Which of the following items is NOT found on the hot battery bus?

The correct answer is the brake system because it is typically not connected to the hot battery bus. The hot battery bus is designed to supply power to essential components even when the aircraft is not in operation, enabling access to certain systems immediately after an emergency or during specific operations. This includes critical items like the battery switch, emergency flaps, and the emergency locator transmitter (ELT), which require power independently of the aircraft's operational state.

In contrast, the brake system operates as part of the aircraft's overall hydraulic and electrical systems but does not draw power from the hot battery bus. Instead, the brake system relies on different electrical sources that are activated when the aircraft is powered on and operational. This distinction highlights the specific function and operational priority of each system within the aircraft's design.