What is the purpose of a fuel tank vent system in an aircraft?

The purpose of a fuel tank vent system in an aircraft is to prevent vacuum buildup and allow air to enter the tank as fuel is consumed. As fuel is drawn from the tank for combustion, the volume of fuel decreases, which would create a vacuum if not for the vent system. This vacuum can hinder fuel flow, causing performance issues and potentially leading to dangerous situations during flight. By allowing air to enter the tank, the vent system ensures that fuel can flow freely to the engines, maintaining consistent performance and safe operation. Therefore, this function is critical to the overall safety and efficiency of the aircraft’s fuel system.