inertia would keep the aircraft going up following an engine malfunction and that it may not be possible to get into autorotation
Now there's a thought! In the Pitts there's a manouver that in theory ends up with you in an inverted flat spin, right way up and going upwards. I've never actually managed to pull this off, nor seen it demonstrated, but that's the theory (it's called a "zwiebelturm", at least by my instructor).
I guess you could imagine something similar in a heli... engine stops while zooming up at 4000 fpm, rotor slows, instinctively drop the collective (making things worse), rotor stalls inverted. Anyone who understands the aerodynamics of all this care to comment?