I'm not an A&P or greatly Rotax experienced, so although I'm a decent mechanic, take what I say next with a grain of salt:
On the Rotax and indeed the whole aircraft seems to me we should always be balancing between
"an ounce of prevention is worth a pound of cure" and doing the sort of proactive maintainance and replacements Rotax recomends,
AND ON THE OTHER HAND
take seriously the "It it ain't broke, don't fix it."
Talk to any honest A&P and I bet they have lots of stories of someone, or even they, taking apart some subsystem that was working properly, putting it back together, and having problems with it.
So one thing to think about in doing "preventive overhaul" -- particularly if it's expensive or challenging -- be it on carbs or anything is this:
If you DON'T do the preventive overhaul and it turns out it REALLY was needed, what's the worst that can happen? Could it (a) cause a serious accident and/or (b) cause more complicated or costly repairs due to the neglect? OR would it not serious? Could you just wait until that subsystem shows symptoms of failure or sub-optimal function?
In short, in my opinion, and in the opinion of several far-more-expert-than-me A&P folks, there are some things, even on ADs, that it is better, and safe, to leave alone and wait until they actually fail or show symptom of failure, if ever, rather than doing proactive maintainance or replacement.
Of course there are places that it is foolish, dangerous, and illegal to neglect.
And in some cases, especially with standard category aircraft where it's illegal to defer maintainence. But if it's not one of those cases ........
In the case of a carb overhaul that is deffered longer than officially recommended or even longer than it should be for functionality, IMO the worst that's likely will happen is that you will get some loss of power and loss of fuel efficiency.
If your plugs are reading right (not indicating you're running too rich nor too hot/lean) and you're getting normal power and normal fuel consumption, idle and cruise is smooth, your carbs are working right, and in my opinion personallyI wouldn't touch them unless you just have TOO much free time on your hands :unsure: .... except take off the bowls to check for sediment. If you take the bowls off it's a good idea to have at hand spare new bowl gaskets BEFORE you remove them.
We periodically put a bottle of NAPA carb cleaner through our fuel tank. $3 per bottle.
My very unofficial two cents.
Al
