What is lost when the AC BUS SHED annunciator is illuminated?

When the AC BUS SHED annunciator illuminates, it indicates that there is a loss of power to certain electrical systems on the aircraft. The Flap Position Indicator is specifically dependent on the availability of AC power, and when this system is shed, the Flap Position Indicator will not function or display its data.

In this context, the Flap Position Indicator is directly affected by the AC electrical system, which is necessary for its operation. Other indicators, such as the Fuel Quantity Indicator or Engine Temperature Indicator, are typically powered by different systems or have backup power sources that allow them to remain operational even when the AC bus is shed. Understanding which instruments depend on specific electrical sources is crucial for effective flight management and responding appropriately to system alerts.