'T‑6B Systems 2 Practice Test 2025 – The Complete All-in-One Guide to Exam Success!'

The correct choice hinges on the function of the Propeller Control System in the T-6B, specifically how it regulates propeller speed. The PMU, or Power Management Unit, is responsible for managing engine and propeller performance. It ensures the propeller maintains a constant speed of 2000 RPM by adjusting fuel flow, which in turn affects the propeller's power and RPM.

Complementing the PMU, the propeller interface unit serves to relay information and commands between the PMU and the propeller governor system. Together, they work in tandem to dynamically adjust the propeller's pitch and torque to achieve and maintain the desired RPM.

In contrast, other options like the feathering spring and regulator unit or the torque probe and scavenge unit do not control the RPM directly. The fuel flow regulator and fly weights are involved in regulating fuel and responding to centrifugal forces, but they do not provide the comprehensive control that the PMU and propeller interface unit do. Thus, the PMU and propeller interface unit are integral for maintaining the constant propeller speed of 2000 RPM.