ICE PROTECTION Incomplete

ICE PROTECTION Incomplete
ICE PROTECTION
GENERAL
The Ice and Rain Protection Systems allow the aircraft to operate in icing conditions or heavy
rain. Aircraft Ice Protection is provided by heating in critical areas using either:

Hot Air from the Pneumatic System
o
o
o

Wing Leading Edges
Stabilizer Leading Edges
Engine Air Inlets
Electrical power
o
o
o
o
Windshields
Probe Heat
 Pitot Tubes
 Pitot Static Tube
 AOA Sensors
 TAT Probes
Static Ports
 ADC
 Pressurization
Service Nipples
 Lavatory Water Drain
 Potable Water
Rain removal from the Windshields is provided by two fully independent Wiper Systems.
LEADING EDGE THERMAL ANTI ICE SYSTEM
Ice protection for the wing and horizontal stabilizer leading edges and the engine air inlet lips is
ensured by heating these surfaces. Hot air supplied by the Pneumatic System is ducted through
perforated tubes, called Piccolo tubes. Each Piccolo tube is routed along the surface, so that hot
air jets flowing through the perforations heat the surface. Dedicated slots are provided for
exhausting the hot air after the surface has been heated.
Each subsystem has a pressure regulating/shutoff valve (PRSOV) type of Anti-icing valve. An
airflow restrictor limits the airflow rate supplied by the Pneumatic System. The systems are
regulated for proper pressure and airflow rate. Differential pressure switches and low pressure
switches monitor for leakage and low pressures.
Each Wing's Anti Ice System is supplied by its respective side of the Pneumatic System.
The Stabilizer Anti Ice System is supplied by the LEFT side of the Pneumatic System.
The APU cannot provide sufficient hot air for Pneumatic Anti Ice functions.
ENGINE ANTI ICE SYSTEM
Engine Anti Ice is provided by heating the Engine Air Inlet Lip. This Bleed Air comes directly from
the compressor upstream of the High Stage Valve and is independent of the aircraft Pneumatic
System. There is NO temperature control as there is sufficient air flow around the Inlet Lip to
prevent any overheating. There is no limitation for using the EAI System when the aircraft is on
the ground.
ICE DETECTION SYSTEM
Ice accumulation can be seen by the pilots on the Windshield corners and Wiper arm. At night
use the Inspection Lights to illuminate the Wing Leading Edges.
The Ice Detection System is primarily a fully automated system. When in icing conditions it
activates the required Hot Air Protection Systems and configures the Integrated Pneumatic Bleed
System. It also signals the Stall Protection System (SPS) to reduce the AOA Set Trigger Values.
The Ice Detectors 1 and 2 are installed on the airplane's Left and Right Nose section. They are
shaped to quickly detect ice formation. The Ice Detectors will detect ice before the pilot can see
ice form anywhere. 0.5 mm of ice accumulation will trigger the system.
The Detector is a nickel alloy tube mounted on a strut, with one inch exposed to the air stream. It
vibrates ultrasonically. As the Ice Detector enters an ice condition the vibration frequency of the
Probe decreases.
The Ice Detector unit is heated periodically to remove the ice that caused the automatic
response. When the Probe's natural frequency is restored the heating is stopped and it is ready
to detect for ice again. Once de-iced the Ice Detector is cooled enough in a few seconds to begin
detecting for ice once again. Within ice conditions the Ice signal remains active for 60 seconds.
The Ice Detectors remain active in all flight phases. The Ice Detector TEST Switch checks the
system by simulating an ICE CONDITION signal.
EICAS will display a Caution Message if the Anti Ice is ON when outside icing conditions.
ICE DETECTION OVERRIDE KNOB
The system logic corresponding with knob selection is as follows:
ENG
ENGINE
WING and STAB
ON
ON when ICE CONDITION
AUTO
ENGINE
WING and STAB
ON when ICE CONDITION
ON when ICE CONDITION
ALL
ENGINE
WING and STAB
ON
ON
NOTE: WING and STAB inhibited on ground < 25 kts.
The Wing and Horizontal Stabilizer Subsystems are INHIBITED on the ground below 25 knots to
prevent overheating and structural damage.
At American Eagle, when planning an icing takeoff, the Override Knob is selected to ENG so as
to establish an ANT I ICE ON N1 target for the FADECs to achieve. An N1 change that may or
may not occur somewhere in the takeoff roll above 25 knots (due to icing conditions detection) is
not desirable.
To prevent a loss of thrust from the Engines on Takeoff, when the Anti Ice Systems are active,
the FADEC incorporates and automatic Ice Compensation Logic. This is selected on by the MFD
Takeoff Page's REF A-ICE: ON option.
In-flight the FADEC re-establishes idle thrust to satisfy Anti-Ice System needs. This logic is
inhibited when the Landing Gear is DOWN to improve Rate of Descent and Glideslope
compliance.
The Bleed Air Thermal Anti Icing Systems may be individually deactivated by buttons on the
Overhead Panel.
WINDSHIELD HEATING SYSTEM
The Windshields are electrically heated for Anti Icing protection and Anti Fogging prevention. A
conductive film imbedded within its inner layer acting as an electrical resistor.
Left and Right Windshields are individually controlled. There are separate power sources for
each Heating Element and each Control Circuit. Each Heating Element has a dedicated
Temperature Controller that receives a signal from the associated Temperature Sensors. The
control range is: 40°C to 45°C (104 - 113°F). When the Upper Temperature Limit is reached
the power supply is interrupted. When the Lower Temperature Limit is reached the power supply
is restored.
Each Windshield has 3 Temperature Sensors.
 One is used for Temperature Control,
 One is used for Overheat Protection (>55 degrees C)
 One is used as a Maintenance backup in case of failure in the others.
SENSOR HEATING SYSTEM:
All the Sensors and electrically heated and controlled by 3 overhead panel buttons. The aircraft
provides automatic Sensor Heating for:




