Which components drive cabin conditioning on the 787 when bleed air is not used?

Which components drive cabin conditioning on the 787 when bleed air is not used?

• A. Electrically driven environmental control components (electric air cycle machines)
• B. Bleed air from engines
• C. Hydraulic pumps
• D. APU bleed

Answer: (A)

The main idea being tested is that the 787 uses an all-electric environmental control system, so cabin conditioning is driven by electrically powered components rather than by bleed air. In a bleedless design, electrically driven environmental control components—the electric air cycle machines—handle the cooling, conditioning, and distribution of cabin air. These machines are powered by the aircraft’s electrical system and use closed-loop air cycles with heat exchangers to remove heat and, when needed, provide conditioning without drawing bleed air from engines or the APU. So, the cabin conditioning is achieved through the electric air cycle machines and related electrically driven ECS hardware, rather than from engine bleed air, hydraulic pumps, or APU bleed. This is what makes the 787’s approach distinct and compatible with a bleedless architecture.

The main idea being tested is that the 787 uses an all-electric environmental control system, so cabin conditioning is driven by electrically powered components rather than by bleed air. In a bleedless design, electrically driven environmental control components—the electric air cycle machines—handle the cooling, conditioning, and distribution of cabin air. These machines are powered by the aircraft’s electrical system and use closed-loop air cycles with heat exchangers to remove heat and, when needed, provide conditioning without drawing bleed air from engines or the APU.

So, the cabin conditioning is achieved through the electric air cycle machines and related electrically driven ECS hardware, rather than from engine bleed air, hydraulic pumps, or APU bleed. This is what makes the 787’s approach distinct and compatible with a bleedless architecture.