Which engines provide bleed air to the AC packs?

Which engines provide bleed air to the AC packs?

• A. Left engine only
• B. Right engine only
• C. APU only
• D. Both main engines

Answer: (D)

Bleed air to the air conditioning packs comes from the compressor bleed ports on the engines. In twin-engine aircraft, there are two bleed sources—one from each engine—and the environmental control system is designed to use either or both as needed. Through bleed-air valves and cross-bleed capability, the packs can be supplied from both engines, providing adequate flow and redundancy. The APU can supply bleed air in some conditions (such as on the ground or during start) but the question focuses on engines, and the configuration commonly allows the packs to be fed by both main engines.

Bleed air to the air conditioning packs comes from the compressor bleed ports on the engines. In twin-engine aircraft, there are two bleed sources—one from each engine—and the environmental control system is designed to use either or both as needed. Through bleed-air valves and cross-bleed capability, the packs can be supplied from both engines, providing adequate flow and redundancy. The APU can supply bleed air in some conditions (such as on the ground or during start) but the question focuses on engines, and the configuration commonly allows the packs to be fed by both main engines.