B737 NG
Anti‐Ice & Rain
Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Introduction Thermal anti-icing (TAI), electrical anti-icing, and windshield wipers are the systems provided for ice and rain protection. The anti-ice and rain systems include: • Flight Deck Window Heat • Windshield Wipers • Probe and Sensor Heat
• Engine Anti-Ice System • Wing Anti-Ice System • Ice Detection System [Option]
Anti-Ice Components Diagram [Option - Ice detector probe]
ELEVATOR PITOT PROBES (2 PLACES)
FLIGHT DECK WINDOWS WINDOW HEAT WINDSHIELD WIPERS
TEMPERATURE PROBE ICE DETECTOR PROBE ALPHA VANES (2 PLACES)
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ENGINE COWL LIP
LEADING EDGE SLAT
Boeing B737 NG - Systems Summary [Anti Ice & Rain]
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Flight Deck Window Heat [Option – Window # 3 not heated] Flight deck window numbers 1, 2, 4 and 5 consist of glass panes laminated to each side of a vinyl core. Flight deck window number 4 has an additional vinyl layer and acrylic sheet laminated to the inside surface. Flight deck window number 3 consists of two acrylic panes separated by an air space. [Option – Window # 3 not heated] A conductive coating on the outer glass pane of window numbers 1 and 2 permits electrical heating to prevent ice build–up and fogging. A conductive coating on the inner glass pane of window numbers 4 and 5 permits electrical heating to prevent fogging. Window number 3 is not electrically heated. [Option – Window # 3 heated] Flight deck windows consist of glass panes laminated to each side of a vinyl core. Flight deck window number 4 has an additional vinyl layer and acrylic sheet laminated to the inside surface. [Option – Window # 3 heated] A conductive coating on the outer glass pane of window numbers 1 and 2 permits electrical heating to prevent ice build–up and fogging. A conductive coating on the inner glass pane of window numbers 3, 4 and 5 permits electrical heating to prevent fogging.
Flight Deck Window Heat Operation [Option – Window # 3 not heated] The FWD WINDOW HEAT switches control heat to window No. 1. The SIDE WINDOW HEAT switches control heat to window number 2, 4, and 5. [Option – Window # 3 not heated] Temperature controllers maintain window numbers 1 and 2 at the correct temperature to ensure maximum strength of the windows in the event of bird impact. Power to window numbers 1 and 2 is automatically removed if an overheat condition is detected. A thermal switch located on window 5 opens and closes to maintain the correct temperature of window numbers 4 and 5. [Option – Window # 3 heated] The FWD WINDOW HEAT switches control heat to window number 1. The SIDE WINDOW HEAT switches control heat to window numbers 2, 3, 4 and 5.
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
[Option – Window # 3 heated] Temperature controllers maintain windows numbers 1 and 2 at the correct temperature to ensure maximum strength of the windows in the event of bird impact. Power to window numbers 1 and 2 is automatically removed if an overheat condition is detected. Thermal switches, located on window numbers 3 and 5, open and close to maintain the correct temperature of window numbers 3, 4, and 5.
Flight Deck Window Heat Schematic [Option –Window # 3 heated and green ON lights]
OVERHEAT ON
ON
SIDE
ON
WINDOW HEAT
L OFF
OVHT
FWD
PWR TEST
ON
TEMP CONT
TEMPERATURE CONTROLLER
R
FWD
OFF
SIDE
ON
TEMP CONT
TEMPERATURE CONTROLLER
THERMAL SWITCH
L5
L3
R4
L4
L1
L2 WIND SHIELD AIR
R5
R1
FROM AIR CONDITIONING SYSTEM
R2
R3
WIND SHIELD AIR CONDITION: WINDOW HEAT ON R SIDE OVERHEATED
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
[Option –Window # 3 not heated and amber OFF lights]
OVERHEAT OFF
WINDOW HEAT
L SIDE
OFF
FWD
R
FWD
PWR TEST
ON
TEMP CONT
TEMPERATURE CONTROLLER
OVHT
OFF
SIDE
ON
TEMP CONT
TEMPERATURE CONTROLLER
THERMAL SWITCH
L3
R4
L4
L5
L1
L2 WIND SHIELD AIR
R5
R1
FROM AIR CONDITIONING SYSTEM
R2
R3
WIND SHIELD AIR CONDITION: WINDOW HEAT ON R SIDE OVERHEATED
Windshield Wipers The rain removal system for the forward windows consists of windshield wipers and a permanent rain repellent coating on the windows. CAUTION: Windshield scratching will occur if the windshield wipers are operated on a dry windshield.
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Probe and Sensor Heat [Option - Captain’s pitot probe on standby power] Pitot probes, the total air temperature probe and the alpha vanes are electrically heated. Static ports are not heated. When operating on standby power, only the captain’s pitot probe is heated, however, the CAPT PITOT light does not illuminate for a failure. Note: The pitot probe for standby airspeed is not heated when the airplane is on standby power.
