Originally Posted by
verticalspin
I'm curious what Airbus' definition of a "fully developed" VRS is. I doubt very many instructors would let it get all the way to the 6000 fpm descent rate, which would be a fully developed VRS according to the books. The ones I have done were all recovered at the onset of the shutter/increased vibration and a continuously increasing rate of descent despite collective pull. So are they concerned with the increased vibrations that develop at the onset or the actual full blown thing with a 6k fpm drop rate?
AH doesn't give a definition, and probably due to the fact the SIN covers their entire fleet. However, I think it misleading to classify “fully developed VRS” just by a potentially
extreme achievable RoD. The FAA says, "A fully developed vortex ring state is characterized by an unstable condition in which the helicopter experiences uncommanded pitch and roll oscillations, has little or no collective authority, and achieves a descent rate that
may approach 6,000 feet per minute (fpm).”