777 AIRCRAFT MAINTENANCE MANUAL
WES -ALERT AURAL GENERATION
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WES -AUDIO GAIN CONTROL
Audio Gain Levels
The WEUs set the audio output gain automatically. The audio gain range is from -6dbr to +6dbr from the reference value of 0dbr. The Odbr value is different for the various aural sounds the WEUs make.
Automatic Gain Control (AGC)
The WEUs control the audio output gain based on:
*
Flap and leading edge devices position
*
Landing gear position
*
Takeoff configuration warning enable. The WEUs make this enable signal when the conditions are good for a takeoff
*
Takeoff warning inhibit
*
Takeoff thrust
*
Computed airspeed (Vcas)
*
Landing mode. The WEUs make the landing mode signal when the flaps or leading edge devices are in landing position, the radio altitude is 800ft or less, and the computed airspeed is 80 knots or more
*
Fuel control switch position
*
Cabin pressure warning.
Manual Gain Control
Shop personnel use the manual gain control program pins to set the audio output gain manually.
An AGC enable/disable program pin sets manual or automatic gain control for the WEUs. If you leave the pin open, the WEU uses AGC control. If you ground the pin the WEU uses manual gain control.
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777 AIRCRAFT MAINTENANCE MANUAL
WES -AUDIO GAIN CONTROL
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WES -MASTER WARNING LIGHTS ACTIVATION
General
The left WEU connects to the left master warning light (MWL). The right WEU connects to the right master warning light.
Each WEU channel makes a MWL arm signal. A WEU channel must receive at least one MWL arm signal from another WEU channel before it makes the MWL activation signal.
The MWL activation signal makes the master warning lights come on.
Push the master warning lights to supply a reset signal to the WEUs. The reset signals make the master warning lights go out. If there is another warning condition, the master warning lights come on again.
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777 AIRCRAFT MAINTENANCE MANUAL
WES -MASTER WARNING LIGHTS ACTIVATION
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WES -FIRE WARNING
Fire Warning Inputs The fire warning logic sends the fire test signal to the alert aural
logic to make the fire bell and to the master warning light logic The fire warning logic gets fire warning inputs from the system
to make the master warning lights come on. cardfiles. These cards supply fire warning inputs to the WEUs:
*
Left engine fire detection card
*
Right engine fire detection card
*
APU fire detection card
*
Left and right ARINC signal gateway (ASG) cards.
Each WEU channel inhibits fire warnings when the airplane is in takeoff.
The alert aural logic makes the fire bell alert aural. The master warning light logic makes the master warning lights (MWLs) come on.
Push any master warning light to make the master warning lights and the fire bell go out.
Fire Test
When you do a fire warning test, the fire warning logic ignores fire warning inputs.
The fire warning logic makes a fire test signal. The fire warning logic makes the fire test signal only when at least one other WEU channel makes the same signal (2 of 4 vote).
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777 AIRCRAFT MAINTENANCE MANUAL 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：777 AMM 飞机维护手册 指示和记录系统 1(48)
