What is a possible consequence of a drop in airplane battery voltage during APU start?

A drop in airplane battery voltage during APU start can lead to the activation of ACAWS (Aircraft Condition and Warning System) messages. The ACAWS is designed to monitor various systems and components of the aircraft, and it provides warnings to the flight crew regarding any abnormalities or failures. When the battery voltage drops below certain thresholds during the APU start sequence, it triggers the system to alert the crew of potential issues that could affect performance or system integrity. This alert enhances situational awareness and allows the crew to take necessary actions to mitigate any potential problems that may arise from the voltage drop.

In contrast, the other options describe scenarios that are less directly related to a voltage drop during APU start. For example, engine failures usually stem from other mechanical or operational issues rather than battery voltage drops. Similarly, while fuel system malfunctions can occur under various conditions, they are not commonly caused by battery voltage issues. Lastly, while electrical overloads can indeed occur in aircraft systems, the immediate concern in the context of an APU start and low battery voltage is more about system alerts rather than an overload situation.