onboard maintenance systems

ONBOARD MAINTENANCE SYSTEM

Purposes

Provide maintenance personnel with an aid to fault diagnosis further to a complaint of the crew, thus saving time and money in the maintenance of the aircraft

Enabling technology; hosting a wide range of airline-specific software applications, including cabin information applications, graphical weather depiction, document viewing etc.

Multi Function Computer System (MCFC) – ATR72

Multi Function Computer System (MFC)

As fitted to the ATR72Two independent computers (MFC1 & MFC2)

Two independent modules (A & B) Receives signal from all the various systems and

system controls Self-test capability to ensure it is operation correctly

MFC Maintenance Panel

Bite Load IndicatorSystem Selector SwitchBite Advisory DisplayPTA/ERS PushbuttonTest PushbuttonData Bus Connector

MFC Control Panel

Located on the overhead panelAllows the switching on and fault monitoring

of the MFC system On : (Pushbutton pressed in) Module operates Off : (Pushbutton released) Module stops operating FAULT : Amber light comes on and the CCAS is

activated when a malfunction or electrical supply fault is detected.

3 Classes of Faults

Class 1 May have operational consequences on the current

flightClass 2

Do not have any operational consequences on the current flight or following flights

Class 3 No consequences on aircraft safety or availability Unlike Class 1 and Class 2 faults, these faults are not

indicated to the crew

Built-In Test Equipment (BITE)

A part of the computer dedicated for Permanent Monitoring

Internal monitoring Input / Output monitoring

Link Monitoring Between LRUs within the system


To meet requirements such as : high reliability Lower repair cycle times

To meet constraints such as : Limited technician accessibility Cost of testing during manufacture

To minimize the time on the ground needed for repair

To increase the level of safety of the system which contains BIST


Two types of test : Operational test

Input signals Protection Circuitry Control Circuitry Output Signals Operations BITE Circuitry

Maintenance test Carried out only when required and when the aircraft is

on the ground


Type1 ARINC 429 input and output bus, the input being

specific to the CFDS Capable of memorizing data concerning faults

detected on a maximum of 64 flights 34 basic and nine optional systems, total 75 units


Type2 A discrete and an ARINC429 data bus input from the

CMC Ten basic systems, total of 19 units

Type3 Characterized by discrete inputs and outputs Four basic and one optional system, total of 8 units


Central Maintenance Computer(CMC) All faults are recorded in the

non-volatile memory Detects faults in two ways :

Internally By monitoring its own operation

Externally By another aircraft system which received and

monitored information from the ‘faulty’ system

Multi-purpose Disk Drive Unit (MDDU) Two functions :

Uploading Data Downloading Data


Multi-function Control and Display Unit (MCDU) Provides an interface for ACARS Used almost all the times since it is the primary

means of operating the aircraft


Aircraft Communications Addressing and Reporting Systems (ACARS) A digital datalink system for transmission of short,

relatively simple messages between aircraft and ground stations via radio or satellite

MCDU menu differs in report for ON GROUND and IN FLIGHT


Panel for an aircraft model POSKY Boeing 737-800 with attached MCDU

Air Transport Association – ATA

Provide a common referencing standard for all commercial aircraft documentation

The standard numbering system is controlled and published by the Air Transport Association (ATA)


