Gulfstream G550 Fire Protection System Comprehensive Guide

Fire Protection System Overview

  • The Fire Protection System for the Gulfstream G550 is designed to:
    • Detect the presence of fire or smoke through specialized sensors.
    • Alert the flight crew with both aural and visual warnings regarding fire/smoke presence.
    • Distribute fire extinguishing agents, allowing for manual or automatic discharge, to protected aircraft areas.
    • Evacuate accumulated smoke from the aircraft interior, creating a safer environment and preventing re-entry into the cabin.
Component Details
Smoke Detection System
  • Location: Baggage compartment.
  • Functionality: Operates when the Left Essential DC bus is powered, ensuring readiness even during certain electrical failures or single-engine operations.
  • Smoke Detector Test Switch: Found in the system test panel on the Cockpit Overhead Panel (COP). When activated, it simulates a smoke condition to test the detector and associated alerts, typically resulting in a "BAGGAGE SMOKE" CAS message.
Emergency Smoke Evacuation Valve
  • Location: Above the interior access door to the baggage compartment.
  • Purpose: Allows for the depressurization of the baggage compartment’s exterior door seal during significant differential pressure situations, to prevent residual smoke from re-entering the cabin and to facilitate smoke removal. This action helps to create a negative pressure differential, drawing smoke out.
    • If the interior baggage compartment door is open, cabin air will flow to the baggage compartment and then overboard.
    • If the interior baggage compartment door is closed, airflow to the baggage compartment ceases when the valve is opened.
  • Reset Switch: After the smoke evacuation procedure is complete, this switch allows manual reintroduction of bleed air to repressurize the baggage compartment.
Engine Fire Detection System
  • Each engine is equipped with:
    • Two fire loops labeled as LOOP A and LOOP B.
    • Composed of temperature-sensitive materials arranged like wire, these loops detect fire by continuously monitoring ambient temperature and reporting changes (e.g., resistance drop due to overheating) to the Engine's Fire Detector Control Unit (FDCU).
    • Warning System: The FDCU continuously monitors both loops for integrity and fire conditions. It determines the condition of each loop (failed, fault present, sensing fire) and appropriately alerts the flight crew through Master Warning lights and specific "L/R ENG FIRE" CAS messages.
    • Loop failure handling: Crew can deselect a faulty loop and operate the system with a single loop.
Pylon Overheat Detection System
  • Contains three thermally sensitive switches located adjacent to the bleed air ducting in the pylon area.
  • Warning: If ambient temperature within the pylon exceeds preset levels (typically indicating a bleed air leak or overheating), these thermal switches close, completing a circuit and triggering a "L/R PYLON HOT" CAS message on the Crew Alerting System.
APU Fire Detection System
  • Features: A single helium gas-filled tube runs through the APU system. This tube is designed to differentiate between a general overheat (fault) and an actual fire condition (rapid temperature rise) based on pressure changes within the tube.
  • Warnings: Appropriate alerts, including a Master Warning and "APU FIRE" CAS message, are sent to flight crew if a fire condition is detected. The APU will shut down automatically if a fire is sensed, excluding during testing of the APU Fire Detection System.
Passenger and Tail Compartment Overheat Detection System
  • Thermally sensitive switches are installed throughout passenger and tail compartments that trigger specific CAS messages (e.g., "LEER HT", "AFT FLOOR HT") when excessive temperature is sensed in:
    • Left Electronic Equipment Rack (LEER)
    • Left Aft Floor
    • Right Electronic Equipment Rack (REER)
    • Center Aft Floor
    • Auxiliary Electronic Equipment Rack (AEER)
    • Right Aft Floor
    • Forward Floor
    • Aft Equipment Area (tail compartment)
Fire Extinguishing Systems
Engine Fire Extinguishing System
  • System Arms: Activated when either Left or Right Essential DC bus is powered, ensuring critical fire suppression capability is available even if one main DC bus fails.
