ignition power coils are.

I had to disconnect my oil tank hoses to gain access to the fasteners.

Rich

Here we go again! Indeed it is a silent failure quite difficult to detect, because of the location and because of the minor consequences (at least for a while, indeed in your case it has probably been broken for more than one year). I still believe that this is due to the manufacturing process: folding a thick piece of Al alloy at a 90 deg angle. It could be that the wrong alloy was used in some instances otherwise the rate of failure should trigger a recall by Rotax.

[RFSchaller]

Possibly, but I think the alignment of the holes is a major contributor to the failure.

[RFSchaller]

Well, two years later in annual my bracket was cracked again. Again I made a beefier bracket out of 3/16? aluminum. My guess is I?ll be addressing this again in the future. Has anybody found a final fix for this?

[RFSchaller]

My German cousin is a light sport mechanic in Germany. I asked him if the failure of the coil bracket is common, and he said he has not seen any. It's not obvious to me as to why this would be an issue only on RV-12s. I put in a bracket that I manufactured from 3/16" Al angle, but I also ordered a replacement that I can reverse engineer to make any future brackets as required.

[Jolly]

Hi RFSchaller,

These brackets rarely break and they are mounted on over 50K engines. What causes this is just vibration. Doesn't matter if you can feel it if those brackets are breaking then you have vibration issues and should eliminate the possible causes. This vibration could cause other breakage issues down the road. Here is an article I read on Rotax-Owner on the common causes. We covered these vibration issues last week at CPS Heavy Maint. school.
Hope this helps.

https://www.rotax-owner.com/en/rotax...vibration-help

[RFSchaller]

Thanks, Brad. None of the suggestions are an obvious problem. I wonder if there are many RV12 owners who have experienced this. As I said my cousin, the ROTAX mechanic says he has not seen it as a problem on other 912ULS engines.

[PilotBrent]

Add me to the list of broken brackets. Saw it this weekend (420h) but it may have been there in the past and I never noticed it. Credit this post for even knowing where to look. Really don't think I have excessive vibration although I've never had the propeller balanced. Might be an argument to do that.

[Hotscam]

My bracket gave up at about 400 h and again at 700.
Prop has been dynamically balanced twice

[aerofurb]

I've seen two of these brackets break. One on a Tecnam P2002-JF (around 500 hours total time) and one on a Tecnam P2006T (twin - but only on one engine affected), TTAF around 200 hours.

A right pain to replace on certified aircraft with the single airbox in the way!