What is the primary requirement for hydraulic lines regarding their diameter?

The primary requirement for hydraulic lines concerning their diameter is that they must provide the required volume and velocity of flow. This is critical because hydraulic systems rely on a specific flow rate and pressure to function effectively. The diameter of the hydraulic line directly influences the ability of the fluid to flow through it; larger diameters allow for increased volume and flow rates, which are essential for the efficient operation of hydraulic systems. Ensuring the correct diameter helps maintain the system's performance, prevent cavitation, and minimize pressure drops, all of which are vital for the safety and reliability of aircraft hydraulic systems.