My question is related to the interval operating hours inspection for the propeller gearbox.

1 - Does this inspection need to be done at 600 hours or 1000 hours?

2 - Is my gearbox equipped with or without overload clutch?

3 - is there any SB (mandatory or not) to upgrade/downgrade the overload clutch PN?

4 - is there any documentation, specific to each engine, where is listed avery PN installed? (from manufacturer)

According to the manual (see picture), the inspection has to be done at 600 hours only if the installed overload clutch PN is 996886 and the use of leaded fuel is more than 30% of operation. I think the PN 996886 is not related nor installed to this specific engine, in adition, the use of leaded fuel stays way under the 30% (we use regular 95 octane fuel). Therefore, in my interpretation, I need to perform this inspection only at 1000 hours


In addition, the only SB related to this matter, is the SB-912-033-UL which is only rekated to the engines version UL*3, and I have the ULS2.

References: Manual 899196 (Maintenance Manual Line for Engine Type 912 Series Edition 4 Revision 1)

Engine specs retrieved from the Rotax website:





  • without 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 nipple conn. for oil pump
  • with expansion tank
  • without air box
  • without engine truss
  • starter large


Many thanks in advance.

Paulo Martins

10096_1_MML 899196.png (You do not have access to download this file.)
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