Final answer:
Before commencing refueling operations, the refuel high-level shutoff valves should be checked for proper operation to ensure safety and prevent overfilling of the aircraft's fuel tanks.
Step-by-step explanation:
In the context of aviation and aircraft maintenance, the proper operation of refuel high-level shutoff valves is critical during the process known as hot refueling. These valves are designed to prevent overfilling of an aircraft's fuel tanks by automatically shutting off the fuel flow once the tank reaches its capacity.
For safety and operational integrity, these valves should be checked for proper operation before commencing refueling operations. This check ensures that the system will function as intended and will not cause overfilling, which could lead to fuel spillage or other hazardous situations. It is also imperative to follow the aircraft's specific maintenance manual and safety procedures when performing any fuel system checks or operations.