NAVIGATION
CH 34
ATA 34 NAVIGATION SYSTEM TABLE OF CONTENTS
NAVIGATION SYSTEM TOC: ... 2
NAVIGATION INTRODUCTION ... 5
PITOT STATIC COMPONENT LOCATIONS ... 9
AIR DATA INERTIAL REFERENCE SYSTEMS... 17
ADIRU COMPONENT LOCATION... 21
ADIRU INITIALIZATION ... 23
ADIRU (ADC) TEST ... 43
ADIRU (IR) TEST ... 49
ADIRS DISPLAY AND SWITCHING ... 51
ALTERNATE VMO/MMO SELECT SWITCH ... 59
REDUCED VERTICAL SEPARATION MINIMUMS... 63
ANTENNA LOCATIONS... 65
RADIO ALTIMETER INTRODUCTION... 67
RADIO ALTIMETER SELF TEST ... 72
ALTITUDE ALERT SYSTEM ... 75
INSTRUMENT SYSTEM FLIGHT DISPLAY ... 81
EFIS - INTRODUCTION ... 85
EFIS EADI AND EHSI DISPLAYS... 97
VSI OVERVIEW... 101
VOR - INTRODUCTION ... 105
VOR SELF-TEST (MEC COMPARTMENT) ... 115
DME - INTRODUCTION ... 117 DISTANCE DISPLAY ... 123 GPS - INTRODUCTION ... 129 GENERAL DESCRIPTION ... 133 GPS COMPONENTS ... 137 OPERATION MODES... 141
RADIO DISTANCE MAGNETIC INDICATOR (RDMI) ... 147
ILS - INTRODUCTION... 151
ILS - DISPLAYS... 163
SELF-TEST SEQUENCE ... 165
MARKER BEACON - INTRODUCTION... 167
ATC - INTRODUCTION ... 173
TCAS - INTRODUCTION... 181
TCAS OPERATIONAL TEST... 187
WEATHER RADAR - INTRODUCTION... 193
WEATHER RADAR DISPLAYS... 199
PREDICTIVE WINDSHEAR THEORY ... 201
WEATHER RADAR TEST DISPLAYS... 205
EGPWS - INTRODUCTION... 209
EGPWS - COMPONENT LOCATIONS ... 217
WINDSHEAR MODE ... 227
FMCS - COMMUNICATION, NAVIGATION, SURVEILLANCE... 231
FLIGHT MANAGEMENT LOCATIONS... 241
MULTIFUNCTION CONTROL DISPLAY UNIT (MCDU) ... 245
FLIGHT MANAGEMENT COMPUTER INPUTS... 249
MAINTENANCE INDEX PAGE... 261
NAV DATA CROSSLOAD PAGE ... 263
NAVIGATION INTRODUCTION
General
Pitot/Static System - senses dynamic (pitot) and ambient (static) air pressure and supplies these to the standby altitude and airspeed indicators and to the air data computers which compute and display air data parameters.
Air Data Computing System - computes airspeed, altitude, mach number and temperature data and supplies it in digital format to interfacing systems. Air Data Instrument Systems - displays airplane speed and altitude on both pneumatic and electronic displays.
Altitude Alert System - provides aural and visual alert indications when the airplane approaches or departs from a selected altitude.
Inertial Reference System (IRS) - primary reference source for attitude and navigation displays and autoflight systems. The IRS determines and provides angular rates and accelerations and computes attitude, true and magnetic headings, velocity and present position.
Electronic Flight Instrument System (EFIS) - the primary navigation display system utilizes the electronic attitude display indicator (EADI), the electronic horizontal situation indicator (EHSI), radio distance magnetic indicator (RDMI), and the vertical speed indicator (VSI). The EADI and EHSI are CRT displays driven by one of 3 symbol generators. The EADI provides primary attitude, flight director and autoflight mode annunciation. The EHSI is the primary navigation display.
Standby Magnetic Compass - an independent compass providing a backup indication of the airplane's magnetic heading.
Standby Attitude Reference System - provides a backup indication of pitch, roll, and ILS displays.
ILS Navigation System - determines lateral (localizer) and vertical (glideslope) deviations which are displayed by the EADI and EHSI.
Marker Beacon System - provides visual and aural indications when the airplane flies over various types of marker beacons.
Radio Altimeter System - determines airplane height above the terrain for display and use by other systems.
Weather Radar System - displays areas of precipitation ahead of the airplane on the EHSI and a weather radar indicator.
Ground Proximity Warning System (GPWS) - provides aural and visual warnings on the airplane's approach toward terrain, windshear, or departure below glideslope path, by monitoring ILS, IRS, radio altitude, and ADC data. VOR System - determines bearing with respect to ground-based VOR stations. Air Traffic Control (ATC) System - derives air data for transmission with selected code and identification to the ground in response to ATC interrogation.
Distance Measuring System (DME) - determines slant range distance from the airplane to DME ground stations and displays it on the RDMI and EHSI.
Flight Management System (FMS) - provides navigation and performance data to the autoflight systems and the flight instrument systems. The FMS
AIR DATA INSTRUMENTS - INTRODUCTION
General
The pitot-static system senses the dynamic (pitot) and ambient (static) air pressure external to the airplane. It supplies these two pressures to various systems for determining airplane altitude and motion through the air mass.
The system consists of aerodynamic compensated pitot-static probes, static ports, drain fittings, and pneumatic tubes and hoses.
The pitot and/or static pressures are supplied to the standby altimeter and standby airspeed indicator. They are also supplied to the
differential pressure transducer, passenger signs pressure sensor, RAT ARM Q switch, air data and elevator feel computers.
AIRPLANES WITH INTEGRATED STANDBY FLIGHT DISPLAY; The pitot and/or static pressures are supplied to the Integrated Standby Flight Display. They are also supplied to the differential pressure transducer, RAT ARM Q switch, air data and elevator feel computer. Electrical power is required only for the pitot-static probe anti-icing heaters.
PITOT STATIC COMPONENT LOCATIONS
Pitot-Static Probe
Two pitot-static probes are installed on the left lower nose section at station 200, and two pitot-static probes are installed on the opposite location.
Each pitot-static probe provides one dynamic and two ambient pressure inputs to various pitot-static subsystems. Pitot pressure is sensed through a single pitot opening at the tip of the probe. Static pressure is sensed through two sets of independent static ports located on the probe. Each pressure source is connected to its respective system.
Each probe is installed with mounting screws with the probe base having two index pins to ensure proper probe alignment. A gasket is installed between the probe base and the airplane structure to form a pressure seal. The probes are not interchangeable with the probes on the opposite side of the airplane. Heaters are provided for pitot-static probe anti-icing.
PITOT-STATIC DRAIN LOCATIONS
Pitot-Static System Drains
The pitot-static system drains are concentrated in four areas:
• Forward equipment center (left and right sides of the nose wheel well) • Main equipment center (on stanchions of the electronic racks, left and right
sides)
• Aft cargo compartment (on left side, near the door)
• Stabilizer compartment (on the left side, behind pressure bulkhead) The system drain acts as a sump to remove condensation collected from the pitot-static lines. The sump has a reinforced transparent section of tubing with an orange float. This forms a sight gage to indicate the level of liquid
accumulated in the sump.
