Shawn Coyle:
Just to clarify a point. There is no requirement in a Part 27 helicopter to stay out of the HV curve. Part 29, 10 passengers or more, there is a limitation on it.
There is also no HV curve information for a descent situation - the HV curve is published for takeoff power at a heavy weight, high density altitude from the hover to the 'knee' of the curve.
Oh? 'Scuze me Shawn, but where exactly is this explained or established in the RFM? The ones I've used and perused make no mention of where or when the H-V curve applies or does not. This business of, "the H-V chart only applies for MGW take-offs" is interesting and I've heard it a lot from quasi-authoritative sources, but might as well be an urban legend for all I know. Is that one of those nudge-nudge, wink-wink things? Maybe Bell, Eurocopter, et.al, plaster each chart with "FOR INFORMATIONAL PURPOSES ONLY!"
See, to us dumb pilots (you know, those of us who are
not test pilots), a chart is a chart is a chart. Without those little eyesight-straining explanations at the bottom, we might logically be expected to assume that the chart was applicable to all flight regimes.
Furthermore, I think asking pilots to disregard performance charts- even those "non-mandatory" ones like the H-V, is dangerous and irresponsible. Not to be insufferably pedantic (pretentious,
moi?), but if the manufacturers or the FAA want us to believe and act as though the H-V curve only applies in certain flight conditions, they can come out and say so.