On-Board Maintenance Systems PDF

On-Board Maintenance Systems Introduction to Aeroplane On-Board Maintenance The On-board Maintenance System (OMS) has been developed to assist the maintenance personnel in fault-finding of complex avionics systems. It uses a range of techniques that are built into and integrated with aircraft system...

On-Board Maintenance Systems Introduction to Aeroplane On-Board Maintenance The On-board Maintenance System (OMS) has been developed to assist the maintenance personnel in fault-finding of complex avionics systems. It uses a range of techniques that are built into and integrated with aircraft systems. The OMS is a common framework for several functions needed to support the following activities: Aircraft maintenance (line and hangar, scheduled and unscheduled) Engineering follow-up (systems, aircraft and fleet monitoring) Aircraft reconfiguration. Consequently, it minimises ground time, increases the efficiency of maintenance processes, and improves the cost effectiveness. The On-board Maintenance System (OMS) consists of the systems below: Central Maintenance System (CMS) Data loading system Electronic library system Report printing system. On-board maintenance system 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 8 of 136 Aeroplane Central Maintenance System Aeroplane Central Maintenance Computers The CMS enables the mechanic to extract maintenance data concerning most of the aircraft systems and to initialise tests on these systems in modern aircraft. The main components in the CMS are the Central Maintenance Computers (CMC 1 and 2) and the Multipurpose Control and Display Units (MCDU 1, 2 and 3). Central maintenance system (CMS) The Central Maintenance Computer (CMC) acquires and processes (completes, correlates, memorises and presents) the data received from the BITE memories of system computers. The Multipurpose Control and Display Units (MCDUs) are used for control of the interrelated systems and the display of relevant output messages from them. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 9 of 136 Modes The Central Maintenance System operates in two modes: normal mode and menu mode. Normal Mode The Central Maintenance System (CMS) records fault messages generated by the Flight Warning Computers (FWC) and failure information produced by the BITE function integrated in computers. This mode is based on permanent real-time memorisation of fault data or operational BITE. Both system computers and also the CMCs memorise the fault data. Menu Mode The CMS allows the operator to obtain troubleshooting data from the systems and to initiate selftests via the MCDU (maintenance bite). This mode is available only on the ground. MCDU menu 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 10 of 136 Central Maintenance Computer Central Maintenance Computer (CMC) systems are used to provide a centralised location for aircraft fault information. This type of system is used in conjunction with the aircraft Electronic Centralised Aircraft Monitoring (ECAM) (Airbus) or Engine Indication and Crew Alerting System (EICAS) (Boeing) cockpit display systems. Central maintenance computer Only primary and independent warnings or maintenance status type warnings are transmitted to CMCs. The faults are acquired directly from the system BITEs and the CMC correlates the messages with aircraft parameters to amalgamate the fault with the time, date, flight phase, etc. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 11 of 136 CMC Data The CMC incorporates memory for the storage of maintenance data for retrieval. The CMC Central Processing Unit (CPU) organizes the received data into reports. One report available is the post or current flight report which presents all ECAM warning/caution and failure messages (class 1 or 2) recorded during the current flight. Data readout The data stored includes the following: The leg heading, date, flight number, city pair from, start time and A/C identification Warning messages transmitted ATA Sub ATA Calculated warning code Calculated warning type. The CMC compiles a Previous Flight Report (PFR) by storing all ECAM and failure messages recorded during the 63 previous flight legs. At each leg opening transition, the CMC 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 12 of 136 Files the current flight Updates the 64 last legs filed in the previous flight report Memorises the new leg heading: date, flight number, city pair from, start time and A/C identification. At each leg closing transition, the CMC memorises End time City pair to. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 13 of 136 CMC Switching Control and Self-Test Function Typically there are two CMCs available in large modern commercial aircraft for redundancy purposes. In normal operation, the CMC 1 is the master. It is connected at the output to all the systems. CMC can be switched through a BITE fault, MCDU selection or a pushbutton switch in a cockpit overhead panel. If the off legend illuminates on this pushbutton, the CMC 2 is active and considered the master. CMC bite failure will result in A failure indication on the MCDU and printer Failure details being sent to the main base via the Management Unit (MU) of the ACARS (optional system) or via the Air Traffic Service Unit (ATSU) (optional system). CMC 1 and CMC 2 are interfaced via an ARINC 429 link for the purpose of cross talk (X-TALK) which enables both CMCs to exchange general data in order to give the status of one computer with respect to the other (master or slave) and to select CMC 2 as the master in the event of a CMC 1 fault or manual switching. CMC Switching 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 14 of 136 Flight Warning Computers and ECAM Displays The flight warning computers monitor the operational data in order to display warnings and system information. The warnings will be displayed automatically with the relevant flight phase, and it displays until the end of the flight unless it has been cancelled. The CMC records failure information and messages received from the system BITE in a non-volatile memory system. These fault codes and messages can be recalled if necessary. ECAM display These system failures are classified in three categories, in function of their operational and safety consequences on the aircraft. Class 1 Failures which have an operational consequence for the current flight are categorised as Class 1 failures. They are displayed as a warning in real time on the ECAM and available on the MCDU. An example is the failure of one engine’s hydraulic pump. