What system is responsible for closing off the flow line to a tank if an imbalance persists?

The Engine Data Manager (EDM) is responsible for monitoring various engine parameters and systems in the T-6B and can detect imbalances in fuel flow. If a persistent imbalance is detected, it is crucial for the EDM to take corrective action to ensure the safety and efficiency of the engine operation. This includes closing off the fuel flow line to the tank, preventing situations that could lead to engine malfunction or failure.

The EDM plays a central role in maintaining the proper operation of the engine by processing data from various sensors and issuing commands based on this information. By closing the flow line in response to a detected imbalance, it helps protect the engine and enhances the overall reliability of the aircraft's systems.

In contrast, while the Fuel Management Unit (FMU) and Fuel Data Manager (FDM) are involved in managing and distributing fuel, and the Control Display Unit (CDU) serves mainly as the interface for the pilot to interact with the aircraft systems, they do not possess the necessary authority or functionality to manage fuel flow in the same way the EDM does. Therefore, the EDM is the correct choice for this question.