For those who are wishing to learn from these threads it may be a good idea to relate a bit about the whirlmode RPM as well. I don't have the book in front of me so rather than guess maybe someone else who has can look it up.
For the newbies, the onset of whirlmode is very sudden and is where the T/R drive shaft goes out of whack so far that it self destructs, taking half the tail boom with it. It probably is a sort of eye watering, ear wax popping excitement experience, followed by a quick stop from the vertical terminal descent speed approach profile. Your arrival airspeed of course will depend upon the height of entry, but any higher than ten feet is most likely academic
At every hundred hourly inspection, the run out limits on the T/R drive shaft are checked to ensure someone hasn't been doing something that they should have spoken about.
Now tell me, are you still dithering about marching right into the CFI right now, and talking it over.
yessir, the red line is there to be not abused and if done so accidentally, please make a breast of it.
all the best tet