The lower portion of the drain contains a poppet valve covered by a bayonet cap. To drain the pitot static line, the cap is removed and the valve depressor on the cap is inserted into the poppet valve. Accumulated liquid in the sump is drained by gravity flow as the valve is depressed.
Note: The transparenet tubing is not skydrol resistant. If the elevator feel computer leaks skydrol into the static line, the lines must be flushed, and a drain may need to be replaced.
STATIC COMPONENT LOCATIONS
Alternate Static Port
The alternate static ports are flush mounted on each side of the lower forward fuselage at body station 465. Anti-icing heaters are not provided on the ports.
Each of the two ports is an independent sensor of external ambient pressure. The static port is cross connected with the port on the opposite side. It provides an alternate source of ambient pressure for the air data instruments. At the port, pressure is sensed through small holes open to the static line tubing.
PITOT STATIC SYSTEM SCHEMATIC
Inputs
The pitot probes sense total pressure. Openings along the pitot probe and the flush-mounted static ports sense ambient (static) pressure. Static sources are cross-connected to compensate for airplane maneuvers.
Distribution
Tubing connects the pressure sensors to pressure-sensitive devices in indicators and computers. The standby altimeter, standby airspeed indicator, and cabin differential pressure indicator convert the air pressures into visual indications. The differential pressure sensor (used to compute cabin differential pressure) is a piezoelectric pressure transducer located below the flight compartment. Pressures are also used in the air data computers and the elevator feel computer. Control circuits for the ram air turbine (RAT) utilizes pitot/ static inputs from the RAT airspeed switch to prevent premature deployment.
Drains are located at low points in the tubing to allow moisture condensation to be removed from the system. The tubing is mounted so that moisture flows down to these drains for all normal airplane attitudes.
Air Data Modules
Air data modules (ADM) connect to pitot and static component to supply digital information to the ADIRU’s.
AIR DATA INERTIAL REFERENCE SYSTEM
General
The air data inertial reference system provides air data outputs to the air data instruments and inertial reference data to other interfacing systems. The system consists of two total air temperature (TAT) probe, two air data inertial reference computers (ADCs), and two angle of attack (AOA) sensors, inertial mode reference panel (IRMP) and air data modules (ADM). The system also has three external test switches
ADIRU GENERAL DESCRIPTION
General
The air data inertial reference system provides air data outputs to the air data instruments and inertial reference data to other interfacing systems. The system consists of two total air temperature (TAT) probe, two air data inertial reference computers (ADCs), and two angle of attack (AOA) sensors, inertial mode reference panel (IRMP) and air data modules (ADM). The system also has three external test switches.
AIR DATA INERTIAL REFERENCE SYSTEM COMPONENTS
Component Locations
• Air Data Inertial reference units - Located on E1-6 • Inertial reference mode panel - Located on P5
• Vertical speed indicators - Located on captain's or first officer's instrument panels, P1 and P3
• IRS DC power disconnect relay - Located on P6
• AC circuit breakers - One 115 volt ac circuit breaker for each IRU is located on P11
• DC circuit breakers - One 28 volt dc circuit breaker for each IRU is located on P6
ADIRU Purpose
The air data inertial reference unit (ADIRU) contains three laser gyros for sensing airplane angular rate about the pitch, roll, and yaw axes, and three accelerometers for sensing linear acceleration along the airplane longitudinal, lateral, and vertical axis. An internal digital computer uses these signals to calculate airplane present position.
Motion Detection
If motion is detected during the align mode, the alignment will automatically be restarted 30 seconds after the motion has stopped. This restarted alignment will require only 8 minutes, omitting the usual 2 minute initial standby time. Also, the initial present position will be either the most recent pilot entry made during the align mode (either before or after the restart) or the last computed position before a down mode alignment if no pilot entry was made.
Auto-calibrate Function
Any change in pitch, roll or yaw caused by biasing errors results in appropriate corrections, rather than continuing to use initial conditions.
Drift Angle Tolerance
External drift angle limited to 60 degrees before the IRU output is tagged invalid. Latitude Comparisons
During initialization, entered latitude is compared to the last stored latitude immediately following entry, and again with the computed latitude after ten minutes in align mode. In the event of no initial position entry during the 10 minute align period or a miscompare (requiring another entry) is detected, the IRU will flash the ALIGN Light.
Time to Nav
The IRU has the capability to display on the IRMP the time remaining, in minutes, until completion of alignment.
Barometric Altitude Tolerance
The ADIRU barometric altitude reasonableness limit test tolerates a barometric altitude input of (-) 2000 feet to prevent false VSI flags during extremely high barometric pressure periods.
Post-Shop-Visit Position Compare
No initialization position comparison to the last stored position is made during the first alignment cycle following a shop visit by the ADIRU.
Attitude Mode Select Delay
The ADIRU delays actual entry into attitude mode for 2 seconds after selection in order to preclude accidental selection of the attitude mode by overshooting the NAV position of the mode select switch.
ADM COMPONENT LOCATIONS
General
There are 7 Air Data Modules located in the Forward end of the main equipment center, just aft of the forward equipment compartment. There are 4 ADM’s on the left and 3 ADM’s on the right side.
ADIRU - INTRODUCTION
Purpose
The Air Data Inertial Reference System is one of the primary sensing systems. It provides the primary and navigational parameters indicated in the associated graphic.
System Components
The system consists of three Air Data Inertial Reference Units (ADIRU’s) which sense: angular rates about the X (roll) axis, Y (pitch) axis, and Z (azimuth) axis using laser gyros; and, linear accelerations along the same three orthogonal axes using accelerometers. The inertial reference mode panel (IRMP) provides system control. The ADIRS system conforms to ARINC 704, as well as ARINC 600 and ARINC 429.
Inputs
Air data provides barometric altitude and altitude rate for altitude and vertical speed damping. It also provides true air speed for wind computations. The control display units of the flight management computer system can be used for system initialization.
System Controls
The inertial reference mode panel (IRMP) provides system mode selection, system monitoring and an alternate method of initialization.
System Outputs
A number of airplane systems use the ARINC 429 outputs of the system, including display indicators of the flight instrument system.
AIR DATA DIGITAL INPUT/OUTPUT INTERFACES
Inputs
Air data provides barometric altitude and altitude rate for altitude and vertical speed damping. It also provides true air speed for wind computations. The control display units of the flight management computer system can be used for system initialization.
Pitot and Static inputs are sent to Air Data Modules (ADM) and converted to digital signals for the ADIRU.
Outputs
ADIRU outputs are sent for display to the GGU’s the to the Large Display System (LDS). Outputs are also sent to other various systems for processing.
ADIRS THEORY OF OPERATION
Navigation Alignment
During alignment the air data inertial reference system determines the local vertical, the direction of true north, and the initial latitude.
Gyrocompass Process
Inside the inertial reference unit, the three gyros sense angular rate of the airplane. Since the plane is stationary during alignment, the angular rate is due to earth rotation. The ADIRU computer uses the direction of angular rate to determine the direction of true north.
