The fire protection system is divided into the fire detection and fire extinguishing systems.

The fire detection system detects fire in the engines and APU. It also provides overheat detection in the main landing gear bays and smoke detection for the baggage compartment. The detection system uses fire/overheat loops and smoke detectors to alert the flight crew.

The fire extinguishing system provides extinguishing capability for the engines and APU. Fire extinguishing agent is supplied to the engines and the auxiliary power unit (APU) through a distribution system controlled in the flight compartment. The extinguishing system also has a portable fire extinguisher for manual operation in the aircraft.

The ENG/APU fire switches arm the extinguisher bottles, close fuel, bleed air, and hydraulic valves, shut off the generator, and command the engine to shut down. The FIRE EXT switches fire the squib in the associated bottle and direct pressurized Halon into the engine/APU fire zones.

The FIREX control unit (FIREX-CU) monitors and provides indications for the FIREX system. The detection and extinguishing systems are tested and monitored from the flight compartment.

The fire protection system has interfaces with the detection system, the extinguishing system and the fire detection and extinguishing control unit. Also, the control unit has interfaces with the engine indication and crew alerting system (EICAS) and the audio integrating system for visual and audio indication in the flight compartment.