Which term refers to either the left bleed duct or the right bleed duct in the airplane's pneumatic system?

• A. L bleed duct or R bleed duct
• B. Primary bleed duct
• C. Central bleed line
• D. Aft bleed line

Answer: (A)

Bleed air comes from the engines and travels through dedicated ducts. There are two such ducts, one tied to the left engine and one to the right engine. When you need a term that covers either of these lines, the natural labels are L bleed duct or R bleed duct, indicating which engine’s bleed air is being used. This makes it clear there are two separate ducts feeding the system and avoids implying a single central path. The other terms don’t fit as the standard way to name the side-specific lines: a central bleed line suggests a single shared path, while aft bleed line isn’t the typical designation for these ducts, and primary bleed duct refers to a main source rather than the left/right pairing.