Pitot Static Tubes,
Pressurization System & ADS Static Ports,
TAT Sensors 1 (2), and
AOA Vanes 1 (2).
In the Automatic Mode the System operates according to 3 Logic sets:
 These are heated whenever one Engine is operating with N2 > 56.4%:
o Pitot 1 and 2,
o Pitot/Static 3,
o AOA 1 and 2,
o ADS Ports 1, 2 ,3, and 4, and
o Pressure Static Ports 1 and 2.
 These are heated in any and all flight conditions,
o Pitot/Static 3,
o Pressurization System Static Port 2
 These are heated provided either Engine 1 or 2 Anti Icing Subsystems are functioning
or the aircraft is in-flight:
o TAT 1
o TAT 2.
Sensor Heat deactivation is accomplished either when the above conditions are NOT met or
when the associated Control Button is manually released.
LAVATORY WATER DRAIN AND NIPPLE HEATING SYSTEM
This system prevents lavatory water from freezing and clogging under all ground and flight
conditions. The aircraft provides automatic DC BUS 1 powered heating for the
 Lavatory Waste Water Drain, and
 Potable Water Service Nipples [Overflow and Fill Nipple
ICE COND-A/I INOP:
Any Bleed Air Thermal Anti Ice Subsystem NOT functioning properly in icing conditions.
NO ICE-A/ICE ON
Any Anti-Icing Valve OPEN, and:
 In-flight, and
 NOT in icing conditions.
A/ICE SWITCH OFF
Any Bleed Air Thermal Anti Ice Button is turned OFF.
E1 (2) A/ICE FAIL OR WG1 (2) A/ICE FAIL OR STAB A/ICE FAIL
 Low Pressure condition
 Valve failure
 Any Switch failure
 Overpressure condition
 Any System activation device failure
WG A/ICE ASYMMETRY
Asymmetrical degradation of the Wing Anti Ice System
W/S 1 (2) HEAT FAIL
 Associated Windshield Heating System failure, < 38°C
 Associated Windshield Overheat condition, > 55°C.
PITOT 1 (2), (3) INOP
Associated Sensor Heating is inoperative.
AOA1 (2) HEAT INOP
Associated Sensor Heating inoperative.
TAT 1 (2) HEAT INOP
Associated Sensor Heating inoperative.
ICE DETECTORS FAIL
Both Ice Detectors have FAILED.
ICE DET 1 (2) FAIL
Respective Ice Detector has FAILED.
ICE CONDITION
Aircraft is flying in ice conditions.
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