What is the main purpose of the Precheck Selector Valves?

The primary purpose of the Precheck Selector Valves lies in ensuring the proper operation of the fuel system’s valves within the aircraft. These valves play a critical role in managing fuel flows to various systems, including the engines. By verifying that these valves are functioning correctly before operation or refueling, the Precheck Selector Valves help maintain system integrity and safety.

When functioning properly, these valves facilitate the controlled distribution of fuel from tanks to engines, which is crucial for optimal engine performance and safety during flight operations. Ensuring their operation mitigates the risks of fuel mismanagement, which could lead to potentially severe operational issues.

In the context of the other choices, while regulating fuel pressure, checking fuel level, and initiating refueling are important aspects of fuel management, they do not directly pertain to the predefined function of the Precheck Selector Valves. Their role is specifically tied to the verification and maintenance of valve operability, making option C the most accurate representation of their purpose.