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Check this at your next annual

WingedFrog

Well Known Member
During my annual inspection I caught a broken bracket under the ignition module. I caught it by chance just because the vibration had created a polished crack that reflected my torch light. Very tight place, no easy access for repair and after finding how this bracket was made originally by Rotax (by bending 90 deg a pretty thick piece of Al), I decided to fabricate one (out of an Al angle) that should be less likely to crack. I suspect that I missed this broken bracket at my last annual because it was not polished enough... :D

Here is the faulty bracket with the new one I fabricated:

IMG_0609.JPG


Here is the location where the bracket can be inspected (the new bracket shown here after repair):

IMG_0610.JPG

You can easily understand why this cracked bracket might be difficult to detect (although I found afterward that pulling the ignition module up will show the crack once the bracket is broken)
 
You really shouldn't use a torch within 50 feet of flammable liquids such as gasoline...just sayin.
 
I believe Jean-Pierre is from either Canada or France - a "torch" is a flashlight to them.
 
I know what he meant...just joking. Glad you found the cracked bracket. That new bracket should do the trick.
 
Jack and Bob: are you sure about the number of hours when your bracket failed? As I mentioned, the failure may go unnoticed as there is little consequences to it. Indeed the ignition stack is set on the top of 3 "silent blocks" (an other French term?) of generous dimensions regarding the mass they support. Only one of these rubber dampers is using this type of bracket, the two others have a sturdier attachment. What I don't understand is why Rotax, with all it's mechanical wherewithal, is using a bent piece of thick aluminum for a bracket.:confused:
 
I see two possible issues with your new bracket;
1 - It looks like it is not the structural Al angle, no radius in the inside corner
2 - There appears to be a notch in the inside corner of the new angle, which may be a new failure point.

My questions are only based upon the image and may not be accurate.
 
My question, is an aluminum angle as strong as bent aluminum? Maybe it is stronger? I do agree the angle in the picture does not look like structural angle.


I see two possible issues with your new bracket;
1 - It looks like it is not the structural Al angle, no radius in the inside corner
2 - There appears to be a notch in the inside corner of the new angle, which may be a new failure point.

My questions are only based upon the image and may not be accurate.
 
I see two possible issues with your new bracket;
1 - It looks like it is not the structural Al angle, no radius in the inside corner
2 - There appears to be a notch in the inside corner of the new angle, which may be a new failure point.

My questions are only based upon the image and may not be accurate.

I fabricated the bracket in my hangar from an angle scrap. I had to shave some material to provide clearance for the bolt head. It's quite possible that there are some weak spots. One sure thing, I will keep an eye on it and if it fails I will know how to make the repair.
 
Maybe it's just me, but given the long term performance of aluminum under vibration and flex loads, I'd be more tempted to make a replacement from stainless or maybe primed/painted 4130 sheet. AL seems to be a less than ideal choice for a mounting bracket like that. But I'm no engineer, so don't take my word for it.
 
Seems like the original bracket probably had a lot of residual stress from forming the 90 degree bend. At least the extruded angle used for the repair won't have that. I'm not a metallurgist, but any metal is subject to fatigue effects.
 
I'm going with improper primer selection and application. :D

Depending upon how much load there is (I have no idea.....) the aluminum might be fine. If it sees a lot of vibration/load, steel might be the ticket.
 
At 150 hours total time found the same bracket broken. Thanks for the heads up.

Good (or bad?;)) to know my case is not isolated, this might motivate other RV-12/912 ULS users to take this warning into account. Did you order a replacement part from Lockwood or did you fabricate one? (I am just curious to find out if Rotax is still using the same part.)
 
I see two possible issues with your new bracket;
1 - It looks like it is not the structural Al angle, no radius in the inside corner
2 - There appears to be a notch in the inside corner of the new angle, which may be a new failure point.

My questions are only based upon the image and may not be accurate.

Yes it looks like decorative architectural angle. It will likely fail as well. Structural angle has a generous fillet which will improve fatigue life.
 
Yes it looks like decorative architectural angle. It will likely fail as well. Structural angle has a generous fillet which will improve fatigue life.

I do not believe you need a structural angle here. The ignition boxes are light and stacked on the angle, they are also supported by two rubber dampers on the opposite side of the bracket and the bracket itself is attached to a third rubber block. This is probably the reason Rotax chose to make the angle out of a bent aluminum bar. It is why the broken brackets are difficult to detect as there is no consequence beside a rubbing of the two broken pieces of the bracket. I suspect the original bracket failed from the thermal cycles, not under mechanical stress.
 
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I agree. This seems like a low usage application. My guess is the failure is due to high residual stress from bending, more than in service cycles.
 
