Question about engine torque falloff with altitude...

[Ballinger France]

Hi,

I'm by no means an expert in the field of turboprop engines like the PT6A-35 modeled on the Turbine Duke, but is the amount of torque decrease with altitude a normal characteristic of this engine or is perhaps some kind of torque limiting device (like a fuel control metering unit) being simulated? The reason I ask is because while available torque output decreases with altitude with all turboprop engines, the Turbine Duke engines seem like they would normally be limited by ITT temps, rather than torque limits at flight level altitudes. In the simulation, I can push up the engines all the way to the throttle stop limit at altitude (FL230-FL280) and never exceed max ITT. Available torque falls off to point that ITT always seems to stay in check when I would expect (from the reading on the subject I've done) that I should be hitting ITT max limit long before torque limits.

The Turbine Duke is hitting the numbers on the cruise charts in the manual though. I'm just confused about the readings I'm seeing.

Thanks!