What must be ensured before making or breaking a connection between the polyalphaolefin (PAO)/air cooling cart and the aircraft?

Before making or breaking a connection between the polyalphaolefin (PAO)/air cooling cart and the aircraft, it is essential to ensure that the system is depressurized. This step is crucial for safety reasons; handling pressurized systems poses a significant risk, including potential injury from fluid release or other hazardous situations.

Depressurizing the system minimizes these risks, allowing personnel to connect and disconnect the equipment safely. Additionally, ensuring the system is not under pressure helps prevent leaks and spills of the PAO, which could lead to environmental issues or equipment damage.

While other factors such as clearing the area of personnel and ensuring optimal temperature may be important in different contexts of operation, they do not carry the same immediate safety implications as confirming that the system is depressurized. Therefore, the focus on depressurization is paramount in this scenario.