How can adverse weather impact APU performance?

The impact of extreme cold on APU performance is significant due to various factors. Cold temperatures can lead to fuel and oil becoming more viscous, which negatively affects the start-up process of the APU. When the APU is cold, the systems may struggle to reach the required operating temperatures, causing slower response times and potentially leading to incomplete combustion during start-up. This can result in insufficient power output or even failure to start altogether.

Additionally, extreme cold can affect the batteries that supply the initial power required for the APU start-up. Low temperatures can reduce battery efficiency and capacity, making it more challenging to engage the APU's starter motor. Overall, these issues highlight how extreme cold can directly hinder both the start-up and operational efficiency of the APU, resulting in increased reliance on ground power or delayed aircraft operations.