Turboshaft, judging by your home plate, I'll be you are just the guy to answer the question! Did you know Jack Schweibold?
Xnr, I still have no feedback from Dave Wright, who is traveling and out of touch. I will take a swing at it and say that most such limits are associated with uneven temperatures on the rotating parts that might cause slight out of balace, and when the engine is accelerated, they can cause large oscillations and rubs which can damage the shroud tips as the shafts pass through the resonant speeds.
Turboshaft, is that at all correct?
Regarding the procedures, I can dig up the suppliment numbers, but they are the heliport and helideck procedures, where there is Cat A capability from small ground level and elevated decks.
The landbacks are purely vertical, so there is no ground run, for sure!
Sorry for the delay in posting a reply, my computer went on the fritz for a few days, turned out to be bad memory.