Avionics Chpt 6

• Electronic Flight Instrument Systems (EFIS) comprise 2 identical systems:

  • Upper display screen - Electronic Attitude & Direction Indicator (EADI)
  • Lower display - Electronic Horizontal Situation Indicator (EHSI)

  Each pilot’s display has its own control panel & a symbol generator from which the electronic representations on the screens are generated
• Electronic Flight Instrument Systems (EFIS):

  • A third symbol acts as a standby unit in case of failure
  • Each symbol generator receives inputs from both internal & external navigational sources
  • Display screen to present the information in a standard format
• Electronic Flight Instrument Systems (EFIS):

  • The symbol generators perform the monitoring & control functions of the EEIS
  • The control panel is used to control the EADI, EHSI display
  • The remote light sensor automatically adjusts the brightness of the screen display according to the light level on the flight deck
• Electronic Attitude & Direction Indicator (EADI):

  • Displays aircraft attitude in pitch & roll in the conventional format of artificial horizon divided horizontally, with the upper half coloured blue & lower half coloured yellow
  • The source data for the attitude indication are the aircraft inertial reference systems
  • The display also includes flight director command bars, ILS glideslope & localizer deviation indications, & deviation indications from a selected airspeed
• Electronic Attitude & Direction Indicator (EADI):

  • Radio altitude, decision height & operating modes of the automatic flight and auto throttle systems are also displayed on the EADI screen
• Electronic Attitude & Direction Indicator (EADI):

  • Between 1000 ft & 2500 ft, radio altitude is displayed in digital format only, but below 1000 ft Above Ground Level (AGL) the display changes to analog format
  • The decision height (DH) can be set by a control knob on the EFIS control panel & the selected DH is digitally displayed on the EADI screen
  • At 50 ft above DH aural chime begins to sound
• Display features should be colour coded as follows:

  • Warning - Red
  • Cautions - Amber
  • Earth - Brown
  • Sky - Blue
  • Engaged modes - Green
  • ILS deviation pointer - Magenta
  • Flight director bar - Magenta/Green
• Precipitation & predicted turbulence areas should be colour coded as follows - Precipitation (mm/hr):

  • 0 to 1 - Black
  • 1 to 4 - Green
  • 4 to 12 - Yellow
  • 12 to 50 - Red
  • Above 50 - Magenta
  • Turbulence - White
• Electronic Horizontal Situation Indicator (EHSI):

  • Presents a display of flight navigational information & progress in 1 of 9 possible modes
• EHSI mode:

  • MAP - The display used for en-route navigational information & the one most commonly selected in cruise flight
  • The display shows features ahead of the aircraft, with the aircraft symbol appearing at the bottom of the display
• EHSI mode:

  • CTR MAP - Essentially the same as MAP, but the display is centred upon the aircraft current position
• EHSI mode:

  • PLAN - This display shows the planned route with waypoints and is principally used when entering waypoints into the Flight Management System (FMS) computer before flight or when making changes to the planned route
• EHIS mode:

  • FULL VOR/FULL ILS - These displays are identical & show a compass rose with heading & deviation indications that follow conventional formats
  • They are used when checking aircraft track against a VOR bearing or ILS localizer
• EHIS mode:

  • EXP VOR/ILS - In the expanded mode the information displayed is the same as in the full mode, but is in semi-map format
• EHIS mode:

  • EXP NAV/FULL NAV - These two modes display lateral & vertical navigational information in the same format as conventional HSI
  • Expanded NAV mode shows a compass arc, whereas full NAV mode displays a full compass rose & does not permit the weather radar display to be superimposed, exactly with the expanded and full VOR/ILS modes
• Engine Indication & Crew Alerting System (EICAS):

  • An electronic display consisting of 2 CRT screens mounted vertically, 1 above another, where they are easily visible to either pilot
  • The displays are capable of presenting all the engine & system operating data
• Engine Indication & Crew Alerting System (EICAS):

  • Upper screen - primary display, shows only essential engine information: Engine Pressure Ratio (EPR), Turbine Fan Speed (N1) & Exhaust Gas Temperature (EGT)
  • Lower display - secondary display, displays less important information & details of abnormal engine operating conditions
• The EICAS displays are generated by 2 computers that are continuously receiving operating data from the engines. A display selection panel enables the pilot to select 1 of the 2 pages such as OPERATONAL & MAINTENANCE Pages.
• Operational Page:

  • This mode is used throughout flight in which the upper screen displays the primary engine information & lower screen remain blank so long as all engine & system operation parameters are normal
  • In the event of abnormal conditions, an alert message will appear on the upper screen & lower screen will display details of abnormal condition
• Maintenance Page:

  • This mode is available to maintenance engineers for diagnosis of operating faults. It contains records of engine & system operating conditions & is only available with the aircraft on the ground
• Aeronautical Radio Incorporated (ARINC):

  • Is a global corporation consists of various US, international airlines, aircraft operators & their subsidiaries to provide services related to a variety of aviation communication & navigation systems
• Aeronautical Radio Incorporated (ARINC):

  • Provides standardization guidelines for engineering & development of both software & hardware systems for variety of military & civil aviation electronic systems
  • Responsible for 2 of the most common data bus standards used on transport category aircraft (ARINC 429 & 629)
• Built In Test Equipment (BITE):

  Designed to provide fault detection fault isolation & operational verification after defect repair

  • Fault detection is performed continuously during system operation
• Built In Test Equipment (BITE):

  • If a defect is sensed, the BITE initiates an appropriate control signal to isolate any defective components
  • In order to repair the defective system, the engineer can utilize the BITE to identify faulty components or wiring
• Built In Test Equipment (BITE):

  • The majority of the aircraft digital systems contain several line replaceable Units (LRU)
  • Defective LRU’s may be quickly identified by the BITE system & exchanged during ground maintenance
• Use of LRU & BITE concepts greatly reduce aircraft maintenance down time. Systems that employ dedicated BITE on the B747 include:

  • Engine Indication & Crew Alerting System (EICAS)
  • VHF & HF Communication Radio
  • Radio Altimeter
  • ATC transponder
  • Instrument Landing System
  • VHF Omni Range
  • Fire & Overheat
  • Fuel Quantity
  • Auto Brake
  • Window Heat
  • Hydraulic Management
  • Distance Measuring Equipment
  • Air Data Computer
  • Weather Radar
  • Automatic Direction Finding
  • Passenger Address
• • The advanced BITE system found on Airbus is known as Electronic Centralised Aircraft Monitoring (ECAM)
• The ECAM display screens are mounted side-by-side & both are in use continuously:

  • The left screen displays information covering systems status, warnings & corrective actions required in checklist format
  • The right screen shows associated information in analog displays

  The ECAM control panel consists of left & right display control knobs for switching on the displays and adjusting the display brightness.
• The system has 4 operating modes:

  • NORMAL
  • ADVISORY
  • FAILURE
  • MANUAL
• Normal mode:

  • This mode is flight-related & is the mode in which the system normally operates throughout the flight process from pre-flight through to post-flight checks
  • In this mode the left screen displays system states in checklist format & right screen contains a relative pictorial display
• Advisory mode: The display automatically switches to this mode when the status of a system changes
• Failure mode:

  • Automatically selected by the ECAM system in the event of normal operating parameters being exceeded on the left screen, accompanied by an aural alert
  • Below this message, the corrective actions required by the flight deck crew are listed
  • On the right screen a diagrammatic display of the affected system illustrates the fault. When the corrective actions have been taken the display changes to illustrate new status
• Manual mode:

  • If there are no warning messages displayed on the left screen, diagrams related to the aircraft systems can be called up on the right screen
• Flight Management System (FMS):

  • Almost all modern passenger transport aircraft employ a computerised FMS
  • To reduce crew work-load, & achieve the best possible fuel economy with overall result that operating coasts are minimised
• The FMS guides the navigation of the aircraft

  vertically (VNAV) to achieve the planned altitude at

  each waypoint of the planned flight & laterally

  (LNAV) to arrive overhead each geographical

  waypoint of the planned flight
• To perform its multitudinous functions, the FMS must be provided with navigational data from all the navigation systems:

  • Inertial Reference System (IRS)
  • Distance Measuring Equipment (DME)
  • VHF Omni Range (VOR)
  • From all the engine associated systems
• The link between the flight crew and FMS is Control Display Unit (CDU). It provides the crew with the means to make inputs to the system to obtain required display to assist with decision-making in respect to the aircraft’s flight progress
• CDU consists of:

  1. Display Screen:

  • Typically 2 x 3 in CRT screen - screen has 14 lines with total of 24 per line
• CDU consists of:

  2. Line Select keys: Momentarily depressing a line select key will select or delete the data
• CDU consists of:

  3. Annunciators: There are 2 annunciators on each side of the keyboard will display:

  • FAIL: The amber light illuminates when there is fault in the FMC
  • MSG: The white light illuminates to indicate to the pilot that FMC generated message is displayed on the scratchpad