What happens to the starter when the engine is able to sustain itself?

When the engine is able to sustain itself, the starter stops its primary function of turning the engine to initiate combustion and instead engages in a secondary role known as "generator mode." In this mode, the starter effectively shifts its operation to support the generation of electrical power, functioning within the aircraft’s electrical system to maintain power to various components.

This transition is crucial because it allows for the continuous supply of electrical energy after the engine has started. The starter does not become non-functional, stop altogether, or operate continuously in its original capacity, as those options overlook the designed functionality of electric starters in the context of engine operations. The designation of “generator mode” reflects the incorporation of the starter into the aircraft's power management system, ensuring it contributes to electrical needs after the engine is running.