For operations above FL410, all of the following must be normal?

For operations above FL410, all of the following must be normal?

• A. both PRESS SOURCE
• B. both ENG BLEED
• C. ECS knob
• D. All of the above

Answer: (D)

At high flight levels, keeping the cabin environment safe relies on a fully functioning environmental control and pressurization system with each part in its normal operating mode. If the pressurization sources aren’t both in normal, you risk losing a reliable path to maintain cabin pressure. If engine bleed air isn’t available from both sides, the ECS may not get enough conditioned air to sustain the required cabin pressure and temperature. And the ECS knob must be in the normal position so the system can automatically regulate cabin altitude, pressure, and temperature. When all three elements are in normal, the aircraft has the redundancy and automatic control needed to safely operate above FL410. That’s why all of the above must be normal.

At high flight levels, keeping the cabin environment safe relies on a fully functioning environmental control and pressurization system with each part in its normal operating mode. If the pressurization sources aren’t both in normal, you risk losing a reliable path to maintain cabin pressure. If engine bleed air isn’t available from both sides, the ECS may not get enough conditioned air to sustain the required cabin pressure and temperature. And the ECS knob must be in the normal position so the system can automatically regulate cabin altitude, pressure, and temperature. When all three elements are in normal, the aircraft has the redundancy and automatic control needed to safely operate above FL410. That’s why all of the above must be normal.