777 AIRCRAFT MAINTENANCE MANUAL
RA SYSTEM -SELF TEST
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RA SYSTEM -GROUND TEST
General
There are only operational tests available for the radio altimeter system. These are the operational tests available:
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Center radio altimeter system
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Left radio altimeter system
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Right radio altimeter system.
Operational Test
The purpose of this test is to verify the operation and function of the radio altimeter transceivers.
This test does a check of the radio altimeter transceiver operation. The test also does a check of the transmission and receive antennas and their coaxial cables.
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777 AIRCRAFT MAINTENANCE MANUAL
RA SYSTEM -GROUND TEST
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777 AIRCRAFT MAINTENANCE MANUAL
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BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
WEATHER RADAR SYSTEM -INTRODUCTION
Purpose
The weather radar (WXR) system supplies:
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Visual indications of weather conditions
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Visual indications of land contours.
Description
The WXR system transmits radio frequency (RF) pulses in a 180 degree sector forward of the airplane path. Precipitation or terrain contours reflect the pulses back to the airplane.
Display
The WXR returns show in four different colors on the navigation displays (ND). The colors of the indications depend on the intensity of the returns.
Abbreviations and Acronyms
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AIMS -airplane information management system
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CMCF -central maintenance computing function
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CDU -control display unit
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CP -control panel
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GPWC -ground proximity warning computer
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MWL -master warning light
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ND -navigation display
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OPAS -overhead panel ARINC 629 system
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PFD -primary flight display
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PRF -pulse repetition frequency
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PWS -predictive windshear
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RA -radio altimeter
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RF -radio frequency
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RT -receiver-transmitter
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TCAS -traffic and collision avoidance system
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WES -warning electronics system
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WEU -warning electronics unit
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WX -weather
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WXR -weather radar
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WEATHER RADAR SYSTEM -INTRODUCTION
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WXR SYSTEM -GENERAL DESCRIPTION
Control
These components supply weather radar (WXR) system control:
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Left, center, and right control display units (CDUs)
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Left and right EFIS CPs
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WXR panel.
Display
WXR data shows on the navigation displays (NDs). The weather data from the WXR RT goes through the AIMS cabinets then to the NDs.
Antenna
The WXR antenna transmits the RF pulses and receives the RF returns. The RT gets air data inertial reference system (ADIRS) pitch and roll data from the airplane information management system (AIMS) cabinets for antenna stabilization.
Receiver-Transmitter (RT)
The central component of the WXR system is the weather radar receiver-transmitter (RT). The system has dual RTs. Only one RT operates at a time. The WXR RT does these functions:
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