Where does the air from the engines used for pneumatics come from?

• A. From ram air system in packs.
• B. From the 2nd and 3rd stage bleed.
• C. From the APU bleed only.
• D. From the 6th and 10th stage bleed sections of the N2 compressor.

Answer: (D)

Pneumatic systems on jets get their supply from bleed air drawn directly from the engine compressor. The air must come from specific compressor stages to provide the right pressure and temperature for the systems that use it. In this case, the 6th and 10th stage bleed ports on the N2 compressor are used, because they deliver the appropriate bleed-air pressure for the aircraft’s pneumatics (packs and related systems). Ram air isn’t used as the primary air source for pneumatics, and while APU bleed can supplement when engines aren’t supplying bleed air, the question focuses on air sourced from the engines, making the 6th and 10th stage bleeds the correct source.