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 15 of 136 Class 2 Class 2 failures are failures which have no operational consequence for the current flight. The systems affected are identified on the ECAM STATUS page. An example is the loss of the continuity of one wing’s leak detection loop. Class 3 Class 3 failures have neither operational nor safety consequences for the aircraft. They are only available on the ground through the MCDU. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 16 of 136 Aeroplane System Computers The various aircraft systems are linked to the CMC with different hardware interfaces and different BITE characteristics. The system computers are categorised into three different types depending on their memory and connection to the central maintenance computers. Type 1 These are connected to both CMCs by an ARINC 429 output bus and to the CMC 1 by an ARINC 429 input bus. These systems can memorise failures occurring in the last 64 flights. This enables on-ground in-depth troubleshooting and an interactive test of the system and its components. Type 2 These systems memorise only failures from the last flight. A discrete input allows the system test to be initialised. The output connection is an ARINC 429 bus. Type 3 These systems cannot memorise failure messages. The discrete input permits the test to be initialised or reset. The discrete output indicates if the system is OK or not. System types 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 17 of 136 Aircraft systems (Types 1, 2 and 3) send their BITE information in parallel to both Central Maintenance Computers (CMCs), which both acquire and process information in the same manner. The CMC stores data concerning all the aircraft systems in non-volatile memories. Interfaces between the CMC and system computers 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 18 of 136 Multifunction Control Display Unit The Multifunction Control Display Unit (MCDU) consist of a screen for data display, an alphanumeric keyboard and line keys used to send commands to the connected systems. The MCDU provides access to data from the CMC system and allows testing of aircraft systems. Examples of this testing are self-tests which are used in conjunction with the AMM for LRU removal/installation checks and guided tests used for system fault-finding. The master CMC initialises the dialogue with the MCDUs. The MCDU interfaces and displays the CMS item in the main menu of the MCDU. Any operator wanting to use the CMC functions can access them through the CMS menu. Aviation Australia MCDU 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 19 of 136 Aircraft Communications Addressing and Reporting System The CMC can integrate with the Aircraft Communication Addressing and Reporting System (ACARS), Satellite Communication (SATCOM), wireless LAN and other communication systems. These communication systems will send maintenance information from the aircraft in advance of its arrival at the destination station. This allows maintenance personnel at the destination to begin the troubleshooting process and analysis before the aircraft even gets there. CMC-ACARS interface CMC-ACARS interface 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 20 of 136 Data Loading System on Aeroplanes Data Loading System As with all computer systems, a means to load and update software is a necessity. To facilitate this, a software loader or data loader is required. Typically, data loaders are linked with the Flight Management System (FMS) or are connected to a data bus coupler. Data loaders may be portable, taken to the aircraft and plugged in, or integrated into the avionics system. The data loader can be used to install and update software or download data recorded by on-board computers during aircraft operation. Data Loader Types Airborne Data Loaders Interconnection between the data loader and each computer is ensured by ARINC buses and discrete signals. The on-board data loaders are known as Multipurpose Disc Drive Units (MDDUs) on Airbus aircraft and Maintenance Access Terminals (MATs) on later-generation Boeing aircraft. Multipurpose disc drive unit (MDDU) 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 21 of 136 Maintenance access terminal Portable Data Loaders An interface cable connects to the back of the Portable Data Loaders (PDL) and supplies the airplane with ARINC data buses for loading via the Portable Maintenance Access Terminal (PMAT). It also supports a wireless link through which ground support personnel can interface directly with the server from outside the aircraft. PMAT 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 22 of 136 The PMAT/NT supports dual Operating System (OS) software, including both Aircraft OS and the Windows NT operating system. The aircraft operating system supports the on-board maintenance system, while the Windows NT operating system