If a cooling activation fails on the ground, which valve is implicated?

If a cooling activation fails on the ground, which valve is implicated?

• A. Ground valve
• B. Pack valve
• C. Cabin valve
• D. APU valve

Answer: (A)

Cooling while on the ground relies on opening a path that gates the ground-sourced bleed air to the packs. The ground valve is the element that connects or disconnects that ground cooling path. If cooling activation fails on the ground, the valve that would be responsible for enabling the ground path to the packs is implicated—the ground valve. A fault here would block bleed air to the packs despite the cooling command, so no cooling would occur. The other valves control different parts of the system (pack flow, cabin air distribution, or APU bleed) and would not specifically explain a ground-only cooling failure in the same direct way.

Cooling while on the ground relies on opening a path that gates the ground-sourced bleed air to the packs. The ground valve is the element that connects or disconnects that ground cooling path. If cooling activation fails on the ground, the valve that would be responsible for enabling the ground path to the packs is implicated—the ground valve. A fault here would block bleed air to the packs despite the cooling command, so no cooling would occur. The other valves control different parts of the system (pack flow, cabin air distribution, or APU bleed) and would not specifically explain a ground-only cooling failure in the same direct way.