What is the maximum airspeed if the APU door is open and it is NOT running?

What is the maximum airspeed if the APU door is open and it is NOT running?

• A. 200 Knots
• B. 220 Knots
• C. 240 Knots
• D. 260 Knots

Answer: (B)

When the APU intake door is open and the APU isn’t running, you have a large unprotected opening in the aircraft that is exposed to ram air during flight. At higher airspeeds, the dynamic pressure on that opening can stress or even misalign the door, or allow debris to be ingested, so the system and surrounding structure are protected by limiting how fast you can fly in this condition. That safety limit is set at 220 knots, which keeps the door and intake safe from the forces of air entering it when the APU is idle. If you needed more speed, you’d ensure the door is closed or the APU is operating per procedure.

When the APU intake door is open and the APU isn’t running, you have a large unprotected opening in the aircraft that is exposed to ram air during flight. At higher airspeeds, the dynamic pressure on that opening can stress or even misalign the door, or allow debris to be ingested, so the system and surrounding structure are protected by limiting how fast you can fly in this condition. That safety limit is set at 220 knots, which keeps the door and intake safe from the forces of air entering it when the APU is idle. If you needed more speed, you’d ensure the door is closed or the APU is operating per procedure.