supports miscellaneous applications such as the aircraft maintenance manuals. The PMAT is also provided with LoadStar software, an application that controls the configuration of loadable software on each aircraft type and tail number in the airline’s fleet. Data Loading Loading information is similar to loading software onto your home computer. If there are several programmable computers incorporated into the avionics system, you may be required to select which computer is intended to receive the software. The Cursor Control Device (CCD) of the Maintenance Access Terminal (MAT) is the primary tool that the operator has to select and update the required system software in the Boeing 777 aircraft. CCD of maintenance access terminal In the Airbus system, the software is loaded via an MDDU. The data loader selector switch selects the computer by switching the required relays in the system. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 23 of 136 Data loader selector Correct software loads and software configurations are critical to aircraft operations. A software mismatch or a “glitch” as a result of incorrect loading procedures could conceivably cause a disastrous sequence of events, so it is imperative that maintenance manuals are strictly followed when loading software and that software and system functional and confidence checks are performed following software-loading. Software upload is a ground-only operation, whereas downloading can be accomplished in flight and on the ground. The downloads can be initialised by either the MDDU or MCDU. After the computer has acknowledged the request from the MCDU, it sorts the data to be transferred into files. The “TRANSFER IN PROG” message is displayed on the data loader LCD throughout the transfer. Some airborne data loaders at the completion of the update may require the disk to be removed; in other systems, the disk may be left and the system reads directly from it. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 24 of 136 Media Older data loaders normally use one of two media for the transfer of information into the aircraft: either a standard 3.5-inch disk (1.44 MB) or a CD-ROM (700+ MB). Newer media used may be Personal Computer Memory Card International Association (PCMCIA) cards or Universal Serial Bus (USB) sticks. Newer media types – PCMCIA card and USB stick Software Management Field Loadable Software (FLS) is loaded into the target hardware using a Portable Data Loader (PDL) or an Airborne Data Loader (ADL). After loading, the software should be verified on-board using the established processes and procedures detailed in the maintenance manual or associated approved maintenance or modification data. Loading FLS should be recorded in the Aircraft Configuration List (ACL), and a copy should be kept on-board the aircraft with a further copy also kept in the operator’s aircraft maintenance records system. After loading a Loadable Software Aircraft Part (LSAP), a Certificate of Release to Service must be issued by appropriately authorised line/base maintenance staff. It is essential that operators have appropriate procedures in place such that at any time it is possible to determine the equipment and software configuration of each aircraft in their fleet. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 25 of 136 Electronic Library Systems in Aeroplanes Electronic Library System Today, airlines receive their operational documentation in a variety of formats. Previously, airline personnel with a PC could run CDs from different sources, giving them all kinds of information needed for the job: system or spare part information, procedures, etc. The latest trend is to integrate all technical data for a given aircraft. This integrated approach will result in a Digital Electronic Library System (DELS). This electronic library system has replaced most of the normal cockpit paperwork with a computerbased reference system. This includes aircraft operations manuals, maintenance information, checklists, cabin management tools, systems logs, etc. It is typically interfaced into the existing flight management system. For instance, in the case of an engine emergency, the system could produce relevant checklists and the secondary ability to step down into relevant operations manual pages to review the relevant systems. Library display 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 26 of 136 An airliner usually comes with about 50 000 paper pages of integrated text and graphics in the form of operations, training, and maintenance data. The electronic library system is typically subdivided into the following: Operational requirements Maintenance applications Cabin management tools. Operational Requirements Taxi diagrams, ops manual, minimum equipment lists, pre-flight info, company policies and procedures, flight manuals, performance data, flight log books, check-lists, systems diagrams, approach plates and navigation charts are the documents used for operational requirements. Maintenance Applications Maintenance information includes a maintenance log, illustrated parts list, maintenance manuals, fault isolation and reporting data, troubleshooting procedures and equipment locations. Cabin Management Tools Cabin data includes checklists, special passenger needs, announcement scripts, cabin maintenance log books, flight schedules, reservations and supply inventory. