Which of the following is a component of the APU lubrication system?

The pressure switches are an essential component of the APU (Auxiliary Power Unit) lubrication system. They play a critical role in monitoring the oil pressure within the system to ensure that it operates efficiently and effectively. If the oil pressure drops below a certain threshold, these switches trigger alarms or shutdown sequences to prevent damage to the APU.

In addition to their monitoring function, pressure switches help maintain the proper flow of lubrication oil, which is vital for reducing friction and wear on the moving parts of the APU. Proper lubrication is crucial for the longevity and reliability of the APU, particularly in aviation applications where performance is paramount.

The other options, while integral to the overall functioning of an APU, do not contribute directly to the lubrication system. The fuel control unit manages fuel flow, the compressor drive shaft transmits power, and the air conditioning unit regulates cabin temperature, but none of these directly participate in the lubrication process of the APU. This distinction highlights why pressure switches are the correct choice regarding components specifically associated with lubrication systems.