The primary role for the Auxiliary power unit is to kickstart an aircraft's main engine. The most powerful jet engines you can find on commercial planes require a high rotational speed to become ...

In conventional airliners, the Auxiliary Power Unit (APU) is a small additional engine that runs on traditional jet fuel and helps to provide the energy required to power several non-propulsive ...

The APU, or auxiliary power unit aboard an aircraft has a specific purpose, but also a pretty big drawback. Here's what you need to know about it.