727 to 787: Evolution of Aircraft Maintenance Systems
<div>727 to 787:</div><div>Evolution of Aircraft Maintenance Systems</div><div>**** Hidden Message *****<br></div> <div>727 to 787:</div><div>Evolution of Aircraft Maintenance Systems</div><div>SPECIAL REPORT</div><div>Aircraft maintenance has come</div><div>a long way, from push-button,</div><div>light-up tests for determining the</div><div>health of individual, federated</div><div>avionics boxes to centralized</div><div>airplane management systems</div><div>t h a t i n t e r a c t i ve l y c o l l e c t</div><div>data from all systems. It has</div><div>evolved to become a valuable</div><div>t r o u b l e s h o o t i n g t o o l f o r</div><div>maintenance technicians.</div><div>Testing mechanical and analog systems in vintage aircraft—such as the Boeing 727</div><div>and 737 Classic, and the McDonnell Douglas DC-9 and MD-80—consisted of little more</div><div>than pushing a button to supply current to the internal circuitry. A green light would</div><div>illuminate to say everything was OK. Such “push-to-test” and “go/no go” systems were</div><div>the beginnings of built-in test equipment (BITE) for avionics technicians.</div><div>The central maintenance computer on Honeywell’s Primus Epic® system</div><div>Star ting in the early 1980s,</div><div>digital systems that use electronic</div><div>hardware and software</div><div>to carry out functions previously</div><div>performed by mechanical and analog</div><div>systems were introduced on Boeing’s 737</div><div>Next Generation, 757 and 767 aircraft,</div><div>as well as the McDonnell Douglas MD-</div><div>90 and Airbus A320. These new digital</div><div>systems brought their own challenges</div><div>to aircraft maintainers, as the ability to</div><div>troubleshoot these black boxes by detecting</div><div>and isolating faults was limited to the</div><div>indications provided by the system.</div><div>From this challenge came the first</div><div>standard for health management: ARINC</div><div>604, “Guidance for Design and Use of</div><div>Built-In Test Equipment.” Developed by</div><div>ARINC and industry partners, this standard</div><div>represents the birth of vehicle health</div><div>management, where one or more line</div><div>replaceable units (LRUs) equipped with</div><div>dedicated front panels gave maintenance</div><div>technicians the ability to test and query</div><div>the system. Such panels included pushbuttons</div><div>and rudimentary display capabilities</div><div>that showed alphanumeric readouts.</div><div>By the mid-1980s, with the introduction</div><div>of the first glass cockpits on airplanes</div><div>such as the McDonnell Douglas</div><div>MD-11, mechanics were able to test and</div><div>query several systems through centralized</div><div>display panels shared by a number</div><div>of LRUs. However, these common display</div><div>panels report the results of each</div><div>LRU independently and do not have the</div><div>capability to consolidate related fault</div><div>indications from multiple LRUs. While</div><div>this is a significant improvement, maintenance</div><div>technicians must still manually</div><div>consolidate these results; otherwise they</div><div>would remove and replace LRUs that</div><div>merely report symptoms rather than</div><div>replacing the actual faulty LRU.</div><div>In the late 1980s, the 747-400 was</div><div>introduced. It contains two Central Maintenance</div><div>Computers (CMCs) that receive</div><div>fault status indications from most airplane</div><div>systems, consolidate these results</div><div>to determine the source fault, and correlate</div><div>the source fault indication to the</div><div>flight deck effects (e.g., flight crew alerts)</div><div>caused by the fault. The CMC can display</div><div>these results on the Multifunction</div><div>Control Display Unit (MCDU) or downlink</div><div>these results while in flight to ground stations</div><div>to support maintenance planning.</div><div>The CMC also provides an integrated</div><div>user interface to perform ground tests</div><div>on all connected member systems. However,</div><div>the 747-400 CMC accomplishes</div><div>the fault consolidation via a complex</div><div>set of logic equation-based diagnostics.</div><div>Development and maintenance of this</div><div>“brute force” approach was a great technical</div><div>challenge, due to the many interrelationships</div><div>between the equations.</div><div>This approach requires detailed understanding</div><div>of all the equations in order to</div><div>ensure that they are consistent and correctly</div><div>represent system behavior.</div><div>These issues are compounded when</div><div>the aircraft is upgraded with new systems.</div><div>It took a long time to work out</div><div>all the health management system’s</div><div>idiosyncrasies, causing an early lack</div><div>of confidence in the system by airline</div><div>mechanics—“Give me wrong answers</div><div>once, and my confidence goes down 50</div><div>percent! Give it to me twice, and I stop</div><div>using it!” In time, the 747-400 logic has</div><div>matured and become a valuable tool for</div><div>maintenance technicians.