Ice Detection System [Option] An advisory only ice detection system detects airplane icing in flight. The system consists of a probe located on the forward left fuselage and advisory lights located on the left forward panel. When the probe senses ice build–up inflight, the ICING light illuminates. When ice has previously been detected and the probe is no longer detecting ice, the ICING light will extinguish and the NO ICE light will illuminate. The ICING light and the NO ICE light do not illuminate simultaneously. Note: Residual ice may remain on the window areas with the NO ICE light illuminated. The ICE DETECTOR light, located on the forward overhead panel, will illuminate if the ice detection system fails. Illumination of the ICE DETECTOR light also illuminates the MASTER CAUTION and ANTI–ICE system annunciator lights.
Engine Anti–Ice System Engine bleed air thermal anti–icing prevents the formation of ice on the engine cowl lip. Engine anti–ice operation is controlled by individual ENG ANTI–ICE switches. The engine anti–ice system may be operated on the ground and in flight.
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Engine Anti–Ice System Operation Each cowl anti–ice valve is electrically controlled and pressure actuated. Positioning the ENG ANTI–ICE switches to ON: • allows engine bleed air to flow through the cowl anti–ice valve for cowl lip anti–icing • sets stall warning logic for icing conditions. Note: Stall warning logic adjusts stick shaker and minimum maneuver speed bars on the airspeed indicator. FMC displayed VREF is not adjusted automatically. Note: Stall warning logic, airspeed indications, and minimum maneuver speeds on the airspeed indicator return to normal when engine anti–ice is positioned OFF if wing anti–ice has not been used in flight. If the cowl anti–ice valve fails to move to the position indicated by the ENG ANTI–ICE switch, the COWL VALVE OPEN light remains illuminated bright blue and an amber TAI indication illuminates on the CDS after a short delay. The amber COWL ANTI–ICE light illuminates due to excessive pressure in the duct leading from the cowl anti–ice valve to the cowl lip.
ENGINE COWL ANTI-ICE (TAI) COWL ANTI-ICE
COWL ANTI-ICE
COWL VALVE COWL VALVE OPEN OPEN
ENG ANTI-ICE OFF ON
1
5th ENGINE BLEED VALVE COWL ANTI-ICE VALVE
2
TO BLEED AIR DUCT
9th MODULATING & SHUTOFF VALVE
BLEED AIR
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
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. Positioning the WING ANTI–ICE switch to ON in flight: • opens both control valves • sets stall warning logic for icing conditions. Note: Stall warning logic adjusts stick shaker and minimum maneuver speed bars on airspeed indications. FMC displayed VREF is not adjusted automatically. Note: Stall warning logic remains set for icing conditions for the remainder of the flight, regardless of subsequent WING ANTI–ICE switch position. Valve position is monitored by the blue VALVE OPEN lights. Duct temperature and thrust setting logic are disabled and have no affect on control valve operation in flight.
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Wing Anti–Ice System Schematic [Option - ICE DETECTOR light]
ICE DETECTOR L VALVE OPEN
R VALVE OPEN
WING ANTI-ICE OFF ON
THRUST LEVERS
ABOVE T.O. WARNING
HIGH TEMP
BELOW T.O. WARNING THERMAL SWITCH
LOW TEMP
GROUND AIR AIR-GROUND SAFETY SENSORS
BLEED AIR DUCT WING ANTI-ICE CONTROL VALVE
LEADING EDGE SLATS
CONDITION: ON THE GROUND WING ANTI-ICE ON ENGINES AT IDLE THRUST DUCT TEMPS LOW
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BLEED AIR
Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Window Heat Panel [Option – Green ON Lights] OVERHEAT OVERHEAT ON
ON
ON
ON
WINDOW HEAT
L SIDE
OVERHEAT OVERHEAT
OVHT
FWD
R
FWD
OFF
SIDE OFF
ON
ON
PWR TEST
FORWARD OVERHEAD PANEL [Option – Amber OFF Lights] OVERHEAT OVERHEAT OFF
OFF
OFF
OFF
WINDOW HEAT
L SIDE
OVERHEAT OVERHEAT
OVHT
FWD
FWD
OFF ON
R SIDE OFF
PWR TEST
ON
FORWARD OVERHEAD PANEL
Window OVERHEAT Lights Illuminated (amber) – overheat condition is detected. Note: OVERHEAT lights also illuminate if electrical power to window(s) is interrupted.
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Window Heat ON Lights [Option – Green ON Lights] Illuminated (green) – window heat is being applied to selected window(s). Extinguished – • switch is OFF, or • an overheat is detected, or • a system failure has occurred • system is at correct temperature. Window Heat OFF Lights [Option – Amber OFF Lights] Illuminated (amber) – • switch is OFF, or • an overheat is detected, or • a system failure has occurred • system is at correct temperature. Extinguished – window heat is being applied to selected window(s). WINDOW HEAT Switches ON – window heat is applied to selected window(s). OFF – window heat not in use. WINDOW HEAT Test Switch (spring–loaded to neutral) OVHT – simulates an overheat condition. PWR TEST – provides a confidence test. Note: Refer to Supplementary Normal Procedures for Window Heat Test procedures.
