New carb socket fits loose

Kelsie,

Did you reach out to the manufacturer of your airplane to ask if shortening the clamp spacer by a mm or so would be considered a modification and require their approval? As that clamp is a genuine Rotax part it may help during that call to add that you have an opinion from a certified Rotax technical expert as to what, if any, operational or safety concerns may arise as a result. 

You can keep the original spacer. 
Just go down to the hardware store and buy a new 1” long tube that you can cut to 7mm for a test. You can use a Dremel tool to trim it down to the 7mm spec for your test.

It’s just a test for now. I’ve never seen a lose carb and socket like this. So there must be something we aren’t seeing. I’ve seen sockets so tight that owners don’t get them fully seated and then they are lose, but never when pushed in all the way. Usually you can hear and feel them snap in place when they fully seat. Some carbs you have to tilt back and forth and push fairly hard to seat them.

Something just seems amiss.

Roger Lee wrote:

You can keep the original spacer. 
Just go down to the hardware store and buy a new 1” long tube that you can cut to 7mm for a test. You can use a Dremel tool to trim it down to the 7mm spec for your test.

It’s just a test for now. I’ve never seen a lose carb and socket like this. So there must be something we aren’t seeing. I’ve seen sockets so tight that owners don’t get them fully seated and then they are lose, but never when pushed in all the way. Usually you can hear and feel them snap in place when they fully seat. Some carbs you have to tilt back and forth and push fairly hard to seat them.

Something just seems amiss.

You keep going back to the carb seating thing, but its not like its hard to tell. It's kind of obvious if its seated or not. I shared pictures earlier in the thread of it seated. I don't need to shave a spacer to know that I can get it tight if the spacer were shorter, because as you can see a couple of posts ago, I found that my older clamps are tighter, because the spacer is wedging into the nut side a bit, taking off about 1mm on the spacing. We already know the answer that this test would yield at this point.

Jim Isaacs wrote:

Kelsie,

Did you reach out to the manufacturer of your airplane to ask if shortening the clamp spacer by a mm or so would be considered a modification and require their approval? As that clamp is a genuine Rotax part it may help during that call to add that you have an opinion from a certified Rotax technical expert as to what, if any, operational or safety concerns may arise as a result. 

The regulations are quite simple. If the maintenance manual or any official document it defers to contains the instruction, then it can be done. If it is not included, it is considered a "major repair", and requires a Major Repair Authorization. Even though common sense says this is "minor", that is how the standards are written.

There is nowhere in any of the RV-12 documentation or Rotax documentation that I'm aware of that describes adjusting or shortening the spacer, so the regulation is simple- you must not do it on an SLSA without explicit manufacturer approval.

If there is some documentation on this that I have missed, I would love to know about it, but I do not currently believe it exists.

Vans does not seem particularly keen in general on solving one-off problems with authorizations, and getting them to write a service update is a lengthy process. Besides, this is a Rotax problem, and they will most likely tell me to go to Rotax to figure it out.

Aha so we have progress. Time to go to Rotax and ask for assistance. Lockwood is close to you I believe.