</div><div>Following the development of, and</div><div>using lessons learned from the 747-400,</div><div>Boeing, Honeywell and others in the</div><div>airline, aircraft and avionics industries</div><div>developed updated standards for maintenance</div><div>systems, including ARINC 624,</div><div>“Design Guidance for Onboard Maintenance</div><div>System.”</div><div>Central Maintenance & Airplane</div><div>Condition Monitoring</div><div>Health management processes include</div><div>the following:</div><div>➤ Fault detection and isolation philosophy,</div><div>➤Optimal sensor quantity and placement</div><div>guidelines,</div><div>➤Standard built-in-test designs and</div><div>practices,</div><div>➤Metrics, e.g., fault coverage percentage</div><div>or fault isolation accuracy percentage,</div><div>➤Verification and validation plans and</div><div>procedures,</div><div>➤ Fault modeling guidelines, and</div><div>➤Interface standards between subsystems</div><div>and central maintenance systems.</div><div>Coordination and integration of those</div><div>processes are key to effective vehicle</div><div>health management. The ultimate goal</div><div>was to improve testability, isolate failures,</div><div>improve system safety and reliability,</div><div>and reduce life-cycle costs.</div><div>Many of today’s aircraft employ some</div><div>type of central maintenance system</div><div>that fulfills the role of collecting faults</div><div>from all subsystems, performing some</div><div>root cause determination and recommending</div><div>repair actions. In the Boeing</div><div>777, those functions are performed by</div><div>the Honeywell-developed central maintenance</div><div>system software. It consists of</div><div>two portions: the Central Maintenance</div><div>Computing Function (CMCF), which</div><div>detects faults after they happen, and the</div><div>Airplane Condition Monitoring Function</div><div>(ACMF), which collects data to enable</div><div>prediction of problems in advance.</div><div>ACMF capabilities existed previously in</div><div>earlier federated systems, but the B777</div><div>The development of health management systems</div><div>reflects the evolution of avionics architectures.</div><div>From the B727 to the B777, health</div><div>systems have supported mechanical/analog,</div><div>digital, federated and modular avionics.</div><div>Vehicle Health Management</div><div>Evolution for Commercial Aircraft</div><div>was the first aircraft to implement them</div><div>in the same cabinet with an integrated</div><div>advanced user interface, according to</div><div>Gautham Ramohalli, the engineering</div><div>manager of Honeywell Aerospace’s</div><div>Aircraft Diagnostics and Monitoring</div><div>Systems. This integration provided the</div><div>ACMF with unprecedented access to</div><div>aircraft signals and enabled a common,</div><div>point-and-click interface on the aircraft</div><div>for both CMCF and ACMF.</div><div>As opposed to the logic equationbased</div><div>diagnostics on the 747-400, the</div><div>777 CMCF employs a Honeywell-patented,</div><div>model-based diagnostics technology</div><div>to drive fault processing and ground</div><div>tests, and display textual information to</div><div>the maintenance technician. The fault</div><div>model encodes the observable symptoms</div><div>for each fault condition, based on</div><div>the modeled effects of each fault condition</div><div>within the member system and the</div><div>connectivity of LRUs within the aircraft.</div><div>Each system on the air plane is</div><div>responsible for fault detection and reporting</div><div>in accordance with a set of Boeingdefined</div><div>member system requirements.</div><div>The reporting system communicates</div><div>with the CMCF, using an aircraft-wide</div><div>standard protocol that provides for fault</div><div>reporting, configuration reporting and</div><div>commanded ground tests.</div><div>Model information is contained in a</div><div>separately loadable database referred to</div><div>as loadable diagnostic information (LDI).</div><div>The LDI is created by Boeing, using the</div><div>Honeywell-developed ground-based Diagnostic</div><div>Model Development Tool (DMDT),</div><div>the purpose of which is to collect and validate</div><div>the fault model for the aircraft.</div><div>DMDT is seeded by imports from</div><div>various sources. These include the airplane</div><div>interface control database, crew</div><div>alerting message database, and failure</div><div>modes and effects analyses. Aircraft</div><div>system designers enter subsystemspecific</div><div>diagnostic information and links</div><div>to complete the basic model. Boeing,</div><div>as the aircraft system integrator for the</div><div>777 and 787, completes the aircraft-level</div><div>model by performing tasks, including</div><div>analysis and correction of DMDT proposed</div><div>propagation relationships and</div><div>definition of fault isolation relationships</div><div>for faults reported by multiple systems.</div><div>This aircraft-level modeling determines</div><div>fault consolidation and fault cascade</div><div>effect removal, and ensures correct flight</div><div>deck effect correlation.</div><div>The aircraft condition monitoring</div><div>function provides a programmable method</div><div>for triggering custom data reports.</div><div>Report triggers can be defined, using</div><div>interface control document signals combined</div><div>with logic units, to collect sample</div><div>data at a predefined rate and time before</div><div>and after the trigger event.