Is it possible to adjust the breakaway torque of the slipper clutch or does the complete clutch assembly have to be replaced if the measured torque is below or above spec? If it can, is it best to set it at the low, mid or high end of the allowable range of between 600 and 800Nm?

  • Re: Is it possible to adjust the slipper clutch?

    by » 12 years ago

    Hi Harri,

    You can't adjust the clutch itself. If it needs service it should go to a service center where it will be checked, disassembled, cleaned and reassembled to spec. You can adjust the friction torque in the gearbox with shimming of the Bellville washers. This is all a gearbox should need which should include a gearbox inspection when needed. If you don't mess the gearbox up it should go to TBO. If you use standard car oil, regular petroleum oil, 100LL you are going to have some issues before TBO. Using the wrong oil could be expensive.

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

  • Re: Is it possible to adjust the slipper clutch?

    by » 12 years ago

    Hi Roger,

    SI 02-1993 introduces the optional overload clutch for the 912UL. It states that the friction torque should be 450Nm +/- 30Nm and that the pre-tension is set by the collar nut M102. The SI has been superseded by the latest version of the maintenance manual which states that the correct breakaway torque is between 600 and 800Nm. When a gearbox with overload clutch is sent to a service center for the 1000h (or 600h if run over 30% of the time with 100LL) inspection shouldn´t the breakaway torque be set to the new recommended value as normal procedure since the gearbox is disassembled anyway? Wouldn't that happen by tightening the collar nut M102 a bit to increase the tension of the disk springs inside the overload clutch?


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