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B. The wing anti-ice system consists of the distribution ducts, left and right control valves, the WING ANTI-ICE switch on the anti-ice rain removal module, and the wing anti-ice system relays. The system is powered by 115 volts ac from the 115 vac bus 2 and by 28 volts dc from the 28 vdc bus 2 through circuit breakers on the P6 panel.
Wing Anti-Icing Ducts
_____________________
A. The pneumatic bleed air supply is routed to the leading edge of each wing through control valves in the leading edge flap cavity near the outboard engines. The valve is joined to a Y-type coupling which connects to two elbows. The elbows direct air to the main anti-ice ducts which run inboard and outboard behind the leading edge.
B. Each duct is rigidly mounted to the leading edge structure at the elbow and is supported within the leading edge structure by heat resistant clamps. Cushions on the clamps allow the duct to expand as it heats up. Spray holes along the front of the duct direct the heated air throughout the leading edge surface. The air then flows along the leading edge skin and is exhausted overboard through drain slots in the bottom of the leading edge.
Wing Anti-Ice Control Valves
____________________________
A. The flow of air into the wing anti-ice ducts from the engine pneumatic system is controlled by a 3-1/2-inch shutoff valve in each wing. The butterfly type valve is driven open and closed by an internal electric motor. The valve has limit switches to prevent overtravel and valve position switches for fault indication. The valve has an external position indicator which shows the position of the valve, and a handle which allows the valve to be operated manually.
B. The wing anti-ice valve opens and closes in less than 3 seconds. The valve operates under a normal bleed air pressure of 45 psi at a temperature of approximately 350°F, and is designed to operate in external ambient temperatures of -65 to +300°F and with ducted air temperatures of -65 to 490°F. The valve will operate in altitudes to 45,100 feet.
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747-400
MAINTENANCE MANUAL
NACELLE 2 3 ANTI-ICE
ON
1 AUTO 4
OFF
SEE A
WING ANTI-ICE
AUTO
OFF ON
A
SEE B
FLIGHT COMPARTMENT
PNEUMATIC
MANIFOLD
WING THERMAL ANTI-ICE CONTROL VALVE
POSITION OF
SPRAY HOLES A
A
LEADING EDGE FLAP
B CUSHIONED CLAMP
WING THERMAL ANTI-ICE DUCT CLAMP ____ (EXAMPLE, ARROWS SHOW HEATED FLOW)
NOTE: LEFT WING TAI VALVE SHOWN,RIGHT VALVE OPPOSITE.
A-A Wing Thermal Anti-Ice System - Component Location Figure 1
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL
4. Wing Anti-Ice Control Switch and Relays
_______________________________________
A. The WING ANTI-ICE control switch is located in the anti-ice-rain removal module M7321 on the P5 pilots' overhead panel. The wing anti-ice system relays are located in the P415 panel in the main electrical equipment center.
B. The control switch has 3 positions to place the wing anti-ice system on, off, or in automatic mode under control of the ice detection system.
5. Operation (Fig. 2)
_________
A. Functional Description
(1)
The wing anti-ice system is enabled at lift off. Placing the WING ANTI-ICE switch in the ON position energizes the wing anti-ice valve relay, applying 115 volts ac to the opening contacts of each valve. The valve motor drives the valve open, and also drives the limit and valve position switches. Figure 2 shows each valve in the closed position, ready to power the opening winding of the valve motor.
(2)
When the valve is in transit, both contacts are closed. When the valve becomes fully open, the opening contacts break the circuit and the motor stops. When the control switch is placed in the off position, the wing anti-ice valve relay is de-energized, and the 115-volt ac supply is connected to the closing winding of the valve motor. The motor drives the valve closed, the closing contacts break the circuit, and the motor stops.
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本文链接地址：747-400 AMM 飞机维护手册 防冰和排雨 ICE AND RAIN PROTECTION(4)
