Yeah, it seems apparent to me that the OM is written by engineers and attorneys, not pilots. To complicate issues, airplane POH's have their own run-up procedures, which often conflict with those in the Rotax OM. I really wish Rotax would just come out and tell us what they want in plain language. And make it pragmatic, not just "check everything at all power settings" like I'm sure their attorneys would want!
My 2 cents:
The "cooling down phase" doesn't reference any temperature, it only says:
"Normally the cooling down of the engine during descending and taxiing will be sufficient to allow the engine to be shut off as soon as the aircraft stopped. At increased operating temperatures make an engine cooling run of at least minimum 2 minutes."
So, I just hack a clock to achieve 2 minutes at idle after landing. Most of the time taxing from the runway to the ramp is enough to accomplish this.
The OM says to do the Lane and Ignition check at 2500 RPM, so that's what I do. I also check the fuel pumps at that time. (OM says 2000 RPM for that.)
But then it also says to do a Wastegate and PCV check at WOT. (To me, doing full-power run-ups on a taxiway at a busy airport could be borderline unsafe.) Then, within the Wastegate and PCV check it also shows turning off the Lanes. I don't get what Lanes have to do with a Wastegate and PCV check. My thought is the clue lies in this statement in that section:
"If possible the PCV Check and the Lane and Ignition Check might be combined in one check."
So, I think what they're showing there is an example of checking the Lane and Ignition check at the same time as the Wastegate and PCV check. I don't think they're saying you have to do that at the same time. Happy to be corrected if I'm wrong.
They also say to set WOT to check if maximum performance can be reached.
So, what I do is do the Lane and Ignition check at 2500 per the OM, and I check the fuel pumps at that time. Cycle your prop as indicated in your prop manual. (Mine just says "Set normal engine run-up speed," So I just do it when I do the Lane and Ignition check. Yours may be different, depending on manufacturer.)
Then, when on the runway, powering up for takeoff, I check my engine instruments to assure I'm achieving full takeoff power, check that I'm not exceeding max manifold pressure (i.e., Wastegate and PCV are working), and that my RPM doesn't exceed limits.
Sure, you could do the WOT stuff on the taxiway / run-up pad, but be sure to clear the area behind you, and be sure your brakes hold! I think my method accomplishes the spirit everything in the Rotax OM, but I'm happy to hear other perspectives.