Initial Latitude and Longitude
During the ten minute alignment period, the ADIRU computer has determined true north by sensing the direction of the earth rotation. The magnitude of the earth rotation vector allows the ADIRU computer to estimate latitude of the initial present position. This calculated latitude is compared with the latitude entered by the operator during initialization. Longitude cannot be determined by the ADIRU during alignment
However, the longitude entered by the operator during initialization is compared with the longitude stored in memory the last time the ADIRU was powered down.
Present Position
During initialization, the latitude and longitude of the starting point are entered into the air data inertial reference unit computer. Present position at all future times is determined by adding the distance traveled onto the coordinates of the initial starting position.
Distance traveled is determined by measuring linear acceleration (from the accelerometers) and integrating the result to obtain velocity and integrating again to obtain distance.
Triple Axis Navigation Computation
As long as the airplane flies in only one direction, one accelerometer is sufficient to determine distance traveled from the starting position. Since the airplane may fly in any direction, three accelerometers, mounted to sense acceleration 90 degrees apart, are required.
The three accelerometers are stationary relative to the airplane frame. To determine how much acceleration is causing horizontal movement on the earth, the outputs to the accelerometers have to be compensated by the ADIRU computer, taking into account the airplane attitude and earth curvature. The compensated outputs from the accelerometers are vector added to
determine the actual direction of travel and the amount of travel horizontally. In general, the accelerometers are not oriented north-south and east-west but, their output signals can be related to a north-east coordinate system and the present position can then be determined in terms of latitude and longitude.
INERTIAL REFERENCE MODE PANEL
Mode Select Switches
Each inertial reference unit is controlled by its mode select switch on the IRMP. Each mode select switch has four positions:
OFF - removes power from the ADIRU except for logic circuitry associated with the power-off functions.
ALIGN - the inertial reference unit uses earth rotation and gravity to align its reference to the local vertical, to locate true north, and to estimate latitude. Airplane present position must be entered before alignment is completed. While ALIGN or NAV is selected, the time-to-NAV (TTN) will be displayed in the upper right display window as long as the DSPL SEL switch is in the HDG position. As soon as NAV mode is attained, this display will blank.
NAV - the inertial reference system performs unaided inertial navigation. NAV position has a detent which requires a pull force when switching from NAV to OFF, ALIGN, or ATT. This prevents inadvertent switching from the NAV mode. ATT - provides rapid attitude and heading restart after total power shutdown to the ADIRU. ATT may also be selected if a fault prevents navigation
computations but the ATT mode is still operational. Mode and Status Annunciators
There are twelve annunciators on the IRMP, four for each ADIRU: • ALIGN - illuminates white when the ADIRU is in the alignment mode
(approximately 10 minutes if the mode select switch is in NAV). It remains illuminated as long as the mode select switch is in ALIGN. The ALIGN annunciator flashes if the alignment procedure fails.
• ON DC - illuminates amber to indicate that the IRU is operating on battery power because 115 volts ac is not available. When the system is initially turned on, the ON DC annunciator illuminates momentarily because the IRU switches off 115 volts ac to verify that battery power is available. This is a normal result of the power-up sequence test done by the ADIRU.
• DC FAIL - illuminates amber when the battery power source drops below 18 volts dc. ON DC and DC FAIL cannot both be on at the same time. • FAULT - illuminates amber when IRS failures are detected.
DSPL Select Switch
• TK/GS (Track angle/ground speed) - True track angle from 0 through 359.9 degrees is displayed in digits 3 through 6, with a resolution of 0.1 degree. Ground speed from 0 through 2,000 knots is displayed in digits 10 through 13, with a resolution of 1 knot.
Example: 123.4 degrees 321
• PPOS (Present position) - Latitude from 90 degrees S to 90 degrees N is displayed in digits 1 through 6, and longitude from 180 degrees E to 180 degrees W is displayed in digits 7 through 13. Resolution is 0.1 minute. Example: N89 degrees 59.9' W179 degrees 59.9'
• WIND (Wind angle/wind speed) - True Wind angle from 0 to 359 degrees is displayed in digits 4 through 6 with a resolution of 1 degree. Wind speed from 0 through 256 knots is displayed in digits 11 through 13 with a resolution of 1 knot.
Example: 321 degrees 50
• HDG (Heading) - True heading from 0 to 359.9 degrees is displayed in digits 3 through 6 with a resolution of 0.1 degree. Digits 7 through 13 are blank.
Example: 123.4 degrees Keyboard
The twelve-key keyboard allows entry of initial latitude and longitude when in ALIGN and of set-magnetic-heading when in ATT. The keyboard has 12 panel lamps for keyboard lighting, which use the variable zero-to-five volt ac signal provided by the aircraft light dimming control circuits.
ADIRU INITIALIZATION USING FMC CDU
General
The inertial reference system can be initialized by entering present position on the control display unit of the flight management computers (FMC CDU) or by using the IRMP. Initializing with the FMC CDU or the IRMP requires the data be entered only once for those ADIRU’s currently in the alignment procedure, as indicated by the ALIGN annunciators.
Initialization Procedure (FMC CDU)
Place the ADIRU’s in ALIGN or NAV modes using the mode select switches on the IRMP. Observe that the ON DC annunciator and then the ALIGN
annunciator illuminate for all three ADIRU’s.
• Call up the position initialization page on the FMC CDU by pressing the
INIT/REF key on the CDU
• SET IRS POS. (5R) will contain box prompts which will allow present position data entry. Use one of the following ways to enter present • position. If 5R blank, data cannot be entered.
• Scratch pad entry. Enter a latitude and longitude into the scratch pad by pressing the alphanumeric keys. Line select (press) 5R and the scratch pad contents will transfer to the SET IRS POS
• Enter LAST POS. Line select (press) 1R. LAST POS. latitude and longitude appear in the scratch pad. Line select (press) 5R and the scratch pad contents are transferred to the SET IRS POS
• Enter REF AIRPORT. Use alphanumeric keyboard to select the four character ICAO airport identifier. Line select the scratch pad contents into the REF AIRPORT line (2L). Stored latitude and longitude for the airport will be displayed on line 2R. Line select (press) 2R and the latitude/ longitude will transfer to the scratch pad. Line select (press) 5R and the scratch pad contents are transferred to the SET IRS POS
• Enter GATE. Line select into 2L a REF AIRPORT as shown previously. Gate identifiers associated with the REF AIRPORT are the only valid entries. Use alphanumeric keyboard to select the GATE (format is 5 characters maximum). Line select (press) 3L to transfer the scratch pad contents to GATE. Stored latitude and longitude will be displayed on 3R. Line select (press) 3R and the latitude/longitude will transfer to the scratch pad. Line select (press) 5R and the scratch pad contents are transferred to the SET IRS POS
Verify the ADIRU’s have accepted the initialization latitude/ longitude by checking the display window on the IRMP with PPOS selected on the DSPL SEL switch. The POS. REF page also will display acceptance of latitude/ longitude by the ADIRU’s. To access POS REF, press the NEXT PAGE key on the CDU while the POS. INIT page is displayed. If an ADIRU does not reflect back the entered coordinates within 5 seconds after they were entered, the FMC CDU will display an alert message in the scratch pad, RE-ENTER IRS POSITION.
