How do you manually close the HYD SOV?

The correct method to manually close the HYD SOV (Hydraulic Shutoff Valve) is by pressing the ENGINE FIRE PUSH button. This action is designed for emergency situations where immediate closure of the hydraulic systems is necessary to prevent further damage or fuel leakage during an engine fire. The mechanism typically linked to the ENGINE FIRE PUSH button directly influences the closure of the hydraulic shutdown system.

Understanding the rationale behind the other options clarifies why they are not suitable. Merely using the HYD SOV button may not provide the immediate closure required in emergency scenarios, as it typically relies on electrical actuation rather than a direct manual override. Disengaging all hydraulic systems simultaneously would not specifically target the HYD SOV and could introduce complications in managing the aircraft's hydraulic systems. Lastly, stating that manual closure is not possible ignores the designed redundancy and emergency measures integrated into aircraft systems, which include the use of the ENGINE FIRE PUSH button for such critical situations.