Oil pressure drop

I don’t have my engine in operation yet as my build is still a year or so away from first flight so I can’t speak from specific Rotax experience.  However, I have 50 or so years of working with and overhauling a number of engines from motorcycles to diesels and I would be more worried about the erratic oil pressure regions on the graph than the 29 psi areas which seem to have steadier readings.  It almost looks like the system is sucking air as that is generally what makes oil pressure jump around erratically.

Have you checked the crankcase pressure to ensure it is in spec?  If oil isn’t being scavenged from the crankcase quickly enough, the reservoir might get low and suck air, but it seems unlikely that would get worse with altitude.  If anything, I would think it would get better as the lower ambient pressure should increase the differential with the crankcase.

Might want to call Dean Vogel @ Lockwood as he’s got a ton of experience with these engines.

Lots of good ideas in this thread:

https://dev310.rotaxowner.com/en/912is-technical-questions/6689-oil-psi-drops-the-higher-i-climb?start=35