ADIRU NORMAL ALIGNMENT PROCEDURE
General
During the alignment process, the ADIRU determines the local vertical and the direction of true north. The airplane cannot be moved during alignment. Normal Procedure
Alignment can be achieved by the procedure shown with the mode select switches in ALIGN. Normally alignment takes a minimum of ten minutes at which time the ADIRU’s are ready to be switched into the NAV mode. The operator must insert present position sometime during the alignment process using either the FMC CDU or the IRMP. Problems with the alignment process are indicated by a flashing ALIGN annunciator or steady FAULT annunciator on the IRMP.
The alternate alignment procedure is to move the IRMP mode select switch directly into NAV. The ADIRU automatically advances to the navigate mode at completion of the ten minute alignment if present position has been entered. If a problem occurs during alignment, the fault annunciator illuminates, and if present position has not been entered by the time alignment is complete the ALIGN annunciator flashes.
Time-To-Navigation Mode Display
The time interval, in minutes, for an ADIRU to enter the navigation mode may be displayed as depicted on the graphic.
ADIRU INITIALIZATION - USING IRMP
The IRMP can also initialize the inertial reference system. Present position is entered into all ADIRU’s that are aligning, as indicated by ALIGN annunciators. Initialization must occur before the ADIRU’s will complete the alignment process.
Procedure
The Procedures to align are as follows:
Place mode select switches for the ADIRU’s in ALIGN or NAV. Check that the ON DC annunciators illuminate momentarily and then the ALIGN annunciators. Place DSPL SEL in PPOS position (to verify IRU has been initialized).
Enter the latitude and longitude of present position with the keyboard. Either latitude or longitude can be entered first.
For latitude, press N2 or S8 key. The letter N or S will appear on the left digit of the left display and the rest of the display will blank.
Continue to enter latitude. As a key is pressed, the digit appears in the right digit of the left display and remaining digits shift one to the left. Press ENT to enter the latitude into the ADIRU computer.
Longitude is entered in the right display in a similar way, starting with the W4 or E6 key. Press ENT to enter the display information into the IRU computer. The IRU selected by the SYS DSPL switch should return the entered latitude and longitude to the display.
If a mistake is made before ENT is pressed, the CLR key allows the displays to be cleared.
ADIRU NORMAL ALIGNMENT PROCEDURE
ON N101FE IRMP STARTS AT 6 AND GOES DOWN
TOTAL TIME TO ALIGN TIMED AT 4 MIN 39 SEC
IR ADVISORY STATUS AND MAINTENANCE MESSAGES
General
To see ADIRU stored maintenance messages on the IRMP panel: • Select desired ADIRU
• Display Switch to “HDG” • Type 01
• Then push “CLR” to advance to the next code.
INERTIAL REFERENCE SYSTEM FMC MESSAGES
General
FMC messages are provided to assist the operator during IRS alignment. These messages (Table 1) are generated using FMC logic and ADIRU digital discretes (ARINC 429 dataword label 270). Whenever an IRS/FMC message is shown, the EICAS level B message FMC MESSAGE is shown and the amber FMC annunciator (PI-3) is illuminated.
ADIRU ATTITUDE MODE
General
In the attitude mode, the ADIRU has only limited capability and few outputs, the most important of which is pitch and roll attitude. This mode is entered by moving the mode select switch to the ATT position.
The attitude mode has only limited use. It could be selected in either of two situations. One situation would be if only attitude information is needed. This could occur if a weather radar check is required on the ground.
Another situation would be if the ADIRU navigation functions fail but the attitude functions remain operational. An example of the second situation would happen if an ADIRU had an AC and DC power interruption in flight.
When the attitude mode is selected, the ADIRU is latched into this mode even if the switch is moved to ALIGN or NAV. To select another mode, OFF must be selected first.
Attitude Outputs
When the ATT position of the mode select switch is selected from OFF or ALIGN or NAV, a thirty second alignment period is required. During this time local vertical is sensed. After the alignment period, pitch and roll attitude, accelerations, and inertial vertical speed are output.
Heading Outputs
If ATT is selected and a magnetic heading output is desired, the heading has to be initialized through the FMC CDU or the IRMP. If magnetic heading is initialized, the ADIRU will use this as initial magnetic heading output and will change magnetic heading output as the platform heading changes.
AIR DATA TEST AND DISPLAYS
ADIRU and Yaw Damper Test Switches
Both the ADIRU and yaw damper test (from the test panel on P61) causes all three ADIRU’s to go into self-test. The test mode is inhibited in the NAV mode when ground speed is greater than 20 knots, and it is also inhibited in the ATT mode.
If possible, turn off the hydraulics to the yaw damper before pushing the ADIRU or the yaw damper test switch.
Performing the ADIRU or yaw damper test with the hydraulic system pressurized causes movement of the rudder assembly.
WARNING:
ALL CONTROL SURFACES ARE HYDRAULICALLY POWERED AND MAY MOVE WHEN ANY HYDRAULIC SYSTEMS ARE PRESSURIZED, OR IF ANY CONTROLS ARE MOVED. ALL PERSONNEL AND STANDS SHALL BE CLEAR OF CONTROL SURFACES AND CONTROL COLUMN WHEN HYDRAULIC SYSTEMS ARE PRESSURIZED.ADIRU Test Switch
The test mode is inhibited in the NAV mode when ground speed is greater than 20 knots, and it is also inhibited in the ATT mode.
Test Results - IRMP
Initiating a self-test causes all annunciators for that ADIRU to illuminate for two seconds. Also, all segments of the display are illuminated for two seconds (except the most significant character of longitude reads 1). After ten seconds, the ADIRU outputs go to preset test values briefly.
The master dim and test switch may be used to test the IRMP instead of the test switch on each individual ADIRU. If the master dim and test switch is to be
used, all three ADIRU’s should be installed or the master dim and test IND LTS switch should be in the BRT position.
CAUTION: DO NOT OPERATE MASTER DIM AND TEST SWITCH FOR MORE THAN FIVE MINUTES WITH MASTER DIM AND TEST IND LTS SWITCH IN DIM POSITION WHEN ANY OF THE THREE ADIRU’S ARE REMOVED. DAMAGE TO THE IRMP CAN RESULT.
ADIRU (ADC) TEST (TYPICAL)
Test Initiation
There is no test that can be initiated on the ADIRU. On the P61 test panel:
The identical test for the left or right air data computer is initiated by moving the spring loaded, center-off, toggle switch up to the "L ADC" or "R ADC" position. Note: Test capability via the test panel on P61 is inhibited in flight. Test Results
ADIRU TEST DISPLAYS
EICAS
Several air data parameters are available on the EICAS displays. TAT is always displayed as a primary display. TAT, CAS, MACH and ALT can be displayed on the lower EICAS display unit by pressing the PERF/APU key on the EICAS maintenance control panel (P61).
Because these parameters are found on the EICAS maintenance pages, they are only available on the ground. These parameters are an excellent method for cross-checking TAT, CAS, MACH, and ALT test values during air-data self tests.
FMC
TAS and SAT are shown on the flight management computer control display unit (FMC-CDU) on PROGRESS page 2/2. Pressing the PROG key will display page 1/2. Pressing the NEXT PAGE key will display page 2/2 on which TAS and SAT are located.
