General Authority of Civil Aviation (GACA) Aeronautical Information Publication (AIP) Practice Exam

Which parts of the airplane are heated by bleed air?

1. Cockpit windows and wing let

2. Engine inlets and wing leading edges

3. All probes and engine nacelles

4. Horizon indicators and altimeters

The correct answer is: Engine inlets and wing leading edges

The correct choice focuses on the specific functions of bleed air within an aircraft systems framework. Bleed air, which is air taken from the compressor stage of an engine, is commonly used for various heating and pressurization purposes. In this case, heating of the engine inlets and wing leading edges is critical, particularly to prevent ice formation and to ensure aerodynamic efficiency. Ice can accumulate on these surfaces during flight, especially in cold, moist conditions; thus, utilizing hot bleed air to maintain these areas free of ice is vital for flight safety and performance. Heating cockpit windows and winglets, while potentially part of other systems, is not primarily achieved through the bleed air mechanisms. Similarly, while probes and engine nacelles may need some form of heating, they are typically managed by different systems. Horizon indicators and altimeters do not require heating from bleed air, as their functioning is based on pressure and attitude sensing rather than temperature control. This reflects how the correct answer emphasizes the specific applications of bleed air in maintaining critical airfoil performance and engine efficiency.