Why is the autorotation Vne different from the powered flight Vne?
In training aircraft there is usually no difference and you will not likely be aware that in some aircraft there is a different Vne for autorotation. Autorotation Vne is usually marked on the airspeed indicator of a helicopter by a blue radial line. This exists on larger helicopters which are faster than training aircraft. Take the Robinson R44 for example; this aircraft has an autorotation Vne of 100 knots, and is depicted by the blue radial line on the airspeed indicator. The Bell 206 Jet Ranger is similar. Remember that the up-flow of air through the main rotor is what drives the rotor system while in autorotation. If your airspeed is to high, you will not be able to achieve sufficient up-flow, and the rotor rpm will decrease. Advanced Autorotation Techniques Once a pilot becomes comfortable with autorotation, and once he or she sees and understands that the helicopter does not fly any different in autorotation than it does in powered flight, then these techniques can be taught, use
