An uncommanded power change is generally the result of which malfunctioning unit?

An uncommanded power change typically arises from issues related to the Power Management Unit (PMU). The PMU is responsible for regulating engine power and ensuring that the fuel flow and power output are appropriately controlled in response to pilot inputs. When the PMU malfunctions, it can misinterpret or fail to execute commands, leading to unintended variations in power output.

This malfunction can manifest as uncommanded increases or decreases in engine thrust, which can substantially affect flight safety and performance. Pilots often have to be vigilant about power settings, and understanding the role of the PMU is crucial for diagnosing and managing power-related issues. The other units mentioned, while important to aircraft functionality, relate to different systems: the Fuel Management Unit focuses on fuel distribution, the Propeller Interface Unit deals with propeller control, and the Control Surface Unit manages the aircraft's control surfaces. Thus, they are less directly related to power management concerns.