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912 ULS gearbox problems.

in General Tech Discussion 9 years ago

  • Re: 912 ULS gearbox problems.

    by » 7 years ago

    In the turbine gearboxes of the jets and helicopters we use a little ammount of calcium sulfonate grease and this is far superior than the lithium grease, it supports hi temperature and very hard service, is totally compatible with any kind of oil and is the most anti oxidizing of all the greases and it is available and inexpensive, a small 250 cc tube cost you about $20 USD
      
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  • Re: 912 ULS gearbox problems.

    by » 7 years ago

    calcium sulfonate grease may not be suitable for our oil and in the gearbox. Just like we aren't supposed to use friction modifiers. This isn't a jet or heilo. Different parts and fluids.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: 912 ULS gearbox problems.

    by » 7 years ago

    My experience with the gearbox on an 912 --80 hp--, no slipper clutch:

    1400 hrs/8 years, carb sync check every 100 hrs. at least, 3 blade prop is static balanced, oil change every 100 hrs with Shell motorcyle oil, only autofuel with 10% alcohol:

    engine runs smooth, no vibration problems, no overhaul so far.

    In Germany the 80 hp is much more popular than the 100 hp Rotax.

    Leo
      
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  • Re: 912 ULS gearbox problems.

    by » 7 years ago

    calcium sulfonate grease may not be suitable for our oil and in the gearbox. Just like we aren't supposed to use friction modifiers. This isn't a jet or heilo. Different parts and fluids.


    Roger, maybe you have never seen a helicopter gearbox, here is one and it also have a clutch and is similar to the Rotax but a lot more complex because it has a lot of planetary gears and the calcium sulfonate grease have prooved to be the best and maybe Rotax must do some tests unless they want to sell a lot of gearbox parts.

    Rotax sugested to use Isoflex that is a garbage and is very acid.
    Kevin above sugested no to use Isoflex and use instead Lithium grease, now if you want the best protection for your gearboxes use calcium sulfonate grease, at least do a search about the properties of both kind of grease Calcium Sulfonate and Lithium and then decide what is best.

    I just repaired my gearbox that had a lot of wear in the dogs and used the calcium sulfonate grease, you think that I want to risk my plane or my life with a product that can be bad?

    Don´t be closed to improvements that has been proven in superior machines like certified turbine helicopters

    Regards


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  • Re: 912 ULS gearbox problems.

    by » 7 years ago

    Mi gearbox failed at 160 hrs and when I took it appart the dogs on the gears had a lot of wear to have only 160 hrs. I machinned my two gears and let the same finish and tolarances I posted many pictures but I can´t find that post but here are some before and after pictures after I machinned the gears lobes again.

    It was just a test and a risk because if I have to change the gears and dogs I don´t loose anything trying to fix it and today I tested the engine and the vibration dissapeared!!

    I was able to fix my old gears and did a very good job.

    I don´t advise to make it if you don´t know what are you doing and I have all kinds of CNC machine centers and tools to make this job, just to prove that it can be done.

    Now my advice is don´t trust Rotax for the momentum of the propeller, even with a propeller inside the Rotax numbers my gearbox was damaged, I used a Woodcomp in flight adjustable and the weight of this propeller made the Rotax gearbox to fail and cause a severe vibration at only 160 hrs. so use the lightest propeller you can if you don´t want to damage your gearbox.

    Regards



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