At what point will the FCMU turn on?

The correct answer is based on the operational design of the Fuel Control Management Unit (FCMU) and its reliance on fuel gauge indicators, which are represented in LCD segments. The FCMU is designed to activate when the fuel level drops to a critical point, which is indicated by a specific number of segments illuminated on the LCD display.

In this instance, the FCMU will turn on when the fuel level reaches 3 LCD segments. This is a built-in safety feature that ensures the aircraft has enough fuel for safe operation and alerts the crew before the fuel level becomes critically low. Such systems are crucial for monitoring fuel status, enabling immediate actions to be taken if fuel levels fall to a predetermined safety threshold. Understanding this operational function is essential for flight safety and effective management during flight operations.