Which are the three distinct segments of bleed-air ducting?

• A. Engine bleed-air manifolds
• B. Crosswing manifold or main section
• C. Branch ducting
• D. All of the above

Answer: (D)

Bleed-air ducting has three distinct segments: engine bleed-air manifolds, the crosswing or main duct that carries bleed air from the engines toward the distribution system, and branch ducting that splits off to feed individual systems such as packs, cabin pressurization, and anti-ice. The manifolds are where air is taken from compressor stages and introduced into the duct system. The crosswing/main duct acts as the central conduit for that air, delivering it toward the areas that need it. The branch ducts then route the air to specific subsystems. Since each segment represents a different part of delivering bleed air from source to final use, all three are involved, making the all-of-the-above option correct.