What is critical to ensure while monitoring the APU during operation?

Monitoring performance parameters is essential while the Auxiliary Power Unit (APU) is in operation because these parameters provide vital information about the APU’s functionality and efficiency. Key performance metrics include parameters such as voltage output, frequency, oil pressure, and temperature levels. Keeping a close watch on these aspects is crucial to ensure the APU operates within its design specifications, maintaining operational safety and reliability.

If any performance parameters deviate from the standard values, it may indicate underlying issues that could lead to operational failures or inefficiencies. This is particularly important considering the APU's role in providing electrical power and bleed air for starting engines and powering onboard systems when the main engines are not running. Recognizing and addressing any abnormalities in performance parameters promptly can prevent more significant maintenance issues or operational disruptions.