What does the ground valve do?

What does the ground valve do?

• A. It depressurizes the cabin on the ground and increases air flow for avionics cooling.
• B. It maintains cabin pressurization on the ground.
• C. It controls the APU door operation.
• D. It provides air for cabin temperature control.

Answer: (A)

The ground valve is meant to vent the cabin to ambient on the ground and boost ram air flow for avionics cooling. When the aircraft is parked, keeping the cabin pressurized isn’t the goal; instead, the valve opens to equalize with outside pressure and route air through the avionics cooling path, helping keep equipment within its thermal limits while systems are powered but not in flight. This avoids unnecessary cabin pressurization on the ground and provides the needed cooling airflow for avionics, which is why it’s the best description of its function.

The ground valve is meant to vent the cabin to ambient on the ground and boost ram air flow for avionics cooling. When the aircraft is parked, keeping the cabin pressurized isn’t the goal; instead, the valve opens to equalize with outside pressure and route air through the avionics cooling path, helping keep equipment within its thermal limits while systems are powered but not in flight. This avoids unnecessary cabin pressurization on the ground and provides the needed cooling airflow for avionics, which is why it’s the best description of its function.