  • Fire Extinguishing Bottles:
    • Two identical "single-shot" bottles named LEFT (#2) and RIGHT (#1) containing Halon under high pressure.
    • Discharge: Can be manually triggered by crew using fire handles on the COP, or automatically via a fusible plug designed to rupture and discharge the agent if exposed to extreme temperatures.
    • CAS Message: A low-pressure switch in each bottle triggers a "L/R ENG FIRE BTL LO" CAS message following any discharge (manual or thermal) or if bottle pressure drops below a safe operating level.
APU Fire Extinguishing System
  • Power Source: Left Essential DC bus (non-functional if unpowered), highlighting its critical reliance on this specific bus.
  • Discharge Procedure: The LEFT bottle (#2) is exclusively routed to the APU compartment for APU fires. Once discharged (either manually or automatically during an APU fire on the ground), the agent from this bottle is completely expended and it is no longer available for engine fire extinguishment.
Portable Fire Extinguishing System
  • Contains two extinguishers:
    • Locations: Typically located in the cockpit and cabin for easy access. One with Halon (e.g., Halon 1211 typically located in the cockpit) for Class B and C fires, as well as limited Class A fires.
    • One with water (e.g., located in the cabin) specifically for Class A fires (combustible materials like fabric, wood, paper).
Lavatory Fire Extinguishers
  • Each trash bin features an integrated fire extinguishing unit mounted over it.
System Testing and Alerts
  • Smoke Detection System Test Switchlight:
    • Function: Tests the smoke detector in the baggage compartment by engaging a momentary contact switchlight on the COP. When activated, it simulates a smoke condition at the detector, triggering a "BAGGAGE SMOKE" CAS message and providing indication of system readiness, but without introducing actual smoke into the compartment.
  • Equipment Overheat Test Switchlight:
    • Controls tests for Passenger and Tail Compartment Overheat Detection System, and Pylon Overheat Detection System. When activated, it simulates an overheat condition in each zone, triggering specific CAS messages (e.g., "LEER HT", "L PYLON HOT") for each tested area, confirming sensor and alert system functionality.
Control Panels and Switches
Fire Test and Detection Panel
  • Features various test switchlights for different components:
    • APU Fire Test Switchlight tests the APU Fire Detection System.
    • Engine Fire Test Switchlights test the fire detection systems for each engine (Left and Right).
    • All tests yield specific warning indications, including illumination of Master Warning lights and associated CAS messages (e.g., "L ENG FIRE" for engine tests, "APU FIRE" for APU tests). Crucially, engine fire tests do not emit an audible fire alarm, unlike APU tests which signal an exterior aural warning for on-ground APU fire tests, indicating a potential real-world concern to ground personnel.
Fire Detection Fault Test Switchlight
  • Tests the Fire Detection Fault System. When engaged:
    • When engaged, it illuminates "FAULT" captions on the respective engine fire detection switchlights and triggers a "FIRE DETECT FAULT" CAS message, indicating the fault detection circuitry is operational.
Engine Fire Detection Switchlights (Left Engine Loop A and Loop B)
  • Each switchlight controls respective engine fire detection loops, allowing a single loop to be deselected if a fault is detected (preventing nuisance warnings) or for testing purposes. "FAULT" and "OFF" captions illuminate under specific conditions (fault detected or successful tests of the switchlight functionality), providing clear status indications to the crew.
Operational Procedures
Fire Protection System Normal Operations
  • Normal functioning restricted to preflight tests as defined in the OM Functional Checks tab (chapters 01-10-60 and 01-10-110) and AFM Normal tab for “APU Ground Operation”.
Abnormal and Emergency Operations
  • Covered in AFM Quick Reference Procedures tab under “Fire/Overheat/Smoke”.
  • Engine fire scenarios addressed in AFM Messages and Annunciations tab.
Limitations
  • The Fire Protection System has no established limitations on its operation.