MD-11 Flight Crew Operations Manual
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Ice and Rain Protection -
Description and Operation
Ice.10.7
During normal operation, if an ice signal is transmitted from either the left or right
ice detector controllers, the ICE alert will be displayed if any airfoil or engine
anti-ice switch has not been turned on. As each ice protection system is selected
on, a corresponding alert will be displayed showing status of the respective
ANTI-ICE switch (this is in addition to switch illumination). When all the ice
protection systems have been selected on, the individual alerts are replaced by a
single alert, A-ICE ALL ON.
As the ice protection systems are operating, the sensor probe continuously cycles
through the test for the detection of ice. If during the next cycle no ice is detected,
a NO ICE DETECTED alert appears after the 60 second ICE signal timer has
elapsed. This informs the flight crew that the ice protection systems may be
selected off. This alert will stay on until all of the ice protection systems have been
selected off.
If a single ice detection system fails, the ICE DET SINGLE alert is displayed. This
tells the flight crew that the ice detection system is now an advisory system only
and observation of windshields and window frames is also required to detect icing
conditions. At the same time the fault is detected, the ICE and NO ICE alerts from
the fault controller are inhibited.
If both ice detector systems fail, the ICE DETECTOR FAIL alert informs the
flight crew that observation of windshields and window frames is required to
detect icing conditions. When this alert is displayed the ICE and NO ICE alerts are
inhibited.
If the ESC loses both digital data buses that transmit the ICE, NO ICE, and FAIL
signals to the Display Electronic Units (DEU), an AIR ALERTS alert is displayed.
In this case, the ice detection system cannot be used to determine if the aircraft is
in icing conditions.
Miscellaneous Heating Systems
The forward, center, and aft lower cargo door latch actuators, as well as the
forward and center lower cargo door sill drains, are electrically heated by a system
powered through the 115-volt ac ground service bus.
The potable water system supply lines, drain lines, drains, and fill/drain valves are
electrically heated. The system is powered through the 115-volt ac ground service
bus. The potable water system vent/overflow and aft drain heaters are powered
through the ground service bus by 28 volts dc.
Automatic Anti-Ice Protection System
The ice protection system automatically commands the wing, tail, and engine
cowl anti-ice valves open when either of the two ice detection systems detect ice.
The automatic ice protection system consists of the following:
October 02, 2006
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