What should be done if experiencing uncommanded propeller feather?

In the case of experiencing uncommanded propeller feathering, it is essential to take immediate action to mitigate the risk of loss of control or engine failure. Turning off the PMU (Propulsion Management Unit) switch is the recommended action because it allows you to regain control over the propeller by bypassing the automated control system that may be malfunctioning. When the PMU is turned off, the control reverts to the pilot, allowing for manual management of the engine and propeller settings.

In this situation, the pilot must focus on regaining control of the aircraft. The PMU can sometimes cause undesirable propeller responses due to a malfunction, so disabling it can help improve the situation by restoring manual control, which is critical for safety and aircraft handling.

The other options, such as leaving the PMU on or turning off all electrical systems, do not address the immediate issue and could potentially complicate the situation further. Checking fuel levels also does not directly respond to the uncommanded feathering, as it pertains to a different aspect of aircraft management that is not immediately relevant to propeller control issues.