AIRCRAFT GENERAL

ATA Number Chapter Name

ATA 01 INTRODUCTION

ATA 05TIME

LIMITS/MAINTENANCE CHECKS

ATA 06 DIMENSIONS AND AREAS

ATA 07 LIFTING AND SHORING

ATA 08 LEVELING AND WEIGHING

ATA 09 TOWING AND TAXIING

ATA 10PARKING, MOORING,

STORAGE AND RETURN TO SERVICE

ATA 11 PLACARDS AND MARKINGS

ATA 12 SERVICING - ROUTINE MAINTENANCE

AIRCRAFT GENERAL


ATA Number ATA Chapter name

ATA 20 STANDARD PRACTICES – AIRFRAME

ATA 21 AIR CONDITIONING AND PRESSURIZATION

ATA 22 AUTOFLIGHT

ATA 23 COMMUNICATIONS

ATA 24 ELECTRICAL POWER

ATA 25 EQUIPMENT/FURNISHINGS

ATA 26 FIRE PROTECTION

ATA 27 FLIGHT CONTROLS

ATA 28 FUEL

ATA 29 HYDRAULIC POWER

ATA 30 ICE AND RAIN PROTECTION

ATA 31 INDICATING / RECORDING SYSTEM

AIRFRAMESYSTEMS



ATA 32 LANDING GEAR

ATA 33 LIGHTS

ATA 34 NAVIGATION

ATA 35 OXYGEN

ATA 36 PNEUMATIC

ATA 37 VACUUM

ATA 38 WATER/WASTE

ATA 45 DIAGNOSTIC AND MAINTENANCE SYSTEM

ATA 46 INFORMATION SYSTEMS

ATA 47 NITROGEN GENERATION SYSTEM

ATA 48 IN FLIGHT FUEL DISPENSING

ATA 49 AIRBORNE AUXILIARY POWER

ATA 50 CARGO AND ACCESSORY COMPARTMENTS

AIRFRAMESYSTEMS



ATA 51STANDARD PRACTICES

AND STRUCTURES - GENERAL

ATA 52 DOORS

ATA 53 FUSELAGE

ATA 54 NACELLES/PYLONS

ATA 55 STABILIZERS

ATA 56 WINDOWS

ATA 57 WINGS

STRUCTURE



ATA 61 PROPELLERS

ATA 71 POWER PLANT

ATA 72 ENGINE

ATA 73 ENGINE - FUEL AND CONTROL

ATA 74 IGNITION

ATA 75 BLEED AIR

ATA 76 ENGINE CONTROLS

ATA 77 ENGINE INDICATING

ATA 78 EXHAUST

ATA 79 OIL

ATA 80 STARTING

POWER-PLANT

Data Loading

Navigation information required by the aircraft systems is loaded using “Data Loaders”

Capable of downloading thousands of byte of information into the required system in a matter of seconds

Navigation Data Base (NDB)

Describes the environment in which the aircraft operates

Defined via the ARINC 424 standardNormally updated every 28 days, to ensure

that its content are current

Navigation Data Base (NDB)

Type of information Approaches

Standard Terminal Arrival Route (STAR) Instrument approach

Waypoints/Intersection Airports Runways Holding Patterns

Maneuver designed to delay an aircraft already in flight while keeping it within a specific airspace

Airways Highway in the sky

Structure Monitoring

Structural health monitoring is an important safety factor in aviation that might benefit from advanced smart systems for damage sensing and signal processing.

Structure Monitoring

Reasons : Prevent damage and possible hazard to the aircraft

following a catastrophic failure Detection of failures before any real damage has

occurred Safety issues To adapt operational usage to limit or even stop

damage growth

Low Cycle Fatigue

Low cycle fatigue is a term used to describe the thermal and/or mechanical loading conditions which cause premature failure of materials at less than 20,000 cycles

It is important to not have failures of this type for economical and safety reasons

Low Cycle Fatigue

Failure can occur in any area there is metal alloys but usually in the turbine or compressor sections

The choice of metal alloys and the design of engine components are the protection methods

Low Cycle Fatigue

Low Cycle Fatigue Counter (LCFC) receives inputs from the engine for such parameters as engine speed (NL and NH) of comppresors and turbines Processes the information to calculate engine damage

cycles Damage cycles are not related to actual damage, but

more a measure of the component life being consumed by there critical terms.

Health & Usage Monitoring (HUM)

Developed for fixed-wing aircraft, but focuses on rotorcraft, which benefit from a

system's ability to record engine and gearbox performance and provide rotor track and balance

May also monitor auxiliary power unit usage and exceedances, and include built-in test and flight data recording (FDR) functions


Expected to acquire, analyze, communicate and store data gathered from sensors and accelerometers that monitor the essential components for safe flight data allows operators to target pilot training and

establish a flight operations and quality assurance (FOQA) program, to determine trends in aircraft operations and component usage


Typical parameters monitored Engine Speed Engine Temperature Engine Pressure Engine Torque Accelerations Vibration Levels Aircraft Stress Built-In Test Exceedance / Event Monitoring Rotor Track and Balance (for rotorcrafts)

Central Maintenance System (CMS) – A330

Central Maintenance System (CMS)

To facilitate maintenance tasks by directly indication the fault messages in the cockpit and allowing some specific tests

Central Maintenance System (CMS)

To give maintenance technicians a central maintenance aid to intervene at system or subsystem level from multipurpose CDUs (Control Display Units) located in their cockpit

Two levels of maintenance : Out-station (line-stop) – LRU change At main base (hangar) – Trouble-shooting

Components

BITEs of all electronic systemsTwo fully redundant CMCs (Central Maintenance

Computers)Three MCDUs (Multipurpose Control Display

Units) Also used for :

FMGS (Flight Management and Guidance System) ACMS (Aircraft Conditioning Monitoring System) ATSU, which dialogue with the CMC for information display or

initiation tests

One printer A4 format

Normally only CMC1 is in used. Cmc2 is use when CMC1 fail.

Modes of Operation

Operates in two main modes : In flight, NORMAL or REPORTING mode

In NORMAL mode, the CMS records and permanently displays the failure messages transmitted by each system BITE

On ground, INTERACTIVE or MENU mode In INTERACTICE mode, the CMS allows the connection

of any BITE system with the MCDU, in order to initiate a TEST, or to display the maintenance data stored and formatted by the systems’ BITE

3 Classes of Failures

Class 1 Failures indicated to the flight crew by means of a

flight deck effectClass 2

Failures which can be left uncorrected until the next scheduled maintenance check

Maximum delay of 600 Flight HoursClass 3

Failures not indicated to the flight crew, with no fixed time quoted for correction

3 Classes of Failures

Class 3 report & print out

Minimum Equipment List (MEL)

Also known as Master Minimum Equipment List (MMEL)

