How does the Propeller Interface Unit (PIU) adjust the propeller pitch?

The Propeller Interface Unit (PIU) adjusts the propeller pitch primarily by varying the amount of oil pressure sent to the propeller. This process is crucial for managing the performance characteristics of the aircraft. The PIU regulates oil flow to the propeller governor, which in turn adjusts the blade angle of the propeller. When oil pressure is increased, it pushes the blades into a finer pitch (for increased RPM), while a reduction in oil pressure allows the blades to adopt a coarser pitch (for lower RPM). This automated adjustment according to flight conditions helps optimize the engine performance, fuel efficiency, and overall safety during operation. Understanding this mechanism is vital for pilots, as it directly impacts the aircraft's climb rate, fuel consumption, and response to throttle inputs.