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1.6.1 DISPLAY CONTROLLER
FULL/ARC: The FULL/ARC button is used to change the EHSI
display from full compass rose display to a partial compass display format. Successive pushes of the button change the display format back and forth between FULL and ARC.
WX (Weather): The WX button is used to call up weather radar
returns on the partial compass display. If the EHSI is in the FULL display format, selecting the WX display will automatically select the ARC format. A second push of the WX button will remove the weather information but the ARC format will remain.
GS/TTG: By pressing the GS/TTG button, Groundspeed or the
Time-to-GO will be displayed alternately in the lower right corner of the EHSI.
ET: By pressing the ET button, Elapsed Time is displayed. If the ET button is pressed again, it will zero the
displayed time. The sequence is:
1. Zero.
2. Start.
3. Stop.
MAP: By pressing the MAP button, the full compass display
is changed to the partial compass display, with active Waypoints displayed. Also, VOR/DME ground station positions will be displayed.
SC/CP: By pressing the SC/CP button, the flight director
command cues are toggled back and forth from single cue (SC) configuration to cross pointer (CP)
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REV: In the event of an EADI/EHSI display failure, the REV
button may also be used to display a composite format on the remaining good display. The first push of the button will blank the EHSI and put the
composite display onto the EADI. The second push blanks the EADI and puts the composite display onto the EHSI. A third push will return EHSI/EADI to normal.
CRS Select Knob: Rotation of the Course select knob allows the course pointer on the EHSI to be rotated to the desired course.
DIM: Rotation of the outer concentric DIM knob allows the
overall brightness of the EADI, EHSI to be adjusted. After the reference levels are set, photoelectric sensors maintain the brightness level over various lighting conditions.
DH: Rotation of the inner concentric DH knob allows the Decision Height, displayed on the EADI, to be
adjusted. If the knob is rotated fully counterclockwise, the DH display is removed.
TEST: By pressing the TEST button, the displays will enter
the test mode. In the test mode, flags and cautions are presented along with a check of the flight director mode annunciations. If the test is successful a “PASS” is displayed. If the test is unsuccessful then an “FD FAIL” is annunciated.
RASTER DIM TOP/BOT: Rotation of the outer (Bottom display) and inner (Top display) concentric knobs adjusts the raster scan display (Weather Radar and Attitude Sphere).
HDG: Rotation of the heading select knob allows the
heading select bug to be rotated to the desired heading.
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1.6.2 SOURCE CONTROLLER
Used to select the available sources of heading, attitude, bearing and
navigation information for display. Since each aircraft is different, the source controller is normally tailored to fit each need.
NAV: This button is used to control the source of VHF NAV
display information. Each push of the button will toggle the source between pilot and copilot’s NAV information. VHF systems include DME, ILS and VOR.
LRN: Long Range Navigation selections depend on the
systems available. These include INS, VLF and FMS systems.
ATT: Attitude button selects the source of attitude
information. Each push of the button will select a different source for display. This facility is not available on all aircraft.
BRG: This knob allows the selection of VOR and ADF
bearings to be displayed. The selected source is annunciated on the left-hand side of the display and the bearing to the selected beacon via two bearing pointers.
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1.7 ELECTRONIC INSTRUMENTS (ENGINE & AIRFRAME)
The display of the parameters associated with engine performance and airframe systems control, by means of CRT type display units has, like those of flight instrument systems, become a standard feature of many types of aircraft.
The display units form part of two principal systems designated as:
1. Engine Indicating and Crew Alerting System (EICAS).
2. Electronic Centralized Aircraft Monitoring (ECAM).
1.8 ENGINE INDICATING & CREW ALERTING SYSTEM
The basic system comprises two display units, a control panel and two computers supplied with analog and digital signals from the engine and system sensors. The computers are designated “Left” and “Right” and only one is in control of the system at any one time, the other is held in standby. In the event of a failure, it may be switched in either manually or automatically.
Operating in conjunction with the system are discrete caution and warning lights, standby engine indicators and a remotely-located panel for selecting
maintenance data display. The system provides the flight crew with information on primary engine parameters (Full-time), with secondary engine parameters and advisory/caution/warning alert messages displayed as required.
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1.8.1 DISPLAY UNITS
These units provide a wide variety of information relevant to engine operation, and operation of other automated system. The operation of these displays is as for those in the EFIS as previously described.
The upper unit displays primary engine parameters, i.e. N1 speed, EGT, and warning and caution messages. The lower unit displays secondary parameters, i.e. N2 speed, fuel flow, oil quantity, pressure and temperature. In addition, the status of non-engine systems e.g. flight control surface position, hydraulic system, APU, etc., can be displayed.
On the upper unit, a row of Vs will appear when secondary information is being displayed on the lower unit. Seven colours are produced by the CRTs for displaying information. Table 1 shows the colours and a description of their use.