</div><div>Resulting reports can be stored on</div><div>onboard mass storage devices (e.g., the</div><div>Maintenance Access Terminal hard drive</div><div>on the 777, and the crew information system</div><div> servers on the 787), downlinked</div><div>via the airborne communications addressing</div><div>and reporting system (ACARS) or, on</div><div>the 787, one of the available broadband</div><div>communication paths, such as Gatelink (a</div><div>wireless local area network technology),</div><div>Connexion by Boeing, or Inmarsat’s</div><div>Swift64 satellite service.</div><div>Such a capability is key to improving</div><div>on-time departures because it gives line</div><div>maintenance staff time to prepare even</div><div>while the airplane is still in the air. “What</div><div>that does is extend the maintenance</div><div>technician’s ramp time from 30 minutes</div><div>to four hours by giving him 3.5 hours</div><div>advance notice,” says Don Morrow, Honeywell’s</div><div>director, New Boeing Platforms.</div><div>The user interface employed by the</div><div>CMCF enforces a common look and feel</div><div>for all member systems. This reduces the</div><div>amount of training required for maintenance</div><div>personnel, regardless of the system</div><div>they are working on, e.g., landing gear,</div><div>environmental control system or avionics.</div><div>Differences from Previous Systems</div><div>Most previous maintenance systems</div><div>depended on the individual member</div><div>systems to store the fault data in their</div><div>LRU/LRM (line replaceable module). To</div><div>display a system’s stored data, a bidirectional</div><div>command-request protocol is</div><div>performed to retrieve the data each time</div><div>a user request is made.</div><div>The CMCF uses local fault storage to</div><div>store the data, which simplifies the faultreporting</div><div>interface for the participating</div><div>systems. The CMCF retrieval of fault data</div><div>is all contained within the CMCF itself. This</div><div>speeds up data retrieval while requiring no</div><div>handshaking or protocol with member</div><div>systems during the display process.</div><div>The CMCF was built upon previous</div><div>Honeywell maintenance systems that</div><div>added maintenance message text to maintenance</div><div>message codes. The objective is</div><div>to present maintenance message information</div><div>in clear English text that is usable by</div><div>the maintenance technician, rather than</div><div>having a code that requires translation.</div><div>Embraer’s OMS</div><div>The Honeywell Primus Epic® onboard</div><div>maintenance system, which consists of</div><div>a CMC and the airplane condition monitoring</div><div>system, is finding its first 70- to</div><div>110-passenger aircraft application in the</div><div>EMBRAER 170/190 family of commercial</div><div>jetliners.</div><div>Many of the system health management</div><div>capabilities of the Embraer aircraft are</div><div>similar to those of the 777 onboard maintenance</div><div>system. These include the following:</div><div>➤Real-time fault monitoring,</div><div>➤Integration with the data loading</div><div>system,</div><div>➤Point-and-click intuitive navigation,</div><div>➤Comprehensive system coverage—</div><div>weather radar to auxiliary power unit,</div><div>➤Open architecture,</div><div>➤Loadable diagnostic infor mation</div><div>database,</div><div>➤Capability to display bus parameters</div><div>and member status, and</div><div>➤Remote terminal connectivity.</div><div>“These go beyond having a system</div><div>that just reports faults to one that quickly</div><div>gives maintenance technicians a snapshot</div><div>of all the member systems on the</div><div>aircraft,” says Eric Heinzer, Honeywell’s</div><div>A maintenance technician accesses data</div><div>using a wireless terminal</div><div>Customer and Product Support leader</div><div>for regional OEMs. “A mechanic having</div><div>to deal with a series of faults now can</div><div>easily determine what systems are not</div><div>on-line and start there.”</div><div>Like the system now being developed</div><div>for the Boeing 787, the EMBRAER</div><div>170/190 Primus Epic system has a</div><div>separately loadable database, so that</div><div>loadable diagnostic information can be</div><div>updated without having to alter the CMC</div><div>functional code. In addition, the CMC is</div><div>navigable, with a cursor control device</div><div>comparable to that on the 777. Another</div><div>common feature with the Boeing widebody</div><div>is the ability to query the CMC on</div><div>the EMBRAER 170/190 with a commercial</div><div>off-the-shelf laptop.</div><div>On the EMBRAER 170/190, the CMC</div><div>is part of Honeywell Aerospace’s Primus</div><div>Epic integrated avionics system. The</div><div>CMC resides on a dedicated module</div><div>within the Primus Epic modular avionics</div><div>unit (MAU) and utilizes a commercial offthe-</div><div>shelf (COTS) operating system. The</div><div>CMC software stores maintenance data</div><div>locally on the CMC module in a format</div><div>that is later downloaded and analyzed</div><div>with common PC software applications.