*
Airplane in the air less than 10 minutes.
With AUTO or ON selected, the operational mode is inhibited if any of these conditions occur:
*
Airplane on the ground (except during an initiated or periodic BITE test)
*
TAT is more than 50F (10C) and the time since takeoff is less than 5 minutes
*
Auto slat operation
*
Air-driven hydraulic pump operation
*
Engine start
*
Bleed air temperature less than 200F (93C).
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WING ANTI-ICE -FUNCTIONAL DESCRIPTION -ELECTRICAL
The WAI valves stay closed as long as the operational mode inhibit is active. If the valves are already open, the operational mode inhibit causes the valves to close.
ARINC 629 Interfaces
The OPAS sends WAI selector position and engine start selector position to the WAI ACIPS control card.
The EAI ACIPS control cards send ice detector data to the WAI system. With AUTO selected, the ice detection system controls operation of the wing anti-ice system.
The weight on wheels cards (WOW) send air/ground status to the WAI system. Wing anti-ice does not operate on the ground.
The air data inertial reference unit (ADIRU) sends mach number, static pressure, and total air temperature data to the WAI system. Mach number is an alternative to air/ground status if air/ground data is missing or not valid. The WAI BITE compares static pressure with WAI duct air pressure to make sure the WAI duct pressure sensors work correctly.
The warning electronic system (WES) sends auto slat operation data to the WAI system. The WAI valves close for a short time during auto slat operation. This makes more bleed air available to the air-driven hydraulic pumps.
EFFECTIVITY
BEJ ALL
The air supply and cabin pressure controller (ASCPC) sends a WAI shutoff signal to the WAI ACIPS control card if the air-driven hydraulic pumps are on or intermittent. Wing anti-ice does not operate during ADP operation.
The ASCPC sends pneumatic manifold temperature and pressure data to the WAI ACIPS control card. The control card uses this data to calculate the WAI air flow rate and valve position. The flow rate and valve position show on the ice protection maintenance page. Also, bleed air temperature less than 200F (93C) prevents wing anti-ice operation.
The ASCPC receives anti-ice air flow data from the WAI ACIPS control card. The ASCPC needs this data to calculate the bleed flow rate in the pneumatic system. The engine bleed air system flow limit function uses this flow rate. The flow rate shows on the air supply maintenance page. The ASCPC also needs anti-ice air flow data to set the air conditioning pack flow schedule.
The ECS miscellaneous cards (ECSMC) receive WAI valve position data from the WAI ACIPS control card. The ECSMCs need this data to control the aft and bulk cargo heating systems.
The AIMS primary display function gives EICAS messages, status messages, air synoptic information and maintenance page information related to the WAI system. The central maintenance computing function helps you isolate faults and lets you do ground tests.
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WING ANTI-ICE -FUNCTIONAL DESCRIPTION -ELECTRICAL
The flight management computing system (FMCS) gives takeoff mode information to the WAI ACIPS card. In takeoff mode, WAI does not operate for 10 minutes after the ground to air transition if the system is set to AUTO.
BITE
BIT circuits in the WAI ACIPS control card continuously monitor the wing anti-ice system. Faults that affect dispatch cause status messages. Other faults cause CMCS maintenance messages.
The BITE in the WAI ACIPS control card also does automatic power-up and periodic tests. Faults found during these tests that affect dispatch cause status messages. Other faults cause CMCS maintenance messages.
The power-up test occurs when the card gets power. BITE does a test of the card hardware and software functions and the valve and pressure sensor interfaces. The valves do not move during this test.
The periodic test occurs when all these conditions are true:
*
The airplane has been on the ground between 1 and 5 minutes
*
The WAI selector is set to AUTO or ON
*
Air-driven hydraulic pumps are not in intermittent operation
*
Bleed pressure is sufficient to open the WAI valves
*
The time since the last periodic test is more than 24 hours.
During this test, the WAI valves cycle open and closed. This test makes sure that valve malfunctions are detected.
Training Information Point
You do wing anti-ice system ground tests with the MAT. Two tests are available: one with bleed air and one without bleed air.
You use the MAT data load function to replace the WAI ACIPS control card software.
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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(4)
