torque cont'd...
Torque in turboshaft engines in helicopters is expressed as a percent, with 100 percent being the maximum allowable, at least in the Bell 206 Jetranger. If you exceed 100 percent you are "overtorquing" which could damage the engine.
Also in turbine helicopters, the engine and rotor speeds remain constant through the use of a governor. As the pilot increases the pitch of the blades through the collective, the torque required will also increase as the blades require more power to maintain their speed due to more induced drag.
Torque is measured in foot-pounds in the English system. The simplest definition I have heard is that torque is "twist force" as opposed to straight line force.
Hope this sheds some light on the subject.