PA.IX.C.K1b concerns icing in which sub-system?

• A. Carburetor or induction icing.
• B. Wing icing.
• C. Fuselage icing.
• D. Cabin icing.

Answer: (A)

Carburetor or induction icing is the icing issue most closely tied to a sub-system of the engine—the air intake system. When humid air moves through the carburetor, ice can form in the throat or along the induction path, restricting airflow and disturbing the fuel–air mixture. This reduces engine power and can cause rough running or a drop in RPM. The situation is typically seen in conditions with visible moisture and near-freezing temperatures, especially at mid or low power settings. The usual remedy is carburetor heat, which transfers heat to melt the ice and restore normal airflow; if needed, switching to alternate air can help bypass the icing path.

Wing icing, fuselage icing, and cabin icing involve external or internal surfaces rather than the engine’s air intake system. They affect lift or comfort, not the engine’s ability to draw in air and maintain the proper mixture, so they’re not the sub-system related to this specific icing concern.