Just a quick question requiring a quick answer
 

I've got to write a statement in the engineering report for a aviation regulatory body regarding the roll rate with different speeds for a new helo FTD.
I'd expect the roll rate of the AS350BA (or any helo for that matter) to be nearly the same at 50KTS
and 100KTS. Is this assumption correct? How could I argue about that? Or
is it not correct?

Thanks...

Let us know which body you're dealing with if you want the rules.

In general, it should not be required to make the roll rates identical. There shouldn't be a huge surprise at any speed, i.e. the helicopter should behave simliarly, but its reasonable to expect differences. If you compare it to fixed wing aircraft, they typically have lower roll rates for the same input at low speeds over high speeds.

The maximum roll rate for many helos is not affected strongly by forward speed as long as stall is not reached. Up to perhaps .6Vne the roll rate should be too high to be a factor in any FTD evaluation. I have experienced 130 degrees per second in several Sikorsky helos. What FTD needs to worry about that?

Do you mean control power - roll rate for 1" of lateral stick? Even so, this is largely unaffected by forward speed.

The FTD approval requires that roll rate be demonstrated at two different airspeeds. Depending on the level of approval, the tolerance of matching the rate of the FTD to the real helicopter rate varies.
And that's just one of the vagaries of trying to get an FTD approved.
The one that gets me is 'Landing' where the FTD profile has to match the real helicopter profile very closely, including pitch attitudes, etc. It's one of the many carry-overs from the fixed wing world. Sigh.