What happens when the L/R Fuel PESS LO annunciator is triggered?

When the L/R Fuel PESS LO annunciator is triggered, it signifies that the fuel pressure in the respective system has dropped to a low level. In response to this condition, the boost pump is activated automatically. The purpose of the boost pump is to maintain fuel flow and pressure to the engine, providing the necessary fuel supply and ensuring that the engine operates efficiently. This activation helps to prevent engine failure or fuel starvation by compensating for the low pressure situation. The system is designed to react this way as a safety measure, highlighting the importance of maintaining adequate fuel pressure in the aircraft's fuel system.