CHAPTER
34
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34-CONTENTS
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777 AIRCRAFT MAINTENANCE MANUAL
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -INTRODUCTION
Pitot-Static System
The pitot-static system uses pitot probes and flush static ports to sense total and static air pressures. These pressures go to the air data inertial reference system (ADIRS) to calculate flight parameters such as air speed and altitude.
Air Data Standby Instruments
The air data standby instruments supply the flight crew alternate indications of the airplane altitude and indicated airspeed (IAS).
Abbreviations and Acronyms
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ADIRU -air data inertial reference unit
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ADM -air data module
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alt -altitude
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BITE -built-in test equipment
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CAS -calibrated air speed
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ELMS -electrical load management system
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LCD -liquid crystal display
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IAS -indicated air speed
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SAARU -secondary attitude air data reference unit
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SADM -standby air data module
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SAI -standby attitude indicator
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SALT -standby altimeter
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SASI -standby airspeed indicator
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typ -typical
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -INTRODUCTION
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -GENERAL DESCRIPTION
Pitot-Static System
The pitot-static system gets air pressure inputs from three pitot probes and six flush static ports on the airplane fuselage.
These are the two types of air pressure:
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Static air pressure. This is the ambient air pressure around the airplane
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Pitot air pressure. This is the air pressure on the pitot tube as a result of the forward motion of the airplane.
The pitot-static system has:
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3 pitot probes
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6 flush static ports
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Pneumatic lines.
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6 air data modules (ADMs)
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2 standby air data modules (SADMs).
The 777 has short flexible hoses that connect pitot probes to the pitot ADMs and pitot SADM. There is cross-fuselage hard tubing that connects pairs of static ports with the static ADMs and static SADM. The static ADMs and static SADM are in the center of the airplane and tubing runs. This reduces the amount of pressure lines and possible leaks from connections that occur in long tubing runs.
The pitot probes and static ports send the air pressures through lines to the ADMs and SADMs. The ADMs change the air pressures to electrical signals and send them to the air data inertial reference unit (ADIRU) and secondary attitude air data reference unit (SAARU) on the flight controls ARINC 629 data buses.
The ADIRU and SAARU use static air pressure and pitot air pressure to calculate airplane altitude and airspeed.
The standby airspeed indicator and standby altimeter get information directly from the SADMs on ARINC 429 data buses.
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -GENERAL DESCRIPTION
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -FLIGHT DECK COMPONENT LOCATION Air Data Standby Instruments
The standby airspeed indicator and standby altimeter are in the flight deck. They are flat panel liquid crystal displays (LCD).
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -FLIGHT DECK COMPONENT LOCATION
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -MEC COMPONENT LOCATION -1
General
The location of the left pitot air data module (ADM) is in the left forward section of the main equipment center.
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -MEC COMPONENT LOCATION -1
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PITOT-STATIC/AIR DATA STANDBY INSTRUMENTS -MEC COMPONENT LOCATIONS -2
Right and Center Pitot ADM Locations 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 導航 Navigation 1
