AIRCRAFT Electronic Instrument Systems

Introduction: Instruments have a vital role in controlling aircraft They are means of communicating data between the aircraft systems and the controller (the Pilot) Content and format of data displays are standard. Why? For easier control and less mental effort

Common forms of Displays Quantitative Qualitative

Quantitative Displays: Data is presented in terms of a numerical value and by the relative position between a pointer or index and a graduated scale Example: An Airspeed Indicator

Data is presented in pictorial or symbolic format Qualitative Displays Data is presented in pictorial or symbolic format Example: Attitude Director Indicator

Instrument Panels and Layouts Primary Data must be in the pilot’s line of vision Indications are so coordinated as to create a ‘picture’ of the aircraft flight condition Important for instruments to be properly grouped to maintain coordination Must assist pilot in observing them with minimum effort

Vertical Speeded Indicator The ‘Basic Six’ Layout Airspeed Indicator Gyro Horizon Altitude Indicator Turn & Bank Indicator Vertical Speeded Indicator Direction Indicator

The Basic ‘T’ layout Attitude Director Indicator Altitude Indicator Mach & Airspeed Indicator Vertical Speed Indicator Radio Magnetic Indicator Horizontal Situation Indicator

Types of Indicators Analogue Indicators Electronic displays Mechanical Instruments showing a pointer moving on a dial or scale. Used mainly in older generation Aircraft Electronic displays Instrumentation in the form of a CRT or LCD display. Used in modern Aircraft

Example of an Analogue Instrument: An Analogue Altimeter which indicates ‘Altitude’

Example of an Electronic Instrument: Electronic Attitude Director Indicator (EADI) or Primary Flight Display. It also displays Altitude and Airspeed

Another example of an Electronic Instrument: Electronic Horizontal Situation Indicator (EHSI) or Navigation Flight Display. It also displays Weather information

Boeing 737-200 Cockpit – all instruments are analogue The Analogue Cockpit Basic T-displays Boeing 737-200 Cockpit – all instruments are analogue

Airbus A320 cockpit – Almost all instruments are digital displays The ‘Glass’ Cockpit Basic T layout display Airbus A320 cockpit – Almost all instruments are digital displays

Airbus A340 cockpit – Almost all instruments are digital displays Basic T layout display Airbus A340 cockpit – Almost all instruments are digital displays

Boeing 737 ‘New Generation’ Glass Cockpit Basic T layout display Boeing 737 ‘New Generation’ Glass Cockpit

Another Glass Cockpit – The Boeing 747 modern generation aircraft Basic T layout display Another Glass Cockpit – The Boeing 747 modern generation aircraft

Major difference between cockpits Analogue Basic T-layout consists of separate analogue instruments Separate T-layout for Pilot and Co-pilot Glass Basic T-layout grouped in 2 CRT’s One common T-layout spread on whole instrument panel

Electronic Instrument Systems All modern aircraft use electronic display devices EIDS (Electronics Instrument Display Systems) EFIS (Electronic Flight Instrument Systems) Highly sophisticated technology providing the pilot with attitude and navigation information

Electronic Instrument Systems Divided into two main sections: Electronic Flight Instrument System (EFIS) Aircraft and System Monitoring Instrument System

Basic Aircraft EFIS System

The Airbus A320 EIS Cockpit Layout MCDU ND or EHSI – Displays Nav. Info. And Weather PFD or EADI – Displays Attitude, Airspeed, Altitude, etc. ECAM system displays Printer The Airbus A320 EIS Cockpit Layout

Features of the EIS system All is controlled by a Central Processing Unit (Data Management Unit) Parameters, Error messages and maintenance data can be retrieved via MCDU or a Printer Data filtering: Important data accentuated; temporary unimportant suppressed Information can be transferred from one monitor to another

More features and advantages of EIS systems Variability and Variety Coloured Displays All monitors/displays for the system are the same (ie: less components needed) Brightness controlled automatically depending upon the level of sunlight Data can be sent via Radio to ground (ACARS – Arinc Communication Addressing and Reporting Systems)

One disadvantage however: In bright sunlight it might be more difficult to read monitor indications than it was with analogue indicators.

Monitoring systems Part of Electronic Instrument System: On Airbus: ECAM system (Electronic Centralized Aircraft Monitoring) On Boeing: EICAS system (Engine Indication and Crew Alerting System)

ECAM system: Monitors aircraft functions and relays them to the pilots Produces messages detailing failures In certain cases lists procedures to undertake to correct problems Colour coded warning scheme helps pilots to instantly assess the situation ECAM system:

EFIS/ECAM system components (Airbus) Engine/warning CRT CRT control and transfer PFD ND System/Status CRT ECAM Control Panel MCDU EFIS/ECAM system components (Airbus) Printer

The Engine/Warning CRT Display shows: Engine Parameters Fuel on Board Flight Control position Warning/caution messages Memo (when no failure exist)

System/Status CRT Display shows: System synoptic diagrams Status messages

The ECAM Control Panel Allows selection of system/status pages Suppression and recall of warning/caution messages Pressing ‘ALL’ will allow successive presentation of all system pages.

The MCDU and Printer MCDU (Multifunction Control & Display Unit) The heart of the A320/319. Everything that the airbus can do, can be controlled from this unit, including Maintenance Tests. Aircraft Performance Data as well as Maintenance Data can be printed on a Printer.

CRT switching Data can be transferred between displays Very useful in the case of CRT failure

EICAS system: Provide aircraft engines parameters such as RPM, temperature values, fuel flow, etc. Monitors systems like hydraulic, air-conditioning, electrical, etc. Generates crew annunciations and warnings.

EFIS/EICAS System Components (Boeing) EICAS Caution and Annunciation Panel Engine Primary Display Engine Secondary Display or Status/Maintenance Display CRT switching Control Panel EFIS/EICAS System Components (Boeing)

EICAS Display Units Engine Primary Display and Warning Display Engine Secondary Display and Status/Maintenance Display

EICAS Warning and Caution Annunciation Panel

ECAM/EFIS/EICAS Display MESSAGE Colour Coding: RED: Warning AMBER: Caution GREEN: Normal Operation BLUE: Action to be carried out In addition to the CRT display, warnings and cautions generate an attention getter and audible sound in the cockpit.