Prop feathering not affecting torque?
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I'm not sure if this is a new bug, or if I'm just not doing something right, but during the full preflight which I try to do once in a while to keep familiarity with the systems, I was not seeing the engine torque drop at all during the autofeather test procedure, or just feathering the prop manually. Shouldn't it go down to basically 0 if the props are feathered?
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Torque is a measurement. When the propellers feather, and all other parameters remain unchanged, torque actually increases due to more wind resistance. However, I did not reply as these days I have no time to research the effects of auto feather or manual feather. I believe Ng should drop as the prop is feathered and torque reading should go to a nominal value given systems operation and outside conditions. But iirc a feathered prop on an operating engine should never read 0.
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If torque is 0 (because negative values aren't shown), it's highly likely the propeller is driving the engine, which is is very bad on direct drive turboprops (might have a system to prevent that, NTS comes to mind), while on free turbines is fine.
Measurement is done between engine and propeller, not propeller to air. On ground, in feather will be greater than unfeathered. In air, depends on conditions. It's possible for airflow to still drive it more than the engine, but theoretically no, so should indicate something.
