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Hi Everyone

I don't get on this forum nearly enough; if I missed a post in my search on this, please excuse me.

What's the latest experience with carb floats? I just did my first Annual on my 912ULS (in a Magni gyro, 81 hours, all Premium mogas, plus routinely using StaBil) and the floats were heavy: 7.7g on one side, 8.6g on the other. The engine was produced April 2018 and I don't see a part number or the 2- or 3-dimples on the floats I've heard of. I'm guessing they're 861-188's, based on the engine manufacture date? They all have a number next to the Bing "B" which I'm hoping are not dates of manufacture: 2/14, 2/10, 4/11, 2/5. The brass sleeve does NOT extend up past the hole.

I just put in 861-189's from Lockwood, so we'll see how they survive. Of note, CPS seems to be selling the -188's: when I just searched their site again for "861-189", a promising link comes up but when you click on it, both the title and the Overview indicate they're actually -188's.

What's the latest guidance for checking these? The MML seems to say 200 hours "or annual check". Given that my new ones, at 81 hours, were fairly well past spec, would it make sense to check them at each oil change? I don't personally like manipulating the carb any more than necessary, but the fact that these "fixed" ones were out of spec well before 200 hours is disconcerting.

I know some comments were made under a Marvel Schreiber thread but I thought I'd make this more Rotax/Bing float specific.

Thanks!

/Ed
  • Re: Latest on Carb Floats?

    by » 5 years ago


    I am also curious about this.  Seems there is still a problem with the replacement floats with dimples (861-188), and a newer PN 861-189 available except this time Rotax is charging full price for them, no discount.

    Ed, how have the new ones worked out for you?


  • Re: Latest on Carb Floats?

    by » 5 years ago


    What's the latest guidance for checking these?  It's still "every 200 hr. (or annual check)" as specified in the LMM (Latest edition Feb 2015).

    This is the standard check, and only once has it ever been recommended to check more frequently.

    In March 2015, the SB-912-065 came out and it instructed:
    'Carry out this inspection of float buoyancy of the engines listed in section 1.1.[A LIMITED RANGE OF SERIAL NUMBERS], according to the instructions in section 3 periodically after each 25 hours of operation, but at the latest after 60 days.'

    That was not a general instruction for all engines, but only for that limited range suspected to have bad floats. It also specified: 'The inspection [of that limited range] must be continued even after a replacement of the float, until new and improved floats are available. Only from this point of time the periodic inspection can be stopped.'

    The float part number at that time was 861184.

    March 2015 also saw the release of SB-912-067, which advised that ALL 'floats with the part no. 861184, which have not been marked' (since july 2012) were to be replaced with 'marked' 81184 floats (one or two dots).

    In July 2016 asb-912-069 came out - again aimed only at a limited range of serial numbers, and it instructed the use of 861185 floats to replace floats 'in the limited range affected by the ASB' (Note that this was not a general call for replacement of all 861184 floats, as the majority of them were perfectly good).  861185 did in fact replace the 861184 in production that year...

    Finally, in May 2017 the SI-912-029 is released offering 861188 floats. These are specified in the SI as replacements for 861185 floats.  These floats actually have a substantial design change from 861184/861185.

    New part number 861189 floats have recently superseded the 861188 but only due to a change of float suppliers. (Not a change of design, there are no known issues with 861188 floats!)


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