*
Duct pressure less than 11 psig and the related engine is on
*
Air synoptic display shows.
Secondary Engine Display
Duct pressure shows on the secondary engine display if one or both engines are off and the related engine fire switch is not pulled.
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PNEUMATIC -INDICATIONS -EICAS DISPLAY AND SECONDARY ENGINE DISPLAY
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777 AIRCRAFT MAINTENANCE MANUAL
THIS PAGE IS INTENTIONALLY LEFT BLANK
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PNEUMATIC -INDICATIONS -AIR SYNOPTIC DISPLAY
Air Synoptic Display
The lower part of the air synoptic display gives information about the pneumatic system, air conditioning zone temperature control system, cargo heat systems, and air user system.
See the air conditioning chapter for more information about the temperature control and cargo heat systems (CHAPTER 21).
For the pneumatic system the display shows:
*
Air flow direction and user systems
*
Isolation valve position
*
Duct pressure (manifold duct pressure)
*
Engine bleed valve (PRSOV) calculated position
*
APU shutoff valve position
*
Air source status (engine, APU and ground).
Green flow bars show air flow direction and identify which sources and users are on.
Valve positions show as one of the following symbols:
*
Open (white circle with flow bar in-line with duct)
*
Closed (white circle with flow bar 90 degrees to duct)
*
Failed open (amber valve open symbol with amber X)
*
Failed closed (amber valve closed symbol with amber X)
*
Selected closed (amber valve closed symbol with amber X) for isolation and APU shutoff valves only
*
Invalid (white circle with no flow bar).
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The units of duct pressure are psig. The color of the pressure readout changes from white to amber when pressure is less than 11 psig. No pressure will show if any of these conditions occurs:
*
Related ASCPC primary (digital) control fails
*
Fault in the indication circuit.
Air source status for the engines is not shown on the air synoptic display. Air source status for the APU shows by color change of the APU symbol. The APU symbol is white for APU off and green for APU on. The ground air symbol shows if manifold duct pressure is more than 11 psig and all of the following are true:
*
Airplane on the ground
*
No active engine or APU bleed air sources or any active bleed sources isolated from ground air source
*
User system on (pack, trim air, WAI, starter, ADP).
Training Information Point
The related ASCPC calculates engine bleed valve (PRSOV) position. Actual valve position does not always agree with the position shown on the air synoptic display. If you must make sure that the PRSOV is open or closed, do a check the position indicator on the valve.
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PNEUMATIC -INDICATIONS -AIR SYNOPTIC DISPLAY
The positions of the isolation valves and the APUSOV, are usually based on actual valve position measured by RVDTs. If a RVDT fails, the related valve position is calculated by the related ASCPC. If the related ASCPC has a failed primary control, then valve position information will show as invalid.
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PNEUMATIC -INDICATIONS -AIR SYNOPTIC DISPLAY
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PNEUMATIC -INDICATIONS -AIR SUPPLY MAINTENANCE PAGE
Air Supply Maintenance Page
The upper part of the air supply maintenance page contains information about the pneumatic system. The primary control (digital) part of left and right ASCPCs and the EEC supply the information. The ASCPCs supply most of the information. This information comes from the EECs:
*
STARTER VLV position
*
ENG HIGH STAGE PRESS
*
ENG N1 FAN SPEED.
Valve positions are shown as OPEN or CLOSED. Pressure values are shown in psig. Temperature values are shown in degrees C. Flow rate values are shown in cubic meters/min.
Flight phase may be any one of these:
*
Initialization (INIT)
*
GND
*
TAKEOFF
*
CLIMB
*
CRUISE
* 中國航空網 m.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：777 AMM 飛機維護手冊 氣源 Pneumatic(5)
