The maintenance schedule for the 912ULS says that at 600 hours I need to do a gearbox inspection but I read in another post that the inspection is at 1000 hours for the 2000hr TBO engine using leaded fuel less than 30% of the time but could not find this anywhere in the Rotax documentation.  Could someone point me to the right document?

I know this is wishful thinking but if I have used Decalin Runup consistently in the 100LL fuel, does that count as unleaded and extend my inspection to 1000 hours?

I have enjoyed doing all my own 100hr and 200hr engine work but after reading the heavy maintenance manual, its clear to me that inspecting the gearbox is something best left to a fully equipped Rotax shop.  Any ideas the approximate price for this inspection?




Engine Type: ROTAX 912 ULS
Engine Version: 912 ULS2-01
Model Number: 309120110

    with fuel lines
    UL2 I=2,43 with clutch
    without vacuum pump
    with green valve covers
    without mech. tachom. pick up
    without external generator
    without air guide baffle
    with std. temperatur sensors
    with screw connection UNF
    with expansion tank
    without air box
    without engine truss
    starter large

  • Re: Gearbox inspection at 600hr or 1000hr?

    by » 12 months ago

    Gearboxes with overload clutch inspection are required every 600 hours if the overload clutch part number 996886,  without lead drain holes, is installed and if the use of leaded fuel exceeds 30% of the engine's operation. The following engine types equipped with overload clutch without drain holes fall under this inspection requirement:

    • 912 A up to S/N 4410612 incl.
    • 912 F up to S/N 4412860 incl.
    • 912 S up to S/N 4922983 incl.
    • 912 UL up to S/N 4405961 incl.
    • 912 ULS up to S/N 9574657 incl.

    To verify whether the overload clutch has ever been changed during maintenance, service, or overhaul, please check your Maintenance Logs. It's important to note that the inspection interval remains the same for 912 engines that do not have an overload clutch installed.

    If the engine has an overload clutch but has lead drain holes, the inspection interval is extended to 1000 hours, regardless of the fuel type used. If you are running less than 30% Av-Gas, you can inspect the gearbox (regardless of the clutch) at 1000 hours. TCP or Declan play no role in the extension of your maintenance interval.

    For detailed maintenance intervals, please refer to the Rotax Line Maintenance Manual, Section 05-20-00, Pages 14 and 15. https://www.rotax-owner.com/pdf/MML_912-Series_Ed4-Rev1.pdf 

    Based on your engine serial number (S/N 309120110), indicates that your engine did not come with a clutch equipped with lead drain holes. However, it's important to check your engine maintenance log books to verify if your clutch has ever been changed to the new style (P/N 996 910). If your clutch has been upgraded to the new style with drain holes, the inspection interval is now extended to 1000 hours, regardless of the fuel type and percentage used. Please review your engine maintenance records to determine if your clutch has been replaced with the new style.

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