Good (or bad?;)) to know my case is not isolated, this might motivate other RV-12/912 ULS users to take this warning into account. Did you order a replacement part from Lockwood or did you fabricate one? (I am just curious to find out if Rotax is still using the same part.)

I ordered a length of 0.125" T-316 Stainless Angle to fabricate a new bracket. If anyone sees a problem with this material for the new bracket please let me know.

 
I ordered a length of 0.125" T-316 Stainless Angle to fabricate a new bracket. If anyone sees a problem with this material for the new bracket please let me know.


I'm with you....I've got zero hours, but with everything open....seems like good preventive maintenance.
 
additional item to check?

While replacing the broken bracket I lifted the coils beneath the ignition modules and found the powder coating worn completely through (located at the end of the red line).I primed and painted this small area then used a washer at each end of the coil attachment to shim vertically and prevent further abrasion.

403a6f8d-94a8-47ce-848d-76bb7c44ce33.jpg
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Yes and it's a tool that could be precious to VANs too... If they want to listen to their customers rather than to their lawyers!

Kind of a cheap shot don't you think Jean-Pierre?

I know you haven't been around here since the very beginning, but you have been here for quite a while so I know you have seen the huge # of times there has been a response to things posted here in the forums.
Everything from answering questions to instituting design changes as a result of customer input.

And all of that when there is actually an official means of making contact with someone in engineering if a service difficulty is discovered .

It is clearly described in the RV-12 Maint. Manual, but very few seem to be aware of it.
 
Kind of a cheap shot don't you think Jean-Pierre?

I know you haven't been around here since the very beginning, but you have been here for quite a while so I know you have seen the huge # of times there has been a response to things posted here in the forums.
Everything from answering questions to instituting design changes as a result of customer input.

And all of that when there is actually an official means of making contact with someone in engineering if a service difficulty is discovered .

It is clearly described in the RV-12 Maint. Manual, but very few seem to be aware of it.


Have to agree with Scott on this one...:cool:
 
Come on guys! It's just his opinion. What happened to the country that guaranteed free speech? We don't have to like the points of view, but we should tolerate them as long as they are presented civilly.
 
Come on guys! It's just his opinion. What happened to the country that guaranteed free speech? We don't have to like the points of view, but we should tolerate them as long as they are presented civilly.

Thank you Rich!
The only thing missing was a request to ban me forever from the VAF Forum to give me the feeling I was facing a lynching mob :eek:
 
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
 
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.
 
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?
 
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.
 
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-blog/item/57-vibration-help
 
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.
 
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.
 
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!
 
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.

Never balanced eh?
 
Been meaning to post this. I went ahead and fabricated a very basic replacement ignition coil bracket from some scrap aluminum angle I had in the hanger. But, before installing it a friend at the airport dropped by, who has a machine shop and also an amazing basement workshop, and insisted that we fabricate a more durable replacement out of 4140 steel that would be less prone to break again. I shot this short video for our EAA chapter (we're going to visit his basement in a few months). He added a third side to the bracket to strengthen it, but (not in the video) I needed to remove much of that in order to be able to get a small wrench in there to reinstall the bracket on the engine. Those of you have have had to make this repair know how tight it is in there.

Over engineered. YES. But was really interesting to see a skilled machinist in action. After weeks of maintenance in abnormally cold spring weather, several SBs, and this last repair, the annual inspection that wouldn't end is finally done...:D

P.S. if you check Lockwood's website, the replacement bracket (# 851260) can be purchased for something like $11 (surprisingly cheap compared to most Rotax part prices). So if this one fails, I'm obviously just going to buy the next one.

https://youtu.be/dFLTrf4WRl4

i6dph3.jpg
 
Bracket

I see a great item taking care of a problem nothing over engineered here just done to fix a problem like Rotax should have done years back. The metal remaining is more than enough to take care of the problem. Well done and hey guys, a small milling machine and a mid sized lathe are in my garage and have been used on many things other than my large scale trains.
 
My German cousin is a ROTAX mechanic. He got me a couple of replacement brackets, and he said this issue is not common to other aircraft types. Seems weird we are so ?blessed? in the RV-12 world.

I took all the dimensions on the ROTAX parts so I can make replacements in the future.
 
It looks like most ignition mounting bracket failures are the stubby 90 degree brackets on the back of the ignition coils. I have not had this failure, but now at my latest oil change (325TT), I noticed the long front bracket has failed just below the 90 degree bend. This is PN 29 in the attached drawing. The bracket is 0.080” Stainless Steel. I have fabricated a new bracket from 1/8” mild steel and added 1/8” to the overall width for additional strength.

Attached photos show broken bracket and 1st iteration of new bracket to test fit. A second more professional bracket is now installed on the engine.
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