In a multiengine fuel system, how many vents are required?

In a multiengine fuel system, having two vents is essential for maintaining proper pressure and preventing vacuum formation within the fuel tanks. Each vent serves to equalize the pressure as fuel is consumed by the engines, allowing air to enter and preventing fuel from being siphoned excessively due to a vacuum. This ensures a consistent fuel flow to the engines and avoids the risk of fuel starvation. The requirement for two vents helps to accommodate the various operational conditions that multiengine aircraft might face, such as changes in altitude and fuel consumption rates, thereby ensuring safe and efficient performance throughout the flight.