OPERATIONS MANUAL

Ice & Rain Protection
System Overview:
Ice detection
(Normally, installed on just some aircraft; and if installed, it is either a single
or a dual probe system. In the simulator, all aircraft are equipped with a
dual probe system.) Two ice detector probes are installed externally on the
forward fuselage; one on the left, and one on the right side. The tip of each
probe vibrates at 40 kHz by magnetostrictive effects, driven by an electric
coil. When ice builds up on the tip, the frequency decreases. When the
frequency has dropped to a certain limit, a heater activates and melts the
ice. When the frequency has returned to 40 kHz, the heater deactivates
and allows the tip to build up ice again. These cycles are repeated as long
as icing conditions exist, and the system counts these cycles. In non-severe
icing conditions, the heater will melt the ice in circa 10 seconds. In severe
icing, the melting process will take more than 15 seconds; such long cycles
will be counted as 2 cycles. Automatic anti-ice on the nacelles activates after
2 counted cycles, and that on the wings after 10, provided the respective
automatic control is installed and enabled. When the tip has been vibrating
at 40 kHz for 3 minutes, the counter is reset to zero, and all automatic antiice
operation is terminated. When the aircraft is on the ground, the system
will cycle also and melt the ice on the tip, but the counter will be locked at
zero to prevent automatic anti-ice activation on the ground.
Probe heat
The aircraft is equipped with 2 total air temperature (TAT), 4 pitot-static
(P/S), and 2 angle of attack (AOA) probes; engine specific probes are
installed in the nacelles. All probes are electrically heated to prevent ice
formation. There are no flight deck controls for probe heat aside from circuit
breakers. Heat for the TAT probe is automatically activated when in flight.
Heat for P/S, AOA, and engine internal probes is automatically activated
when any engine is running in flight or on the ground.
Water line and waste drain heat
Electric heaters powered by 115 V AC protect all water systems on the
aircraft against icing.
Windows
All flight deck windows are fitted with interior anti-fog systems. The forward
windows also include exterior anti-fog and anti-ice systems. All systems use
electric heat which is automatically modulated. The side window systems are
powered whenever AC power is available; the front window systems require
the WINDOW HEAT switches on the overhead panel to be set to ON.—The
pilots can activate windshield defogging air by switches on the auxiliary
panels (in the simulator not shown).—Controls for windshield wipers and
washers are available on the overhead panel.
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