Ryanair Conversion 4 Practice Test

Conditioned air for cabin pressurization and climate control comes from bleed air that is taken from the engine compressor stages (and sometimes the APU). This hot, high-pressure air is routed to the environmental control system packs, where it’s cooled, and sometimes humidified or mixed with recirculated cabin air, before being supplied to the cabin. The system uses an outflow valve to regulate cabin pressure, while the conditioned air maintains a comfortable temperature inside.

Electrical systems provide power and may drive heaters or electric air-processing equipment in some designs, but they do not supply the primary conditioned air needed for pressurization. Hydraulic systems power various aircraft components, and the fuel system carries fuel; neither is responsible for conditioned cabin air.