IR SELF TEST AND DISPLAYS
ADIRU Test Switches
Moving the ADIRU test switches down (from the test panel on P61) causes all three ADIRU’s to go into self-test of the inertial reference system. The test mode is inhibited in the NAV mode when ground speed is greater than 20 knots, and it is also inhibited in the ATT mode.
The test will perform the following:
ADI tilt to 45 degrees roll and 5 degrees pitch up HSI Magnetic heading will go to 15 degrees
IRMP will go to all indicators on for 2 seconds then off for 2 seconds
Depending on what position is selected on the IRMP (TK/GS, PPOS, WIND, or HDG) indications are shown for each display position.
TK/GS - 00 200
PPOS - N 22300 E 22300 WIND - 30 100
ADIRS DATA DISPLAY AND SWITCHING
Instrument Source Select Panel
ADIRS source select switches allow the captain (P1-1) and first officer (P3-3) to switch between the normal (on side ADIRU) and alternate (center IRU) source of ADIRU data.
Switch push-button illuminates white when switch is in ALTN position. Radio Distance Magnetic Indicator
The RDMI's display magnetic heading information supplied by the offside selected IRU.
The HDG failure flag appears on the instrument face if the ADIRU magnetic heading is invalid or NCD.
Vertical Speed Indicator
The VSI displays vertical speed from the on side selected ADIRU. The OFF failure flag appears if ADIRS VSI data is invalid or NCD. Electronic Horizontal Situation Indicator
The EHSI displays heading information supplied by the selected on side ADIRU. Track and wind data is dynamic data from the selected FMC, but defaults automatically to the ADIRU.
ADIRS failures cause removal of ADIRS-related Symbology and display of the TRK failure flags.
Electronic Attitude Director Indicator
The EADI displays pitch and roll from the selected ADIRU. Ground speed is dynamic data from the selected FMC that defaults automatically to the IRU. ADIRS failures cause removal of ADIRS-related Symbology and display of the ATT failure flag.
ADIRU ALIGNMENT INDICATIONS
General
This table lists the indications visible on the IRMP during the IRS alignment process. In general, the FAULT annunciator is on steady for faults, and the ALIGN annunciator flashes if operator attention is needed.
Longitude Comparison
The ADIRU compares the longitude entered during initialization with the longitude stored in memory of the last position. If the two differ by more than one degree, the ALIGN annunciator flashes immediately. If the ADIRU was newly installed or the airplane ferried without using that ADIRU, this would be a normal display. Entering the longitude a second time forces the IRU to accept the new longitude.
Latitude Comparison
The ADIRU compares the latitude entered during initialization with the last position latitude stored in memory. If the two differ by more than one degree, the ALIGN annunciator flashes immediately.
The latitude entered during alignment is stored until alignment is completed. After the alignment is completed the ADIRU compares latitude calculated with the latitude entered for initialization. If the two do not agree, the ALIGN annunciator flashes. If the same latitude entered the second time still does not compare with calculated latitude, the FAULT annunciator illuminates and the ALIGN light comes on steady.
If the two entries mentioned above were done with wrong latitude values, a subsequent entry of the correct latitude will be accepted by the ADIRU and the fault light and the ALIGN light will extinguish.
ADIRS INPUTS
System Power
Normal system power is 115 volts ac from circuit breakers on the P11 panel with 28 volts dc from the hot battery bus providing a backup power source. For system startup, ac or dc power must be available.
Switching to 28 volts dc is accomplished automatically by the ADIRU’s when loss of 115 volts ac is sensed. Five minutes after 28 volts dc is supplied from the main battery relay, the backup hot battery bus 28 volts dc is removed from the right IRU by the IRS DC power disconnect relay. The center and left ADIRU’s remain powered from the airplane battery. During autoland the center bus isolation relay K123 inhibits the IRS DC power disconnect relay.
Note: After a five minute time delay due to AC power lost the left and center ADIRU’s will shut down with the right continuing on DC power until the aircraft battery is depleted.
ADIRS Inputs
The inertial reference mode panel provides mode select discretes to the ADIRU’s.
The left and right air data computers provide altitude, altitude rate, and true airspeed. For the left and right ADIRU’s, the ADC is selected by the on side ADC instrument source select switch. The center ADIRU receives a switching discrete from the first officer's IRS source select switch to control which (left or right) ADC input it uses. In the normal, position the left ADC supplies the center ADIRU, in ALTN (alternate) position the right ADC supplies the center IRU. Data also comes from both left and right flight management computers as initialization inputs.
The L/R YAW DMPR test switch on the P61 panel will cause the left or right yaw damper module to go in to test. When either module is in test it sends an ADIRU test discrete to all three ADIRU’s.
Ground Warning
If ac power is lost and any ADIRU is on, the ground crew call horn will sound to warn personnel that the ADIRU is being powered from the airplane battery.
ADIRS OUTPUTS
Output Signals
The high speed ARINC 429 data buses transmit data from each ADIRU related to airplane heading, attitude, inertial velocities, position, acceleration, angular rates, and wind speed and direction. Status discretes route to the inertial reference mode panel and to the EICAS computers for display on the upper EICAS display unit.
Interfacing Systems
This sheet shows the ADIRU that provides data to each interfacing system. MMR Input for GPS initialization is provided on provisional aircraft.
ALTERNATE CAPT AND F/O’S CADC SELECT SWITCH
Features
An alternate CAPT / F/O’s SELECT guarded and wire-locked switch is provided to allow selection of Center ADIRU for CADC functions during Deferals.
When a Captains (Left) or F/O’s (Right) Air Data function is inop, ALTN can be selected to allow deferral of the Captains or F/O’s and the Center ADIRU would be used for indication. This switch has to be actuated prior to takeoff since it is located in the main equipment center at the outboard side of the E-1 Rack.
ALTERNATE VMO/MMO SELECT SWITCH
Features
An alternate VMO/MMO SELECT guarded and wire-locked switch is provided to accommodate a flight with the landing gear extended.
When a flight with the gear down is anticipated, this switch has to be actuated prior to takeoff since it is located in the main equipment center.
Actuation of this switch modifies the air data inertial reference unit software such that the maximum operating speeds allowed are greatly reduced. The specific values are provided on the graphic 767 MAXIMUM OPERATING SPEED SCHEDULE.
ALTERNATE VMO/MMO SELECT SWITCH
The ALTERNATE VMO/MMO select switch allows the
airplane to fly with the landing gear extended.
VMO = VELOCITY MAXIMUM OPERATING
MMO = MACH MAXIMUM OPERATING
ADIRS MESSAGES
General
The upper EICAS display unit on the EICAS panel announces the IRS ON DC, IRS DC FAIL, and IRS FAULT messages as a level C message. These messages appear at the same time as the amber annunciator lights on the IRMP.
REDUCED VERTICAL SEPARATION MINIMA
Purpose
Reduced vertical separation minima (RVSM) permits 1,000 foot separation between aircraft operating at altitudes from 29,000 to 41,000 feet inclusive. The operators must also have obtained the airworthiness approvals necessary to fly specific fleet type aircraft in RVSM designated airspace. Aircraft not complying will fly below RVSM airspace. As of January 20, 2005 RVSM airspace now covers all of North America, Canada and Mexico.
