Mmmm ...
I believe the Hydraulic system on the BK117 and the EC145 (BK117C ??) is basically the same Hydraulic pack as also used on the Bo105 series (with some subtle variation).
It DOES run off the main transmission and thus when the rotors are stopped there is NO hyd. pressure. As well as this the Rotor Brake on these aircraft is not one of their strongest features ... and I really doubt that it would stop the rotors with any kind of power applied to them.
Having said that ... although I have many hours in the 105/117 I have not flown the 145.