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 27 of 136 Electronic Flight Bag This paperless cockpit concept is also known as the Electronic Flight Bag (EFB). These electronic devices are used on flight decks to allow flight crew members to perform a variety of tasks that previously required reference books, aeronautical charts and mathematical calculations. This information is usually shown on additional display units which are normally installed on side panels of the cockpit. Electronic flight bag The Civil Aviation Authorities define three EFB classes of hardware to be configured in this system. AC 120-76A and JAA Leaflet No. 36 contain similar descriptions of these classes. Class 1 Class 1 EFB systems usually are portable, Commercial Off-the-Shelf (COTS)–based computer systems used for aircraft operations. They are connected to aircraft power through a certified power source and are not attached to a mounting device on the flight deck. No administrative control process is required before they can be used in an aircraft. Class 1 EFBs are considered Portable Electronic Devices (PEDs). 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 28 of 136 Class 2 Class 2 EFB systems usually are also portable, COTS-based computer systems used for aircraft operations. They are connected to aircraft power through a certified power source and, unlike Class 1 EFB systems, are connected during normal operations to a mounting device on the flight deck, and airworthiness approval is required before the devices may be used in an aircraft. Connectivity to avionics equipment is possible. Class 2 EFBs are considered PEDs. Class 3 EFB Class 3 systems are installed systems (not PEDs) that require airworthiness approval. The certification requirements for Class 3 EFBs allow for applications and functions not performed using Class 1 and Class 2 EFBs. For example, Class 3 EFBs can accommodate moving-map software that also displays “own-ship” position—the position of the aircraft as it moves across the area depicted on the map. The EFB provides the flight crew with a paperless flight deck environment and enhances the quality of information available to the crew. In a Class 3 system, the captain’s EFB system is independent from the first officer’s EFB system. Each EFB system consists of a Display Unit (DU) and an Electronics Unit (EU). The flight crew interacts with the EFB via the DU by either pushing the buttons on the DU bezel or by using a touch-screen that is a feature of certain applications (e.g., electronic logbook). In addition, the flight crew can also make use of the Cursor Control Device (CCD) and the portable keyboard (optional). The EFB system can be interfaced with the aircraft printer and cabin surveillance cameras as optional features. 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 29 of 136 Display Unit The Display Unit (DU) operates as a computer monitor and input device. The flat panel is an ActiveMatrix Liquid Crystal Display (AMLCD) that shows graphics and video data in colour. The panel is also touch-sensitive. It measures where you press on the screen and changes that to digital data for the Electronics Unit (EU). Around the flat panel is a bezel frame with push-buttons, or keys. The keys across the top and bottom are permanent in function (for example, power). The Line Selection Keys (LSK) on the left and right sides operate in relation to the data shown on the touchscreen. The DU operates on 28-V DC power received from the EU. When the power-up sequence is completed, the DUs show the main menu page. The DU receives and shows graphics data from the EU. It can also display the image shown on the opposite-side DU via a fibre-optic cable. Display unit of EFB 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 30 of 136 Aeroplane Printing Aeroplane Printer The printer is designed to print reports which come from various systems, such as the following: Flight Management System (FMS) Central Maintenance System (CMS) Engine Monitoring System (EMS) Air Traffic Service Unit (ATSU) Aircraft Condition Monitoring System (ACMS). These printouts are available in flight or on the ground. The printer communicates with one system at a time. Aircraft cockpit printers are high-speed, single-copy printers designed to meet the requirements for flight deck mounting and power provision. The printers provide hard-copy output of pre-flight clearance delivery reports, weight and balance reports, ATIS reports, aircraft condition monitoring reports, power plant trend analysis reports, weather and radar reports, navigational aids, flight crew logs and IFE Cabin Management reports. Aircraft printer 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 31 of 136 Printing Process Data can be printed manually from the Multipurpose Control and Display Units (MCDUs) or automatically depending on the systems. Typical Printout 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 32 of 136 Aeroplane Condition Monitoring System Structural Monitoring Structural monitoring can be used for many reasons: To develop preventative maintenance policy by measuring the fatigue life of components in real time or in a testbed environment To identify flight phases where the greatest load is placed on the airframe, to thus avoid that flight phase wherever possible in normal operations To determine configurations which apply the greatest load factor on the airframe, e.g., replenished fuel tank configurations—full wing tanks may produce less strain on the wing attachment points than full fuselage tanks (when in flight). This data is obtained by sensors, strain gauges and piezo sensors. When installed on an aircraft, they are collectively called a data acquisition system. The instrumentation converts mechanical energy into electrical signals that are then processed into data to be stored or transmitted by radio signals to a control centre, where the information is monitored and analysed by engineers. Strain gauge 2022-12-13 B1-11k Turbine Aeroplane Aerodynamics, Structures and Systems CASA Part Part 66 - Training Materials Only Page 33 of 136