fbpx

 

As i read the maintenance manuals for the 912uls, the carbs should be disassembled and inspected every 200 hours, but replacement of components (including rubber components) is on condition, not at any set time. Is this correct?

thanks,

Key
  • Re: schedule for carburetor overhaul?

    by » 12 years ago


    Hi, I believe the 5 yr rubber replacement recommendation applies to the carb o-rings , gaskets and diaphragms.

  • Re: schedule for carburetor overhaul?

    by » 12 years ago


    Thanks--i needed that info for tomorrow!
    key

  • Re: schedule for carburetor overhaul?

    by » 12 years ago


    Key,

    Kevin is right. All rubber components in the engine and carbs should be replaced at five year intervals. This replacement does not relate to engine hours but is based on engine age.

    Bill.

  • Re: schedule for carburetor overhaul?

    by » 12 years ago


    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

  • Re: schedule for carburetor overhaul?

    by » 12 years ago


    Hi Al

    I hear what you are saying, but I would suggest the carbs are serviced at the recommended intervals.

    You need to strip the carb to see if the needle is showing signs of wear. On the two strokes the retaining clip used to cut the needle in half and the needle would drop into the needle jet, causing and engine failure, even though ten seconds earlier it was running perfectly.

    The float hinges wear through with time and vibration where they pivot on the hinge pin. I have seen these break off and the needle valve falls out causing an engine failure.

    Float can disintegrate and float pins wear, some more than others, and the thing is every aircraft is different. They have different levels of vibrations and they resonate at different frequencies which means that one aircraft might last forever and another will wear after a couple of hundred hours, or less.

    Stick to what the manufacturers recommend, they are speaking from experience.

    Mark

You do not have permissions to reply to this topic.