What is the IDLE propeller RPM?

• A. 1025
• B. 1000
• C. 1100
• D. 975

Answer: (A)

Idle propeller RPM is the speed the propeller governor targets when the power lever is set to idle. On the PC-12 NGX with a constant‑speed prop, the governor is tuned so the propeller sits at about 1,025 RPM at idle. This value is chosen to keep the engine running smoothly with light loads and to maintain adequate oil pressure and electrical system support while minimizing drag.

Why 1,025 works well: it’s high enough to ensure stable engine operation and reliable oil pressure at idle, and to prevent roughness or flameout that could occur if the prop were too slow. At the same time, it’s not so high that idle drag or unnecessary fuel consumption rise, which would waste power and heat the engine more than needed.

If the propeller spun noticeably slower, you could see rough idle and potential stability issues at light load. If it spun much faster, you’d incur extra drag and inefficiency with less idle economy. Minor deviations can occur due to temperature, altitude, or engine wear, but the nominal value is around 1,025 RPM per the operating handbook.