During high 'G' maneuvers, which of the following actions does a flapper valve specifically assist with?

The correct choice highlights the role of the flapper valve in ensuring proper fuel flow direction, particularly under high 'G' maneuvers. When an aircraft experiences rapid changes in acceleration, such as during tight turns or rapid climbs and descents, the forces can cause fuel to shift within the tank. The flapper valve is designed to prevent fuel from reversing flow, which is crucial for maintaining the intended fuel supply to the engine.

This mechanism is vital because if fuel were to flow backward or become displaced away from the fuel pickup area during these high 'G' conditions, it could lead to fuel starvation at the engine. This might compromise engine performance and could potentially lead to engine failure. Therefore, the flapper valve acts as a safeguard to ensure that fuel remains accessible to the engine even when the aircraft is subjected to extreme maneuvers.