WOT 5250-5300 rpm.
On cruise I was flying on 5000.
I don't know what was with previous owner, probably lower (I was changing prop pitch for higher rpm).
I set RPM due to this what rotax want (so higher) but in aeroplane manual you can read:
Neuform CR3 3 blade (1,75 m Ø)
Pitch 27º @ 310mm from hub edge
Full throttle ground static RPM 4700 rpm (prop = 1934 rpm)
If your max WOT rpm in flat and level flight was only 5200-5300 this may have caused these cracks from over stressing the engine. The 912 series engine should be no less than 5500+ WOT. I prefer 5600-5650 for a ground adjustable prop. Kind of balances the overall flight and performance characteristics. The older crankcases approximately May-June 2006 and older were prone to cracking from over stressing the crankcase because owners over pitched their props.
Aircraft MFG's get things wrong too. I have seen it many times. Some get the message right away and correct things and some don't.
Rob,
Do you think these cracks may have come from over pitching and stressing the case?
Roger Lee LSRM-A & Rotax Instructor & Rotax IRC Tucson, AZ Ryan Airfield (KRYN) 520-349-7056 Cell
I had 5200RPM WOT on the ground. I don't remember now what I had in the air but for sure more.
Previously (before me) was for sure more loaded because it was made according to Comco manual.
Hi Ron, I just lookeed at your post from 6 years ago. It seems I have exactly the same problem. Have you been able to fix yours? I have the (same kind of) leak on cylinder one and three? Any help would be much appreciated.
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