This reduced separation provides an additional six flight levels and increased airspace capacity.
Requirements
RVSM maintenance program is FAA governed and altimetry errors must be reported to the agency within 96 hours stating the irregularity and corrective action. Height keeping errors are monitored by the Aircraft Engineering department and the AD/Regulatory Compliance group. These two groups monitor aircraft logbook discrepancies for height keeping errors.
In order to qualify for RVSM, certain equipment must be installed on the aircraft. • There must be at least two independent altitude measuring systems (the
Captain and First Officers primary altimeters satisfy this requirement). • There must be at least one altitude reporting transponder.
• An altitude alerting system.
• An automatic altitude control system. Manual System
Refer to MEL for each aircraft type for RVSM compliance when deactivating any system that directly affects the RVSM airworthiness.
Maintenance of RVSM components is also a critical item. The aircraft illustrated parts catalog (IPC) may denote RVSM-Critical components versus a standard aircraft configuration.
The aircraft structural repair manual (SRM) will contain specific RVSM requirements to ensure proper maintenance of airframe geometry relative to repairs or alterations made in defined windows surrounding pitot/static probes, static ports, and AOA sensors.
The SRM will provide the limits for the following: • Skin waviness tolerances
• Aerodynamic smoothness tolerances • RVSM critical area dimensions • Static port height tolerances
• Pitot tube and combination probe alignment tolerances • Fastener height tolerances
• Bulge and skin contour limits in RVSM critical areas • Repair requirements in RVM areas
ANTENNA LOCATIONS
Weather radar antenna
The nose radome area contains the weather radar antenna (flat plate). Glide slope antenna
Left, right, & center
Two dual-element antennas are installed on the forward pressure bulkhead in the nose radome area
Localizer antennas Left, right, & center
Two dual-element antennas are installed on the forward pressure bulkhead in the nose radome area
ATC (Air Traffic Control) antennas Left & right
Two blade antennas are installed, one on upper and one on lower forward fuselage. (mode S)
DME (Distance Measuring Equipment) antennas Left & right
Two blade antennas are installed on the lower mid fuselage Radio altimeter antennas
Left, right, & center
Six surface mounted antennas are installed on the lower mid fuselage; 3 transmit and 3 receive antennas
Marker beacon antenna
The marker beacon antenna is installed on the lower mid fuselage
TCAS (Traffic Collision Avoidance System) antennas
Two directional TCAS antennas are installed, one on the top and one on the bottom of the forward fuselage
RADIO ALTIMETER - INTRODUCTION
General
The Radio Altimeter System provides accurate terrain clearance altitude information, displayed in the flight compartment, for use by the flight crew. It also provides input to interfacing systems where radio altitude is used in various computations or for the establishment of flight conditions required for warning annunciation’s.
The Radio Altimeter System consists of 3 identical Radio Altimeter Receiver / Transmitter (R/T) units with their associated equipment. All 3 R/T units operate simultaneously, independently from one another. The radio altitude is computed from the time interval a transmitted rf signal needs to travel to the ground and return to the airplane after reflection from the ground. The radio altimeter system operates at altitudes up to 2500 feet and is primarily used in approach, landing and take-off phases of flight. The system operates in the C-band, with a center frequency of 4300 MHz.
Inputs
Each R/T unit, located on the E5-1 rack in the mid-equipment center, transmits RF signals to the ground through a dedicated transmitter antenna. The
reflected RF signals are received by a dedicated receiver antenna and routed to the R/T units for altitude computation. All 3 transmitter antennas and all 3 receiver antennas are flush mounted on the forward bottom of the fuselage. Each R/T unit receives a discrete from an air/ground relay, to separate flight segments in the fault memory and to inhibit recording on the ground.
Outputs
Radio altitude output from the R/T units is transmitted to the captain's and first officer's radio altimeter indicators and both EFIS system EADI's for display, as well as to the using systems: autopilot flight director system (AFDS), EICAS, ground proximity warning system (GPWS) and the central warning system. Circuit breakers for all three radio altimeter systems are located on the P11 panel.
RADIO ALTIMETER COMPONENT LOCATIONS
Radio Altimeter System Components
The radio altimeter system comprises the following components that are located as follows:
• Left, center and right radio altimeter circuit breakers - located on overhead circuit breaker panel (P11).
• Transmitter antennas - located on bottom of the fuselage at station 577: LBL 14.1, BLO, RBL 14.1.
• Receiver antennas - located on bottom of the fuselage at station 621: LBL 14.1, BLO, RBL 14.1.
• Left, center and right receiver/transmitter units - located on rack E5-1 in the mid equipment center.
Interfacing System Components
The following interfacing systems components are associated with the radio altimeter system and are located in the flight compartment as indicated: • Left and right EFIS control panels - located on quadrant stand P10. • Left EADI - located on captain's instrument panel P1.
• Right EADI - located on first officer's instrument panel P3.
Air/ground relay K124 - for left radio altimeter receiver/transmitter, located in left miscellaneous electronic equipment panel (P36).
Air/ground relay K293 - for center radio altimeter receiver/transmitter, located in right miscellaneous electronic equipment panel (P37).
Air/ground relay K214 - for right radio altimeter receiver/transmitter located in right miscellaneous electronic equipment panel (P37).
RADIO ALTIMETER DISPLAYS
General
On the electronic attitude director indicator, the radio altitude and the decision height are displayed in the right-hand top corner.
Radio Altitude and Decision Height Display
Radio altitude is displayed for altitudes between -20 and 2500 feet. The readout is white, in feet. In addition, if the EFIS "ILS" mode is valid and below 200 feet radio altitude, the green rising runway symbol displays radio altitude by moving up toward the fixed airplane symbol until touchdown. For altitudes above 2500 feet, the readout is blank.
The decision height is displayed above the radio altitude display. The readout is in green and consists of the letters "DH" followed by the selected decision height value in feet between 0 and 999 feet radio altitude. If a negative decision height value is selected, the "DH" display is blanked.
Decision Height Alert and Alert Termination
As the airplane descends through the selected decision height value, the radio altitude readout changes from white to yellow, and the green decision height display changes to the large yellow letters "DH". During the first 3 seconds, the letters "DH" blink.
At reset, the display returns to the normal readout: the radio altitude changes back to white, and the yellow "DH" readout is replaced by the green letters "DH" followed by the selected decision height value.
No-Computed-Data (NCD) and Invalid Data
In the event of no-computed-data, the radio altitude readout is replaced by 4 white dashes. The decision height readout for no-computed-data is replaced by the yellow letters "DH" inside a yellow outline box.
Invalid data is indicated by the yellow letters "DH" and "RA", respectively, each inside a yellow outline box.
Decision Height Alert Termination (Reset)
The decision height alert can be terminated automatically or manually.
Automatic reset occurs at touchdown, or when the airplane climbs to a height 75 feet above the selected decision height. Manual reset is achieved by actuating the reset push-button switch "RST" on the EFIS control panel.