</div><div>Honeywell evaluated the need to</div><div>bridge airborne embedded software with</div><div>PC software and made a design decision</div><div>to use the PC software on the CMC line</div><div>replaceable module in the Primus Epic</div><div>MAU cabinet, according to Gary Bird,</div><div>Honeywell’s product portfolio leader,</div><div>Telematics and Diagnostics. This decision</div><div>meant that PCs could be connected</div><div>directly to the CMC module, using COTS</div><div>hardware and protocols.</div><div>In turn, this provided the ability to create</div><div>a CMC interface console, using a PC</div><div>instead of specialized hardware. The CMC</div><div>is specifically designed so that its operational</div><div>interface in the cockpit requires no</div><div>keyboard. The interface is point-and-click</div><div>and works with a variety of cockpit-mounted</div><div>cursor control devices.</div><div>777 to 787</div><div>Boeing’s 787, now under development,</div><div>will also utilize the Honeywell-patented,</div><div>model-based CMCF and ACMF technology,</div><div>and in this application, the health</div><div>management function is part of the crew</div><div>information system/maintenance system</div><div>(CIS-MS). The CIS-MS provides a</div><div>networking infrastructure that enables</div><div>airborne functions to interact with ground</div><div>components and a computing environment</div><div>capable of hosting RTCA/DO-178B,</div><div>Level D and Level E, software applications.</div><div>Hosted by the CIS are various standard</div><div>applications, including the maintenance</div><div>system, electronic flight bag (EFB), data</div><div>loader, flight deck printer and terminal</div><div>wireless LAN unit (TWLU).</div><div>The preceding systems provide interfaces</div><div>to airplane communication systems,</div><div>airline applications and information systems</div><div>in an open architecture that can be extended</div><div>and adapted. Maintenance system control</div><div>and display are available through several</div><div>user interfaces. Web-based technology is</div><div>used for the primary interface, and ARINC</div><div>661 is provided as a backup.</div><div>The primary interface to the maintenance</div><div>system is a commercial off-theshelf</div><div>PC that uses a typical Web browser</div><div>interface. Unlike the Boeing 777, these</div><div>devices are not certified or installed</div><div>in the airplane, and an operator may</div><div>choose to stow a laptop computer on</div><div>the airplane for convenience. If a laptop</div><div>computer is not available, the cockpit</div><div>multifunction display is equipped to</div><div>provide the minimum CMCF display</div><div>functionality necessary to prepare the</div><div>airplane for dispatch.</div><div>Basic to the 787 airplane is the terminal</div><div>wireless LAN unit, which provides</div><div>the airplane side of the Gatelink connectivity</div><div>and lets maintenance technicians</div><div>electronically access the airplane when</div><div>it is located at the gate. An optional crew</div><div>wireless LAN unit (CWLU) provides the</div><div>ability to use a wireless laptop computer in</div><div>the proximity of the airplane to perform all</div><div>of the available maintenance system control</div><div>and display functionality. The CWLU</div><div>system provides necessary security and</div><div>allows for multiple simultaneous users.</div><div>Easy Access</div><div>With this wireless capability, maintenance</div><div>technicians will not have to fight</div><div>their way through departing passengers</div><div>to get into the cockpit or even have to</div><div>hook up their computers to external connections</div><div>on the tail or engines to access</div><div>troubleshooting data. They can access</div><div>data while roaming freely around the</div><div>exterior of the airplane. Up to four remote</div><div>terminals can be connected to the CMC</div><div>at one time, allowing for a faster aircraft</div><div>build in the Boeing factory, as well as</div><div>expedited return to service in airline</div><div>maintenance operations.</div><div>In addition, the maintenance system</div><div>will provide links to the electronic airplane</div><div>maintenance manuals (AMMs), allowing</div><div>access to detailed maintenance and troubleshooting</div><div>procedures without leaving</div><div>the airplane. “By auto-linking to electronic</div><div>documents on the 787—something that</div><div>was not available on the 777—we’re creating</div><div>an essentially paperless and medialess</div><div>airplane,” explains Bird.</div><div>How soon can 787 operators see</div><div>the benefits of Honeywell’s crew information</div><div>system/maintenance system?</div><div>The new Boeing aircraft’s first flight is</div><div>scheduled for August 2007, with certification</div><div>in March 2008 and first deliveries</div><div>by May 2008. There were, through</div><div>January 2006, 291 orders for the twinaisle</div><div>Boeing 787.</div><div>B777 OMS menus, including higher-level page</div><div>and (right) flight deck effects correlation page.</div> 727 to 787: Evolution of Aircraft Maintenance Systems 值得下载收藏，谢谢 感谢楼主分享 维修培训的材料哦 不错。好好学习一下。 谢谢分享了 111111111111111111111111111111111 好东西，谢谢楼主
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