What is the function of the vented caps on the fuel tanks?

The function of the vented caps on the fuel tanks is primarily to release vacuum pressure. When fuel is drawn from the tank during operation, it creates a reduction in pressure inside the tank. If there were no venting system, this negative pressure could restrict fuel flow or even prevent fuel from being properly delivered to the engine.

The vented caps allow air to enter the tank, equalizing pressure and ensuring a continuous flow of fuel as it is consumed. This is critical during flight, as consistent fuel delivery is necessary for engine operation.

The other options are important in their own ways, but they do not directly relate to the primary role of vented caps. For example, while preventing fuel leakage is essential, it is more about the integrity of the fuel system rather than the specific function of venting caps. Similarly, enhancing fuel delivery pertains more to the design of the fuel system and not the venting itself. Water drainage could be relevant in certain contexts but is not a function of vented caps on fuel tanks.