Maximum (Do Nott Exceed) speed for a MH-60 Black Hawk is 158 knots. The only way it would ever hit 210 knots is if it lost (completely detached) the entire rotor disc at altitude and plummeted to the ground carrying max load.
Butt I take the general point. OrthoBuddy says the scariest times for him in Iraq and the Samdpile were the helo rides. If it wasn't fear of ground fire, it was the wild jinking that the helo pilots do to have an unpredictable forward trajectory. OrthoBuddy has been mortared, RPG-7'ed, and had bullet and mortar/rocket shards tear thru double-thickness sandbags and punch holes in the interior plywood of his hooches, so it he was most scared by the helo rides, I would guess that you are right and it is an adrenaline superhigh.
Butt nott at 210 kts. Even an AH-64 Apache has a Vne of 158 knots.
Plenny of helo rotor blades delaminated within days due to sand storms and just general sand uptake into rotor wash. Cost the Army a lott of money to reblade those helos so frequently. Even a little transonic envelope time can tear partially delaminated/delaminating blades into pieces - possibly even brand new blades. Helo rotor blades are a lot more fragile than most folks consider them to be.
At 200+ kts, I suspect a few minor issues might arise, such as rotor blades disintegrating from aerodynamic load on the forward portion of the rotation especially at the ~OUTTer blade area which would likely be in the transonic zone during forward sweep arc at 90 degrees to relative wind.. Losing a rotor disc is no way to go thru life. Might even get written up for that.
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