What is the primary function of the APU Dual entry compressor?

• A. To supply compressed air for cabin pressurization
• B. To mix fuel and air for combustion
• C. To provide pneumatic power under varying loads
• D. To compress air for the combustion process

Answer: (D)

The primary function of the APU (Auxiliary Power Unit) Dual entry compressor is to compress air for the combustion process. This is essential for the APU's operation, as it generates the high-pressure air required to support combustion within the APU's combustion chamber. The compression of air plays a vital role in achieving the right air-to-fuel ratio, which is critical for efficient operation and ensuring sufficient combustion pressure.

While there are other functions associated with an APU, such as providing pneumatic power or compressed air for different systems, the main role of the dual entry compressor specifically revolves around compressing air to support the combustion process, making it integral to the engine's startup and auxiliary functions.