Electronic & Digital Aircraft Systems I Quiz

Typical Electronic/Digital Aircraft Systems I (5.15)

• Learning Objectives: This section details the learning objectives for the study of typical electronic and digital aircraft systems. The objectives encompass describing general arrangements and Built-In Test Equipment (BITE) testing capabilities for various systems.

• Aircraft Communications Addressing and Reporting System (ACARS) (5.15.1.1): Describes the general arrangement and BITE testing features of ACARS, operating at Level 2.

• Electronic Centralised Aircraft Monitoring (ECAM) system (5.15.1.2): Explains the general arrangement and BITE testing for the ECAM system, also at Level 2.

• Electronic Flight Instrument System (EFIS) (5.15.1.3): Covers the general arrangement and BITE testing capabilities of the EFIS system, for Level 2.

• Engine Indicating and Crew Alerting System (EICAS) (5.15.1.4): Discusses the general arrangement and BITE testing capabilities of the EICAS, at Level 2.

• Fly-By-Wire (FBW) control system (5.15.1.5): Includes the general arrangement and BITE testing capabilities of FBW, operating at Level 2.

• Flight Management System (FMS) (5.15.1.6): Examines the general arrangement and BITE testing of the FMS, at Level 2.

• Global Positioning System (GPS) (5.15.1.7): Details the general arrangement and BITE testing capabilities of GPS, at Level 2.

• Inertial Reference System (IRS) (5.15.1.8): Describes the general arrangement and BITE testing of the IRS, at Level 2.

• Traffic Alert and Collision Avoidance System (TCAS) (5.15.1.9): Outlines the general arrangement and BITE testing capabilities of TCAS, at Level 2.

Integrated Test Equipment (ITE) (Aircraft Diagnostics)

• BITE (Built-In Test Equipment): Aircraft diagnostics now use self-diagnostic systems, which are known as BITE. This enables troubleshooting of complex digital systems.

• LRU (Line Replaceable Unit) Housing BITE: This describes the placement and function of BITE modules within the LRU housings of an aircraft.

BITE Systems

• BITE Configurations: Various types of BITE exist, ranging from simple go/no-go indicators (LEDs) to complex systems with multiple LRU testing capabilities and data display.

• Centralized Monitoring: Modern BITE systems utilize a centralized monitoring system for fault detection and data transmission to maintenance facilities through the flight.

BITE Information

• Boeing CMCS (Central Maintenance Computer System): Advanced built-in troubleshooting system used by Boeing.

• Airbus CFDS (Centralized Fault Display System): Advanced diagnostic system developed by Airbus. Both generally enhance ease of troubleshooting compared to previous systems.

BITE Philosophy

• BITE Monitoring: LRUs in the aircraft are constantly monitored by the BITE section in the computer system for safety reasons, to perform diagnostics and ensure proper functionality during operation

BITE Function

• Centralized Maintenance Device: BITE data is sent to a central maintenance device for easier fault identification and data analysis.

• Multiple Advantages of BITE Function: Includes single interface location, quick fault identification, simplified troubleshooting processes, standardization of equipment, and concise technical documentation.

• Power Up Tests: Safety tests to ensure system functionality upon power-up, focusing on crucial components.

• Cyclic Tests: System tests that are done without impacting normal operations. Examples include watchdog test for software failure and RAM checks.

• System Test: Troubleshooting tests for system integrity, following restoration or LRU replacement.

Specific Tests

• Stimuli-Based Tests: Tests designed to stimulate various components, such as actuators or valves, potentially impacting various aircraft systems.

Maintenance Control Display Unit (MCDU)

• System Components Enabled: The MCDU interacts with systems such as Flight Management (FM), Aircraft Condition Monitoring System (ACMS), Central Maintenance System (CMS), Satellite Communications System (SAT), and Air Traffic Service Unit (ATSU).

MCDU Utilisation

• Status Page: The MCDU displays a status page upon initialisation.

Simple BITE Circuits (Radio Altimeter)

• BITE Testing Procedure (steps): Procedures for testing radio altimeter BITE circuits involving LEDs, display confirmations, and test button activations.

• System Operation: Testing involves activating equipment, and checking the correct operation of the transceiver, antenna, and radio altimeter display.

Self-Test BITE (GPWS)

• GPWS System Activation: GPWS has a panel test button for initiating the system self-test.
• Test Sequence Stages: This sequence has predefined events such as lighting, indicators, specific warnings and aural cues, all based on prior activation input or criteria.

