Which hydraulic system does the LG AUX EXT system use to extend the landing gear?

The landing gear auxiliary extension system utilizes System 2 for extending the landing gear. This connection allows for a reliable backup method in case the primary hydraulic systems fail or experience a malfunction. System 2 is specifically designed to manage essential functions like this, ensuring there is a dedicated hydraulic source available for landing gear operations.

The other hydraulic systems, while vital for other aircraft functions, do not serve this specific purpose. Alternative systems have different roles and may control other aircraft components such as flight controls, brakes, or thrust reversers, but System 2 is uniquely suited for landing gear actuation and extension, thereby ensuring safety and operational redundancy in critical moments during flight.