WING ANTI-ICE -FUNCTIONAL DESCRIPTION -ELECTRICAL
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WING ANTI-ICE -OPERATION
General
The wing anti-ice selector lets the flight crew select the operational mode of the system. Indications on the EICAS display and on the air synoptic display show when the WAI valves are open.
Operation
The selector is on the anti-ice/lighting panel (P5). With the selector set to OFF, the WAI system does not operate. The WAI valves stay closed. The EICAS advisory message ICING WING shows if the airplane is in the air and the ice detection system finds ice. The OFF selection prevents the WAI BITE periodic ground test.
For normal operation, the crew keeps the selector in AUTO. The wing anti-ice system operates automatically. The ice detection system controls wing anti-ice system operation as long as operational mode inhibits are not active. The AUTO position enables the BITE periodic ground test.
For manual operation, the crew sets the selector to ON when wing anti-ice is needed. The WAI valves stay open as long as no operational mode inhibits are active. The EICAS advisory message ANTI-ICE ON shows if all of these conditions occur:
*
Airplane is in the air
*
WAI selector is set to on
*
No ice is detected
* TAT is more than 50F (10C).
See the ice detection system for more information about the ice detectors (SECTION 30-81).
Air Synoptic Display
The valve symbols show these conditions:
*
Valve open -white circle with a horizontal green flow bar
*
Valve closed -white circle with two vertical white bars
*
Valve not in commanded position -amber circle with an amber cross through it
*
Valve position data not available -white circle.
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777 AIRCRAFT MAINTENANCE MANUAL
WING ANTI-ICE -OPERATION
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WING ANTI-ICE -SYSTEM TESTS
General
These are the wing anti-ice system tests that show when you select ATA 30 Airfoil Cowl Ice Protection System:
*
Wing anti-ice (pneumatics available)
*
Wing anti-ice (pneumatics not available).
Wing Anti-Ice (Pneumatics Available)
This test makes sure that the wing anti-ice system can control the bleed airflow to each wing.
During the test, hot air flows out of the leading edge on each wing. The test takes approximately 1-2 minutes.
WARNING: DO NOT OPERATE THE WAI SYSTEM UNTIL ALL PERSONS ARE CLEAR OF THE WING LEADING EDGE. THE HOT AIR CAN BURN YOU.
Wing Anti-Ice (Pneumatics Not Available)
This test makes sure that the electrical interface connections of the wing anti-ice system are correct.
The test takes approximately 1-2 minutes.
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777 AIRCRAFT MAINTENANCE MANUAL
WING ANTI-ICE -SYSTEM TESTS
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ENGINE ANTI-ICE -INTRODUCTION
Purpose
The engine anti-ice (EAI) system heats the leading edge of the engine cowls so that ice does not collect on them.
General
The EAI systems for the left and right engines are identical. A high stage bleed port (HP15) on the engine supplies bleed air to heat the cowl leading edge. This is the same stage as the high stage port for the pneumatic system, but the EAI and the pneumatic system use different bleed ports. An engine anti-ice valve controls the air flow from the bleed port to the EAI duct. The EAI duct moves the air to the cowl leading edge. Overboard vents in the cowl let the air out.
The EAI valve is pneumatically actuated. Control pressure for the valve comes from an EAI controller.
ACIPS Control Cards -EAI
Two airfoil and cowl ice protection system (ACIPS) control cards -EAI control the systems. The left card controls the left engine system and the right card controls the right engine system. The cards send electric signals to the EAI controllers to control the valves. EAI pressure sensors give control feedback.
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Fan Case Overheat
A fan case overheat detector monitors the EAI duct for leaks. The detector is part of the duct leak and overheat detection system (DLODS). The DLODS sends a signal to the EAI ACIPS control card. The card sends a signal to close the EAI valve. See the duct leak and overheat detection system section for more information (SECTION 26-18).
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本文链接地址：777 AMM 飞机维护手册 防冰和排雨 Ice and Rain Protection(5)
