Wing Anti–Ice System
The wing anti–ice system provides protection for the three inboard leading edge
slats by using bleed air. The wing anti–ice system does not include the leading
edge flaps or the outboard leading edge slats. The wing anti–ice control valves are AC
motor–operated. With a valve open, bleed air flows to the three leading edge inboard slats,
and is then exhausted overboard. The wing anti–ice system is effective with the slats in any
position.
Wing Anti–Ice System Operation
On the ground, positioning the WING ANTI–ICE switch ON opens both control
valves if thrust on both engines is below the setting for takeoff warning activation
and the temperature inside both wing distribution ducts is less than the thermal
switch activation temperature. Both valves close if either engine thrust is above the takeoff
warning setting or either temperature sensor senses a duct overtemperature. The valves
automatically reopen if thrust on both engines is reduced and both temperature sensors
are cool. With the air/ground sensor in the ground mode and the WING ANTI–ICE switch
ON, the switch remains in the ON position regardless of control valve position. The WING
ANTI–ICE switch automatically trips OFF at lift–off when the air/ground sensor goes to the
air mode.