Windshield/Foot Air Controls
FOOT AIR
WIND SHIELD AIR
WIND SHIELD AIR
BELOW CAPTAIN’S INST PANEL
FOOT AIR
BELOW F/O’S INST PANEL Page 12
Boeing B737 NG - Systems Summary [Anti Ice & Rain]
FOOT AIR Controls PULL – supplies conditioned air to pilots’ leg positions. WINDSHIELD AIR Controls PULL – supplies conditioned air to number 1 windows for defogging.
Windshield Wiper Selector Panel L WIPER PARK
R WIPER PARK
INT
INT
LOW
LOW
HIGH
HIGH
FORWARD OVERHEAD PANEL Windshield WIPER Selectors PARK – turns off wiper motors and stows wiper blades. INT – seven second intermittent operation. LOW – low speed operation. HIGH – high speed operation.
Probe Heat Panel [Option - Aspirated TAT] CAPT PITOT L ELEV PITOT L ALPHA VANE TEMP PROBE
A
PROBE OFF
B
ON
HEAT TAT TEST
F/O PITOT R ELEV PITOT R ALPHA VANE AUX PITOT
FORWARD OVERHEAD PANEL
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Probe Heat Lights Illuminated (amber) – related probe not heated. Note: If operating on standby power, probe heat lights do not indicate system status. PROBE HEAT Switches ON – power is supplied to heat related system. OFF – power off. TAT TEST Switch [Option - Aspirated TAT] Push - Electrical power applied to TEMP PROBE on the ground.
Engine Anti–Ice Panel
COWL ANTI-ICE
COWL ANTI-ICE
COWL VALVE COWL VALVE OPEN OPEN
ENG ANTI-ICE OFF ON
1
2
FORWARD OVERHEAD PANEL COWL ANTI–ICE Lights Illuminated (amber) – indicates an overpressure condition in duct downstream of engine cowl anti–ice valve. COWL VALVE OPEN Lights Illuminated (blue) – • bright – related cowl anti–ice valve is in transit, or, cowl anti–ice valve position disagrees with related ENGINE ANTI–ICE switch position • dim – related cowl anti–ice valve is open (switch ON). Extinguished – related cowl anti–ice valve is closed (switch OFF). Page 14
Boeing B737 NG - Systems Summary [Anti Ice & Rain]
ENGINE ANTI–ICE Switches ON – • related engine anti–ice valve is open • stick shaker logic is set for icing conditions. OFF – • related engine anti–ice valve is closed • stick shaker logic returns to normal if wing anti–ice has not been used in flight.
Thermal Anti–Ice Indication TAI 8
TAI
87.7
10
0
6
4
87.7
10 8
2 N
1
0
6
4
2
UPPER DISPLAY UNIT Thermal Anti–Ice Indications Illuminated – • Green – cowl anti–ice valve(s) open • Amber – cowl anti–ice valve is not in position indicated by related engine anti–ice switch.
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Boeing B737 NG - Systems Summary [Anti Ice & Rain]
Wing Anti–Ice Panel [Option - ICE DETECTOR System]
ICE DETECTOR L VALVE OPEN
R VALVE OPEN
WING ANTI-ICE OFF ON
FORWARD OVERHEAD PANEL Wing Anti–Ice VALVE OPEN Lights Illuminated (blue) – • bright – related wing anti–ice control valve is in transit, or, related wing anti–ice control valve position disagrees with WING ANTI–ICE switch position • dim – related wing anti–ice control valve is open (switch ON). Extinguished – related wing anti–ice control valve is closed (switch OFF). 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 takeoff warning setting and temperature inside both distribution ducts is below thermal switch activation temperature • control valves close if either engine thrust is above takeoff warning setting or thermal switch is activated in either distribution duct. Switch remains ON • switch trips OFF at lift–off. Page 16
Boeing B737 NG - Systems Summary [Anti Ice & Rain]
ICE DETECTOR Light [Option - ICE DETECTOR System] Illuminated (amber) – Ice detector system has failed.
Icing Advisory Lights [Option - Icing Detector System] ICING P-CANCEL NO ICE P-CANCEL
LEFT FORWARD PANEL ICING Light Illuminated (amber) – • ice detector is detecting ice • light is inhibited on the ground. Press – extinguishes light, if illuminated. NO ICE Light Illuminated (white) – • ice detector is not detecting ice, and the ice detector probe had previously detected ice • light is inhibited on the ground. Press – extinguishes light, if illuminated.
Limitations Engine TAI must be on when icing conditions exist or are anticipated, except during climb and cruise below -40°C SAT. [Option - 737-600/-700/-800 without stiffened elevator tabs] (PRR 38506 or Service Bulletin 737-55A1080) After any ground deicing/anti-icing of the horizontal stabilizer using Type II or Type IV fluids, airspeed must be limited to 270 KIAS until the crew has been informed that applicable maintenance procedures have been accomplished that would allow exceedance of 270 KIAS. Once the applicable maintenance procedures have been accomplished, exceeding 270 KIAS is permissible only until the next application of Type II or Type IV deicing/anti-icing fluids. Page 17