A categorised list of systems, instruments and equipment on an aircraft which are not required to be operative for flight

Any equipment or system which is not included in the MEL must be operative for the aircraft to be allowed to fly

ARINC data buses

ARINC 429 Predominantly use in Airbus aircraft Based upon the integration of data based upon this

level data fusion One way communication data bus

One pair of data bus use for transmit data and another pair of data bus use for receive data

ARINC 629 Use in Boeing aircraft Bi-directional data bus for sending and receiving data

between multiple avionics LRUs

ARINC 429

Key display elements Display of aircraft system synoptic and status displays

available to the flight crew on the ECAM (Electronic Centralised Aircraft Monitor) displays

Use of the three CDUs as a man-machine interface for system test and diagnostic purposes

ECAM displays relating to the following provided by the Display Management Computers (DMCs) Engines Electrical system APU Hydraulic system Landing gear

Central Maintenance Computing System (CMCS) – Boeing 777

Central Maintenance Computing System (CMCS)

Supports both line and extended maintenance functions through menu selections on the MAT and PMAT

Used for : Monitoring the aeroplane’s systems for faults Processing fault information Supplying maintenance information Monitoring Flight Deck Effects (FDE)

Receives maintenance messages from ACMS (Aeroplane Condition Monitoring System (ACMS), if a fault is detected

Maintenance Access Terminal (MAT)

Display Screen and Controls Selecting and viewing fault data

Keyboard Stored when not in use Allows certain entries and controls displayed data

Cursor Control Device Receives power supply of 115V AC via the “MAINT

ACCESS TERMINAL” circuit breaker Contains :

Track Ball Selection Keys Brightness Control

Portable Maintenance Access Terminal (PMAT)

Similar functions to MATFive PMAT receptacles, located throughout

the aircraft : MAT Position Electronics Bay Nose Gear Right Main Gear Bay Stabilizer Bay

Flight Deck Effect (FDE)

The airplane systems monitor conditions related to loss of a system or function. If a condition exists that requires repair or deferral, the airplane system sends FDE data to the AIMS primary display system (PDS). The PDS shows the FDE.

Inform the flight and ground crew of the conditions relating to the safe operation of the aircraft

FDE data is used along with the aircraft’s maintenance to isolate the fault

Airplane Condition Monitoring System (ACMS)

Provides a record of selected airplane systems performance and flight conditions for maintenance and Flight Data Monitoring purposes

The system consists of : a Digital Flight Data Acquisition Unit a Digital Flight Data Recorder (DFDR) a Quick Access Recorder an accelerometer a Data Management and Entry Panel

Airplane Condition Monitoring System (ACMS)

Accessed through fromats on the MAT, PMAT or the side displays on the flight deck

Used to produce reports of : Analyse airplane performance Analyse trends Report significant events Troubleshot faults

Receives data from the Airplane Conditioning Monitoring Function (ACMF)

Airplane Conditioning Monitoring Function (ACMF)

Combination of standard and custom software

method of determining aircraft health through reporting on aircraft systems such as powerplants and structures

Sends data to : Quick Access Recorder (QAR) Maintenance Access Terminal (MAT) Portable Maintenance Access Terminal (PMAT) MAT or PMAT disk drives Flight deck Side Displays (SD) Data Communication Management Function (DCMF)

Quick Access Recorder (QAR)

Records data sent from the ACMF onto a 3.5ich, 128MB optical disk, holding 41 hours of data

An airborne flight data recorder designed to provide quick and easy access to raw flight data

QAR is not required on commercial flights and is not designed to survive an accident

Quick Access Recorder (QAR)

Contains two memories : Flash Memory (non-volatile)

Holds configuration data, system data and identification files

Send this data to the formatter Formatter Memory

Arranges the received data, sends it to the cartridge drive circuits

Cartridge Drive Circuits Sends data to the 16bit LCD displays :

Stored Data QAR Menus Test Results Messages

Airplane Information Management System (AIMS)

Collects and calculates large quantities of data and manages this data for several integrated aircraft systems

Used to assemble the necessary data for the CMCS function

Two AIMS boxes handle the six primary flight and navigation display Four Input/Output Modules (IOM) Four Core Processor Modules (CPM)

Airplane Information Management System (AIMS)

IOM Transfer data between the software functions in the

AIMS CPMs and external sourcesCPM – 4 types

CPM/COMM – Communications CPM/ACMF – Aircraft Condition Monitoring Function CPM/B – Basic CPM/GG – Graphics Generator

Flight Compartment Printing System

Supplies high-speed hard copies of text for the following systems : Primary Display System (PDS) Airplane Condition Monitoring System (ACMS) Central Maintenance Computing System (CMCS)

Receives data from the print driver partition of the Data Communication Management Function (DCMF)

Flight Compartment Printing System

DCMF prioritises data sent to the printer in the following order : Flight Deck Communication Function (FCDF) of the

DCMS Central Maintenance Computing Function (CMCF) of

the CMCF Airplane Condition Monitoring Function (ACMF) of

the ACMS Multi Function Display (MFD)

onboard maintenance systems

Documents