B737 Anti-ice Panel

Anti-ice Panel
P5 FWD OVERHEAD

ENG ANTI–ICE Lights

  • Illuminated (amber):
    • Indicates the cowl thermal anti-ice system has been inhibited due to a system failure.
    • Indicates an engine core anti-ice valve has failed closed.

COWL ANTI–ICE Lights

  • Illuminated (amber): Indicates an overpressure condition in the duct downstream of the engine cowl anti-ice valve.

COWL VALVE Lights

  • Illuminated (amber):
    • Momentary: Related cowl anti-ice valve is in transit.
    • Steady: Cowl anti-ice valve position disagrees with the related ENGINE ANTI–ICE switch position.
  • Extinguished:
    • Related cowl anti-ice valve is closed (switch OFF), or
    • Related cowl anti-ice valve is open (switch ON).

ENGINE ANTI–ICE Switches

  • ON:
    • Related cowl anti-ice valve is open.
    • Stick shaker logic is set for icing conditions.
    • Green TAI indication shows on the engine display.
  • OFF:
    • Related cowl anti-ice valve is closed.
    • Stick shaker logic returns to normal if wing anti-ice has not been used in flight.
    • Green TAI indication on the engine display extinguishes.

Thermal Anti–Ice Indications

  • Illuminated: “TAI” indication on Engine Display
    • Green: Cowl anti-ice valve(s) are open.
    • Amber: Cowl anti-ice valve is not in the position indicated by the related engine anti-ice switch.

Wing VALVE Lights

  • Illuminated (amber):
    • Momentary: Related wing anti-ice valve is in transit.
    • Steady: Wing anti-ice valve position disagrees with the related WING ANTI–ICE switch position.
  • Extinguished:
    • Related wing anti-ice valve is closed (switch OFF), or
    • Related wing anti-ice valve is open (switch ON).

WING ANTI–ICE Switch

  • OFF: Wing anti-ice control valves are closed.
  • ON (in the air):
    • Wing anti-ice control valves are open.
    • Stick shaker logic is set for icing conditions.
    • Note: Stick shaker logic remains set for icing conditions for the remainder of the flight, regardless of subsequent WING ANTI–ICE switch position.
  • ON (on the ground):
    • Wing anti-ice control valves open if:
      • Thrust on both engines is below the takeoff warning setting.
      • Temperature inside both distribution ducts is below thermal switch activation temperature.
    • Control valves close if:
      • Either engine thrust is above the takeoff warning setting, or
      • The thermal switch is activated in either distribution duct.
      • The switch remains ON.
    • Switch trips OFF at lift-off.