• Reduces the amount of oxygen in the air within the center tank.
  • Fuel Tank Inerting System (FTIS)
    • Conditioned Service Air System (CSAS) – ATA 21
    • Inert Gas Generation System (IGGS)


Hot Bleed Air > CSAS Isolation Valve > Ozone Converter > CSAS Heat Exchanger (TCM) > Conditioned Air

  • CSAS Controller Unit (CCU)
    • Controls CSAS Isolation Valve
    • Interface with IGGS Controller Unit (ICU)
    • Has BITE function of CCU
    • Also has BITE functions of ICU


Conditioned Air > IGGS Isolation Valve > D-ULPA (Double ultra low particle) filter > Air Separation Module > NEA + OEA

  • NEA > Dual Flow Shut Off Valve > Dual Flapper Check Valve > Center Tank
  • OEA discards overboard.
  • Dual Flow Shut Off Valve, two function –
    • Open/Shut for NEA
    • Controls NEA Flows
      • Low – Climb and Cruise
      • Mid – Approach
      • High – Descent
  • IGGS Controller Unit (ICU) – Controls IGGS Isolation Valve
  • Oxygen sensor – measures the oxygen concentration of the NEA.


  • The ozone converter catalytically decreases the ozone concentration of the bleed air. The decreased ozone concentration prevents damage to the air separation module fibers of the inert gas generation system.
  • The CSAS Temperature Control Module (TCM) has:
    • a CSAS heat exchanger,
    • a hot air bypass valve,
    • a temperature sensor,
    • a pressure sensor.
  • TCM is installed on the ram air inlet side of the air conditioning pack 1 heat exchanger.
  • IGGS Pallet – a structural support made of aluminum, contains the isolation valve, D-ULPA filter, ASM, oxygen sensor, and Dual Flow Shut-Off Valve.
  • The fuel tank is inert when the average oxygen concentration is below 12% at sea level.
  • The aircraft crew does not operate the FTIS, because it has automatic control.
  • When the aircraft is on ground the FTIS does not operate.
  • During aircraft flight, the FTIS operates automatically.
  • CSAS is required to cool down hot bleed air at a level compatible with IGGS.


  • CSAS Controller – 1
  • IGGS Controller – 1

Leave a Reply

Your email address will not be published. Required fields are marked *