twright 7 Posted January 18, 2009 Share Posted January 18, 2009 Hi again!Further to my earlier question about the prop levers, I'd like to ask about the torque pressure for the smaller engines on the -100 variant of the Twotter. Pushing the throttles to maximum, the torque pressure needles overshoot the red line by quite a bit (about 10PSI), so I have to reduce the throttles to about 75% (on the throttle lever tooltip) to get them just under the red line. Is this normal behavior?Thanks,Tom Link to comment Share on other sites More sharing options...
Snave 466 Posted January 18, 2009 Share Posted January 18, 2009 Hi again!Further to my earlier question about the prop levers, I'd like to ask about the torque pressure for the smaller engines on the -100 variant of the Twotter. Pushing the throttles to maximum, the torque pressure needles overshoot the red line by quite a bit (about 10PSI), so I have to reduce the throttles to about 75% (on the throttle lever tooltip) to get them just under the red line. Is this normal behavior?Thanks,TomSounds more like operator error. If you move the power levers too fast you can generate an `overboost` situation, particularly with free turbines such as the PT6, so power control management is normally done slowly to avoid surge and lag. When spooling up for take-off, move the levers smoothly to about 50%, then wait for the engines to stabilise before smoothly and slowly increasing to take-off power. `Setting the needles` is the correct method of operation for a turboprop engine, whereas you can normally advance the levers to full in a piston prop. This is the main difference in engine management between pistons and turbines. Link to comment Share on other sites More sharing options...
twright 7 Posted January 18, 2009 Author Share Posted January 18, 2009 Sounds more like operator error. If you move the power levers too fast you can generate an `overboost` situation, particularly with free turbines such as the PT6, so power control management is normally done slowly to avoid surge and lag. When spooling up for take-off, move the levers smoothly to about 50%, then wait for the engines to stabilise before smoothly and slowly increasing to take-off power. `Setting the needles` is the correct method of operation for a turboprop engine, whereas you can normally advance the levers to full in a piston prop. This is the main difference in engine management between pistons and turbines.Thanks for your reply. Doing as you suggest, takeoff power (redline) is set with the throttle levers at about 75% of their full travel.Also, the prop levers are reduced to 75% RPM on the gauge for cruise, but this is full rearward travel for the levers - is this correct?Many thanks,Tom Link to comment Share on other sites More sharing options...
Snave 466 Posted January 18, 2009 Share Posted January 18, 2009 Yes, the power levers of a turboprop function differently to a piston engines throttles. Which is why they go by different names. Link to comment Share on other sites More sharing options...
twright 7 Posted January 18, 2009 Author Share Posted January 18, 2009 Yes, the power levers of a turboprop function differently to a piston engines throttles. Which is why they go by different names.Ok thanks.Also, the propeller levers are reduced to 75% RPM on the gauge for cruise, but this is full rearward travel for the levers - is this correct? Link to comment Share on other sites More sharing options...
Albrecht 9 Posted January 18, 2009 Share Posted January 18, 2009 HI,very good question. As the prop levers are in the near of the zero-zone (and so sometimes funny things happens).Albrecht Link to comment Share on other sites More sharing options...
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