What is the primary function of the Emergency Power Unit?

The primary function of the Emergency Power Unit (EPU) is to provide hydraulic and electrical power in situations where there may be a failure of the main systems. This ensures that critical systems remain operational despite the loss of primary power. The EPU serves as a backup source of energy, enabling necessary functions such as lowering the landing gear, controlling the flight controls, and maintaining some level of avionics operation.

While the other options may suggest functions related to aircraft systems, they do not align with the specific role of the EPU. The EPU is not designed to provide thrust during takeoff, control cabin pressure, or directly power the landing gear system; rather, it supports systems that include those functions when primary power sources are compromised. Understanding the operational independence provided by the EPU helps pilots manage emergencies effectively and maintain aircraft control in critical situations.