What can be deployed as an emergency means of pressurizing the blue hydraulic system?

The Ram Air Turbine (RAT) can be deployed as an emergency means of pressurizing the blue hydraulic system on the A320. The RAT is a critical component that provides emergency power and hydraulic pressure to essential systems when normal sources are unavailable, particularly during an in-flight emergency due to a total loss of power. When extended, the RAT utilizes airflow generated by the forward motion of the aircraft to drive a small hydraulic pump, which then supplies hydraulic pressure to specific systems.

This mechanism is vital during dual engine failure scenarios or situations where both the engine-driven hydraulic pumps are not functioning, ensuring that basic flight controls and landing gear operation can still be maintained. The RAT specifically supports the blue hydraulic system, allowing for continued operation of crucial aircraft systems during emergencies.

The other options do not serve the same function in emergency situations. The PTU is a system designed to assist in transferring hydraulic fluid between systems under normal operational conditions, while the standby electric pump provides hydraulic pressure primarily for the green hydraulic system and would not specifically address the blue hydraulic system needs in an emergency scenario. Saying that no alternate means exist does not apply, as the RAT does provide an emergency backup option.