Why is it crucial to monitor the GPU voltage during start procedures?

Monitoring the GPU (Ground Power Unit) voltage during start procedures is crucial to avoid electrical failure. The GPU provides the necessary electrical power to start the aircraft's engines, especially when they are not yet generating electricity themselves. If the voltage falls below the required level, it can lead to insufficient power for the starter or other critical systems. This may result in a failure to start the aircraft or cause damage to electrical components, hindering the operation of essential systems. Maintaining proper voltage ensures that all electrical components receive the power they need to function reliably during the critical startup phase.

Considering the other options, cabin comfort, engine overheat, and fuel efficiency are not directly affected by monitoring the GPU voltage during start procedures. While those factors are important in overall flight operations, they do not directly relate to the immediate risk of electrical failure that can hinder engine start and operational readiness.