Radio Altitude Tape
The functions of the radio altitude tape indicator are to indicate radio altitude, to set the decision height (DH) and to display DH" alert.
The radio altitude tape indicates the airplane altitude above ground. The altitude range is from 0 to 2500 feet. The altitude scale is linear from 0 to 500 feet, and logarithmic from 500 to 2500 feet.
Decision Height Selection
A decision height can be selected within the range from 0 to 499 feet by means of the decision height set knob. The knob sets the decision height index to the selected value, which then is displayed on the three-digit decision height display. The decision height selected and the annunciation on the radio altitude indicator is independent of the one selected on the EFIS control panel. The decision height setting from both radio altitude indicators (higher of the two if different) is an input to the ground proximity warning computer (GPWC) for the mode 6 alert "MINIMUMS-MINIMUMS".
Decision Height Alert and Reset
A decision height alert is annunciated by the illumination of the "DH" light/switch whenever the radio altitude is less than the selected decision height value. The decision height alert can be reset by pushing the "DH" light/switch. It also is reset automatically when the airplane rises to a radio altitude equal to the decision height value + 15 feet.
Fault Annunciation
The failure flag drops in view for invalid data code or functional test code in the sign-status matrix of the received radio altitude word (ARINC 429), for power supply faults or for malfunction of the indicator internal circuits.
RADIO ALTIMETER SELF TEST
Self-Test Initiation
The manual self-test is initiated by pressing the TEST switch on the transmitter/ receiver front panel. For a complete test, the switch must be held down for at least six seconds. Automatic self-tests are performed at power-on and at regular intervals during normal operation.
Manual self-test capability is inhibited in flight. T/R Unit Status Indicators
Upon self-test initiation all four front panel status indicators illuminate for three seconds. After the three seconds, the status indicators extinguish for a three-second interval. Subsequently, the green LRU STATUS PASS indicator illuminates for proper system operation. In the event of a fault, the respective red fault indicators illuminate, and the green LRU STATUS PASS indicator remains off. Either LED remains on until the TEST switch is released.
A program exists which provides for the red LRU STATUS FAIL light to come on during self-test in the event of past fault occurrence during the last four flights. This program has several options and is reserved for implementation by the airline. Instructions are obtainable from the vendor representative.
EADI Display
While the test switch is depressed, the EADI indicates a radio altitude of 40 +/- 1 1/2 feet.
Automatic Self-Test
No special test indications are associated with automatic self-tests. If no failures are detected during the automatic self-tests, the operation of the system proceeds normally. If a fault is detected, the fault is annunciated by a yellow RA flag on the EADI.
ALTITUDE ALERT - COMPONENT INTERFACES
Purpose
The system advises the pilots when the airplane approaches within 750 feet of a preselected altitude and when the airplane departs a distance greater than 250 feet from a preselected altitude.
AFCS Mode Control Panel
This panel provides the means for the pilots to input a selected altitude into the AFCS and altitude alert system.
Air Data Inertial Reference Units
These units provide barometric altitude reference data to the altitude alert system.
Proximity Switch Electronics Unit
This unit sends a landing gear up/down signal. Parking Brake Switch
The set or released status signal is provided by this switch. Visual
The visual indications output by this system are: amber master caution lights, the amber ALT ALERT light, the two white ALT lights on the captain's and F/Os altimeters, the level B message ALTITUDE ALERT on the upper EICAS display.
Aural
A level B caution aural sound (beep-beep-beep) is heard over both aural warning speakers for 0.8 seconds.
General Operation
Following the selection of a desired altitude, various visual indications and aural sounds occur as the airplane approaches and later deviates from that altitude. Altitude alerting occurs at certain specific distances from the selected altitude during the approach mode and deviation mode. The specific distances are described later.
ALTITUDE ALERT OPERATION
Operational Sequence
When the airplane approaches the selected altitude and is within 900 feet above or below the selected altitude, visual signals are generated by the altitude alert module. The ALT advisory lights on the captain's and first officer's altimeters illuminate. As the airplane continues toward the selected altitude, and passes through 300 feet from the selected altitude, the ALT advisory lights extinguish. As long as the airplane flies within the 300 feet of the selected altitude, no further indications are produced.
If the altitude deviation subsequently exceeds 300 feet, the following aural and visual indications are produced:
• The aural warning speakers sound the level B caution aural
• The amber ALT ALERT light and the master caution lights illuminate • The ALTITUDE ALERT caution message is displayed on the EICAS
Display Unit (upper)
When the pilot changes the selected altitude or when the airplane deviates more than 900 ft from the selected altitude, the caution signals are canceled and the microprocessor is reset to the approach mode. The caution signals are inhibited, in flight, when the landing gear is down and locked. This action prevents nuisance caution indications during the approach phase. The caution signals are also inhibited when the airplane reenters the +/-300 foot envelope above or below selected altitude.
If the airplane is on the ground with the parking brake set, the caution signal inhibits are removed so that the altitude alert system can be tested.
ALTITUDE ALERT OPERATIONAL CHECKOUT
Test Preparations
The functional test is accomplished on the ground (landing gear down and locked, parking brake set) by using the mode control panel's altitude select knob to simulate an altitude difference in order to check the approach and the deviation modes.
Operational Checkout
To test the system, slowly rotate the altitude select knob away from the airplane baro altitude as seen on the captain's electric altimeter. Then turn the altitude select knob to approach the airplane baro altitude. Monitor correct operation. Continue rotating the altitude select knob so the error reduces to zero and then increases beyond the deviation threshold. Monitor correct operation.
Use the graphic for the appropriate altitude setting and annunciation’s. To enable the master caution lights during test, remove the EICAS engine shutdown input (reference MM 31-41-00). For the level B message ALTITUDE ALERT, the level B aural is not inhibited.
INTEGRATED STANDBY FLIGHT DISPLAY (ISFD)
COMPO-NENT LOCATION
General
The integrated standby flight display (ISFD) is located on the captains P1 Panel. The ISFD battery charger is located in the E1 rack.
INTEGRATED STANDBY FLIGHT DISPLAY TEST
General
The integrated standby flight display is tested by pushing both the APP and HP/ IN switches together to enter the maintenance mode display. Then push the “TEST” key to enter the maintenance testing menu or “Other Data” to enter other elements of the submenus of the ISFD.
ELECTRONIC FLIGHT INSTRUMENT SYSTEM (EFIS)
General
The EADI's and EHSI are used to display flight and navigation information which includes certain ADIRU data. Attitude and ground speed are shown on the EADI. Track, heading and wind are shown on the EHSI.
The on side (or center if selected) ADIRU is always used by the EFIS symbol generator for attitude and heading displays. Normally the FMC (which uses one or three ADIRU’s) is used by the EFIS for track, ground speed and wind. When the FMC calculated data are invalid, the on side or selected ADIRU is used by the EFIS for track, ground speed and wind displays.
FMC Calculations
The FMC uses inputs from the navigation radios and ADIRU’s to independently calculate ground speed, track and wind vector. The FMC uses North velocity, East velocity and heading from the ADIRS, and true airspeed (TAS) from the ADIRUs. It uses latitude and longitude from radio position data.
