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912UL Running Rough

in 912 / 914 Technical Questions 11 years ago

  • Re: 912UL Running Rough

    by » 11 years ago

    I would also look at the splines on the props shaft for wear. It's surprising how much vibration you get when throttling back if there is play between the prop shaft and dog. You won't notice it at tick over or full power.

    Mark
      
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  • Re: 912UL Running Rough

    by » 11 years ago

    Thats interesting Mark; back in 2000, in cooperation with the factory and the NTSB, we thoroughly tested every gearbox part, exchanged one at a time with known good parts, with spectrum vibration analysis equipment and we found that even severely worn splines contributed nothing to the vibration levels.
    The gearbox we tested shot over 20 IPS (worst case of gearbox wear we have ever seen). See attached samples from this testing.
    How did you analyze your findings?
    21.68IPSsample2.jpg (You do not have access to download this file.)
    DogGear.jpg (You do not have access to download this file.)
    DriveGear.jpg (You do not have access to download this file.)
    DogHub.jpg (You do not have access to download this file.)
    PropshaftSplines.jpg (You do not have access to download this file.)
    GoodVibSample.jpg (You do not have access to download this file.)
      
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  • Re: 912UL Running Rough

    by » 11 years ago

    All new gears and dog ring were installed in my gearbox due to some spauling on the engagement-ramps.

    The splines all looked in very good condition with minimal to no visible wear.

    Conversing with LEAF today they suggested possibly replacing the ignition switch (ACS Unit) with toggles. They also suggested I try the IVO Ultralight Patriot prop I have for another project to see if it makes any difference.
      
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  • Re: 912UL Running Rough

    by » 11 years ago

    Both good ideas. Its always a good idea to get rid of a rotary ignition switch and their eternal Airworthiness Directives.
    Keep the carb suggestion in mind though...
      
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  • Re: 912UL Running Rough

    by » 11 years ago

    It would be a good suggestion - inspection of the carbs - except I have had the carbs off, stripped and rebuilt them several times.

    Four, I think, at last count. :sick:
      
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