The Flying Guide mentions a suggested cruise power setting of 950-1050 TRQ LB-FT for a typical ECON setting. What about RPM setting for ECON ? Perhaps the correct procedure is to leave the power levers constant and obtain the desired TRQ by adjusting RPM?

The Flying Guide mentions a suggested cruise power setting of 950-1050 TRQ LB-FT for a typical ECON setting. What about RPM setting for ECON ? Perhaps the correct procedure is to leave the power levers constant and obtain the desired TRQ by adjusting RPM?

Hi LPD,Torque in the Duke RISES slightly if you pull back the prop rpm. That's because a high prop angle puts more torque into the prop shaft, and creates more torque energy in the props themselves.So economy cruise is a combination of three things: lower power, lower prop rpm (despite slightly higher torque), and lower fuel flow. As I understand it, 2000 rpm and any throttle setting which gives comfortable Ng% and saves fuel, while not overstressing temperature, turbine speed or passenger comfort through engine noise.Thus typically, at FL250:2000 rpm (engines and prop are quieter)88-95% throttle depending on altitude and temperature outsideWell below 101.5% Turbine SpeedFuel flow at or below 30 GPH per engine.Speed will very much vary depending on altitude and ambient temperature, but you could expect anything from 260 - 275 knots economy cruise True Airspeed.Rob - RealAir

The Flying Guide mentions a suggested cruise power setting of 950-1050 TRQ LB-FT for a typical ECON setting. What about RPM setting for ECON ? Perhaps the correct procedure is to leave the power levers constant and obtain the desired TRQ by adjusting RPM?

These PT-6-35's like 2,200 rpm for takeoff and while you can climb with that setting 2,000 is frequently used. Remember to lower your torque before lowering the rpm as RealAir did correctly simulate this effect. Also watch your engine gauges during climb and adjust accordingly. For cruise 1,900 is a good setting and 1,800 can be used as an economy setting. Figure on around 1,000 lbs torque and 1,900 rpm for a 32-33 gph cruise fuel flow and you'll be right on the money and usually show a 197-200 KIAS.

Thanks to you both for the information. Rob, by the way, i'm still on a quest to obtain the POH, but i know it ain't gponna be easy.

Thanks for this detailed information Robert. Now I know why I couldn´t reach the desired cruise speeds, I was just too slow. Only a torque of about 820 in cruise... I will test the new setting right away.