Page 10 - October 23

I like this particular autothrottle feature very much: The ability for conservative pilots to set lower climb and cruise ITT limits ...”
1,300 RPM, say, while the other is at 1,150, then I will slow down or stop moving the faster side’s lever and keep advancing the slow side until they match. By the time 1,500 RPM is reached, the engines now tend to accelerate much faster and stay more synchronized. My attention stays on the prop tachometers to verify that both stop their increasing at 2,000 RPM, the takeoff setting for the 200-series. Only now does my attention shift to the Torque and
ITT gauges. And guess what? It’s right about now that AT takes over the power levers. Perfect!
What about the chance of Power Lever Migration (PLM)? As most readers know, power levers are spring-loaded toward idle, and the proper setting of the friction knobs are critical to prevent that from happening when the pilot’s hand leaves the levers to reach for the landing gear handle. The servos that move the power levers are mounted
within the cockpit pedestal. Setting friction too tight can prevent smooth AT operation and too loose can lead to PLM. As part of a cockpit preflight, it’s good to shove the power levers forward and make certain they don’t creep back. If they do, tighten the friction just enough so they don’t.
The autothrottle system abides by the AFM (Aircraft Flight Manual) limits – 2,230 ft-lbs or the ITT limit that varies depending on the dash number PT6 engine you have – until 400 feet AGL. Then it abides by climb limits: maximum torque until the climb ITT limit is reached. In cruise, the system knows both the maximum and normal cruise setting per the AFM and sets that torque. The props must still be controlled manually by the pilot. Golly, maybe that right arm won’t shrivel up from lack of use after all!
I like this particular autothrottle feature very much: The ability for conservative pilots to set lower climb ›
8 • KING AIR MAGAZINE
OCTOBER 2023