Originally Posted by tomerhm
so in transition from takeoff to climb power
when reducing torque to 1000, change rpm from 2200 to 2000 will rise torque around ~1300 ?
The torque would probably rise to 1200 to 1250. After it stablizes you can then gently adjust the power lever to get 1315.
Originally Posted by tomerhm
in take off, how mutch time take the engine to spool up from idle to takeoff power ?
The PT-6 engine in the C90 has a tendency for the ITT to increase sharply if you push the power lever forward too quickly from idle. You could easily exceed the ITT limit if you are not careful. The general technique if the engine is stabilized at idle is to move the power lever gently until you see that the ITT has recovered from its initial sudden rise. The other issue you run into is that usually one engine will accelerate somewhat faster than the other if you move the power levers too quickly. This causes a directional control disturbance when the prop rpm reaches 2200 rpm at different times, and the prop governors start adjusting each prop pitch to control the prop rpm.
So, when setting take-off power, move the power levers slowly until the ITT has recovered from its initial sudden spike, then more them more quickly until both props have achieved 2200 rpm, then set 1315 torque. At higher altitude, or warmer temperature, the engine will each 695 ITT before achieving 1315 torque, so you must use the lower torque for take-off.
The whole thing, from idle to take-off power, will take perhaps 6 or 8 seconds.