What condition would cause the OBIGGS to shut down automatically?

The OBIGGS (Onboard Inert Gas Generation System) is designed to enhance safety by preventing fuel tank explosions through the generation of inert gas. Specific flight conditions can lead to the automatic shutdown of the OBIGGS to protect the aircraft's fuel system and ensure safe operation.

When the throttles are advanced for takeoff, there is a significant increase in fuel flow and engine power, which may necessitate the OBIGGS to shut down as a precautionary measure to maintain fuel integrity under high-stress scenarios.

Additionally, airspeed over 80 knots with the landing gear not being retracted poses an increased risk for the system as the aircraft approaches takeoff performance thresholds while still maintaining its landing configuration. This creates a need for safety protocols, including the potential shutdown of the OBIGGS.

Furthermore, if engines No. 2 or No. 3 are in reverse thrust, it indicates a situation where the aircraft is decelerating rapidly on the ground after landing. This condition could also require the shutdown of the OBIGGS to prevent fuel ignition risks.

Each of these scenarios reflects conditions that elevate operational risk, leading to the automated protective measure of shutting down the OBIGGS to ensure the safety of the aircraft and its fuel