For use in its calculations, the FMC first determines the total velocity vector which is based, in part, on the average of the ADIRU’s North and East
velocities. If a velocity from one IRU differs from the average by more than 20 knots, the FMC ignores that ADIRU, and uses a single ADIRU (on side or center if selected) to calculate the total velocity vector. Ground speed and track are calculated from the total velocity vector.
To calculate the wind vector, the FMC uses its ground speed and track
calculations, TAS and heading from the ADIRS. The FMC uses heading from a single ADIRU which corresponds to the autopilot in command. If no autopilot is in command, the left-most available ADIRU is used.
Track
When the airplane is in the air, the EFIS normally uses the FMC calculated value of track for display. If the FMC track is invalid, EFIS will use track from its on side or selected ADIRU. When the airplane is on the ground (ground speed less than 50 knots), EFIS uses heading from the on side or selected ADIRU and displays it as track (track and heading are always the same on the ground). If the on side ADIRU fails in flight, the other ADIRU’s continue to provide valid data to the FMC, which provides valid track to the EFIS symbol generators. The EFIS will continue to show a valid map display (except the heading bug is missing). If the on side ADIRU fails on the ground, the map display will show the MAP and TRK flags because the EFIS uses the heading from the on side (which is invalid) ADIRU as a substitute for track.
Ground Speed
Normally the EFIS uses the FMC for the ground speed display. If the FMC is not valid the EFIS uses the on side or selected ADIRU for the ground speed display.
Wind
Normally, the EFIS uses the FMC for the wind direction and speed display. If the FMC is not valid the EFIS uses the on side or selected ADIRU.
Heading and Attitude
The EFIS always uses the on side or selected ADIRU for heading and pitch and roll attitude display.
EFIS - INTRODUCTION
General
The flight instrument system provides displays for most of the airplane navigational systems.
Subsystems included in the flight instrument system are: Electronic Flight Instrument System (EFIS)
EFIS includes the electronic attitude director indicators (EADI’s), electronic horizontal situation indicators (EHSI’s), EFIS symbol generators, and EFIS control panels.
Radio Distance Magnetic Indicators (RDMI’s)
The RDMI’s display airplane heading navigational distance, an d directional bearings.
Vertical Speed Indicators (VSI’s)
For display of vertical climb and descent rates as sensed by the Air Data Inertial Reference System (ADIRU’s).
Instrument Source Select Switches
EFIS COMPONENT LOCATIONS
EADI’s (2) and EHSI’s (2)
Located directly in front of the captain and first officer on P1 and P3. Instrument Source Select Switches
Located on the instrument source select panels on the outboard edges of P1 and P3.
EFIS Control Panels
Separate panels for the captain and first officer are located on the left and right side of P10.
The Left, Right and Center EFIS Symbol Generators Located on equipment rack E1.
Remote Light Sensors
Two forward-sensing sensors are located on the glare shield panel P7.
(Additional ambient light sensors are integrally mounted on the front faces of the EADI’s and EHSI’s.)
HDG REF Switch
Located on first officer's instrument panel P3-1. EFIS SYMBOL GENERATOR
The EFIS symbol generator processes data from the EFIS control panel and navigation and guidance systems to provide video signals to the EADI and EHSI display CRTs.
Front Panel
The momentary TEST switch initiates the self-test for checking the symbol generator, display units, and control panel. The momentary RESET switch erases the faults stored in memory. The RESET function is not used on the new-generation symbol generators.
EFIS CONTROL PANEL
Purpose
The EFIS control panel controls displays on the EADI and EHSI, allows selection of decision height, and enables the weather radar system. Switch Functions
EADI Controls:
• BRT - controls brightness level of EADI display.
• DH REF - these LCD’s display the selected decision height.
• Decision height set knob - this 24-detent, continuous-turn control knob sets the decision height. The range for decision height is -20 to +999 feet. At selection below zero feet the DH display on the EADI is removed. Decision height starts at 200 feet, as a baseline, when power is applied, and corrected by turning the DH set knob. Two speeds of response are achieved by software.
• RST - manually resets the decision height circuits after the airplane has passed through decision height. EHSI Controls:
• RANGE - selects the range for the weather radar and navigation data displayed on the EHSI.
• TFC - enables TCAS traffic data on the EHSI in MAP, VOR, or ILS modes. • Mode select switch - selects mode of data on the EHSI display. The
modes display 70 degrees arc, with the airplane symbol at the bottom of the display on all modes except the PLAN mode. The CTR (center) MAP switch allows the selection of a center map display as well as a full ILS or full VOR display.
Note: In the PLAN mode, actuation of CTR map switch is mechanically inhibited.
• BRT - these are two concentric knobs. The outer controls the overall brightness of the EHSI display; the inner controls the relative brightness of the weather radar display.
• WXR - this push-on/push-off switch turns on the WXR XCVR and enables the display of weather radar information on the EHSI during the MAP, VOR, or ILS modes. No weather radar data is displayed during PLAN mode. The white band around the rim is visible only in the OFF position.
• MAP display switches - during MAP - mode, these switches cause the display of the symbols listed below. Any or all MAP display switches may be actuated at the same time. The switches are push-on/push-off and illuminate when actuated. The white band around the rim of each cap is visible only in the OFF position.
• NAVAID - VOR, VORTAC, etc. • ARPT - airports
• RTE DATA - waypoint altitude and estimated time-of-arrival • WPT - waypoints not in the selected flight plan
INSTRUMENT SOURCE SELECT PANELS
Purpose
These two panels allow the pilots to connect to their alternate data sources. The captain and first officer can make selections independently of the other. The ALTN switch illuminates when the alternate source has been selected. Switch Functions
• FLT DIR Switch - This switch connects the left, center, or right flight control computer to the flight director portion of display on the EADI. • FMC Switch - This switch selects the left or right flight management
computer (FMC), or the on side control display unit (CDU), as the source of navigation and flight parameters for the EHSI display. It is also used to select the source for display on the on side FMC CDU. The switch on the Captain's side only is also used to determine which FMC is the source of the VOR/DME autotune frequency. When FMC-R or CDU-L are selected, the right FMC is the autotune source.
Note: Normally, the CDU-L position is not selected unless both FMC’s are faulty.
• EFI Switch - The EFI switch determines if the on side (normal) or the center (alternate) symbol generator supplies the video presentation on the EADI and EHSI. The captain's and first officer's EFI switches are
interlocked electrically such that if both are using the ALTN position, the captain's EFIS control panel and instrument source select switches have control of the center EFIS symbol generator, and the INSTR switch level B EICAS message is initiated.
• IRS Switch - This switch determines which IRU provides data to the on side EFIS symbol generators, and VSI’s, the offside RMI’s, weather radar transceiver(s), the digital flight data acquisition unit (captain's switch only), and the antiskid/autobrake system. The right IRS instrument source select switch also determines if the center IRU receives air data inputs from the left or right air data computer. The on side IRU is normal; the center IRU is alternate.
AIR DATA Switch - Each AIR DATA switch selects air data inputs to the on
side or center EFIS symbol generators, on side mach/airspeed indicator, on side electric altimeter, ATC transponder and inertial reference unit. The left switch also selects the altitude source to the altitude alert module and flight recorder.
