Private jets require a dedicated source of power to operate systems while on the ground without draining the aircraft's internal batteries. On larger private jets, this is provided by an auxiliary power unit (APU), which is a self-contained jet engine located in the tail of the aircraft. This unit is designed exclusively to generate electrical power and does not contribute to the aircraft's thrust.
Smaller light jets, such as the Phenom 100, do not carry an onboard APU due to their size. Instead, these aircraft utilize a ground power unit (GPU). This external piece of equipment is connected to the aircraft while it is parked to provide the necessary electrical current, ensuring the jet's battery remains charged for departure.
