What happens to the hydraulic SOVs when the ENG FIRE switch is activated?

When the ENG FIRE switch is activated, the hydraulic Shutoff Valves (SOVs) close immediately as part of the aircraft's fire protection system. This action is critical for limiting the potential spread of fire and reducing the risk of damage to the hydraulic systems. By closing these valves, the system effectively isolates the hydraulic fluid supply to the affected engine, which helps contain the fire and protect the integrity of the aircraft.

The immediate closure of the hydraulic SOVs is a safety measure that responds directly to the emergency situation posed by an engine fire, enabling the crew to focus on emergency procedures and managing the aircraft. This proactive response is designed to enhance safety by preventing further complications that could arise from hydraulic fluid being exposed to flames or high temperatures.