Aircraft Communications Addressing and Reporting System (ACARS)

• ACARS Functionality: A digital data link reducing flight crew workload, enabling the transmission of routine aircraft and system information.

• Ground Station Use: Ground stations receive information (including aircraft system faults) for quicker decision-making and parts preparation before aircraft landing.

• Accelerated Turnaround Time: Reduces time-consuming maintenance tasks and improves maintenance response time.

Data Bus Fundamentals

• Electronic Flight Instrumentation: Using digital microprocessors to replace mechanical instruments, with information linked via a multifunction display (MFD) or Digital Display Indicators (DDIs).

Airbus' Electronic Centralised Aircraft Monitoring System (ECAM)

• Display Systems: Displays aircraft information on two displays; primary and secondary.

• Display Locations (Older Models): The displays are close to traditional engine instruments in older aircraft models.

• CRT/LCD Options: In newer models, the display can be in a different location like the captain's or first officer's seat.

Electronic Flight Instrument System (EFIS)

• EFIS Role: Provides flight crew with the information for aircraft operation. Primarily showing analogue, discrete and digital components for flight control and data indication.

Primary Flight Display (PFD)

• Integrated Data: Combines EADI and EHSI data onto a single CRT display.

• Display Functions: Displays primary air data (attitude, altitude, airspeed), and navigation related information.

Multifunction or Navigation Display (MFD or ND)

• Combined Display Functions: Information including navigation, compass, radar, TCAS, flight management and diagnostics are integrated on single displays. The MFD is a backup for PFD and EICAS in case of failure.

Boeing's Engine Indicating and Crew Alerting System (EICAS)

• Digital Indication: Uses CRT or LCD for data representation eliminating the need for analogue instruments.
• Failure Display Indication: Indicators use colours and messages to alert crew about critical or warning failures.

Global Positioning System (GPS)

• Satellite-Based Navigation: Information from satellites for precise positioning needed for aircraft navigation, updates, and automatic flight control.

Airborne GPS Components

• There are various configurations of aircraft GPS systems involving panel-mounted receivers and controllers or remotely mounted receivers with data buses, coupled to either a computer or a Multi-function Control Display Unit (MCDU).

GPS BITE Test

• System Testing: The BITE (Built-In Test Equipment) test function for GPS receivers assesses the internal operation and link with the GPS antenna. There is a progress indication through LEDs.

Inertial Reference System (IRS)

• IRS Navigation Functions: The IRS independently senses angular rates for navigational calculations, independent of other system inputs.

• Data Generation: This system produces primary data including attitude and velocity.

IRS Components

• IRU (Inertial Reference Units): Maintains angular rates and accelerations, for aircraft position.
• MSU (Mode Selector Unit): Determines operations modes within the system.
• ISDU (Inertial System Display Units): Displays data to the flight crew (one per crew position).

IRS BITE

• Initial System Test (Verification): IRS performs a BITE test when initially powered on, that confirms the health of the system by monitoring internal circuitry and power supply.

Standby Power Supply (IRS)

• Uninterruptible Power (UPS): IRS power supply system automatically shifts between 28 VDC and 115 VAC, or from the main battery and backup batteries, in the event of a bus failure.

Traffic Alert and Collision Avoidance System (TCAS)

• Pilot Alert System: Provides distances and bearings of other aircraft within aircraft proximity, to the flight crew to aid in collision avoidance.

• Automatic Collision Alerts (Warning Levels): TCAS advises flight crew about potential collisions.

• TCAS Components: TCAS includes a computer, display screen, and directional antenna.

TCAS BITE

• Fault Detection: This process continually monitors TCAS for both system and interface faults.

FMS (Flight Management System)

• System Integration: An integrated system that collects data (flight plan), processes information and controls flight. Components include fuel quantity, control, inertial navigation, data link, and EICAS.

FMC (Flight Management Computer)

• System Redundancy: Most aircraft have one or more FMCs with data that is duplicated between them, guaranteeing redundancy in case one fails.
• Data Input and Distribution: Data inputs are received from different parts of the aircraft systems.
• External Control Display Unit (CDU): The CDU is the interface for entering and manipulating data in external control display units for the FMCs.

FMS BITE

• Automatic Testing: The system automatically runs a BITE test during system power-up, and manually if prompted. This test monitors for faults and provides critical data.