Enabling avionics life-cycle savings through ARINC standards for integrated vehicle health management applications

By Michael D. Sudolsky, associate technical fellow at BoeingThe use of commercial-off-the-shelf (COTS) technology brings many performance advantages to designers of commercial and military avionics and electronics systems but not without one big headache -- obsolescence. It affects all levels of design -- as parts become obsolete designers struggle to manage the life cycle costs associated with COTS products that have a two-year shelf life in systems lasting decades.Managing life cycle costs is an important issue within data formatting standards on commercial aircraft, and recorder utilization of these standards enables abundant life-cycle savings in these applications. ARINC standards 573/717, 767, and 647A, in large part, have been developed to facilitate Flight Data Recorder (FDR) mandatory data capture requirements. These standards also foster important equipment interchangeability or interoperability requirements. Since they are applicable to Aircraft Condition Monitoring System/Function (ACMS/F) recording, critical Integrated Vehicle Health Management (IVHM) applications are supported.This article is based on a paper by the author titled "ARINC 573/717, 767 and 647A: The Logical Choice for Maintenance Recording and IVHM Interface Control or Frame Updates." It can be found online at http://www.phmsociety.org/node/46.IVHM and ARINC standardsImportant IVHM operations require the ability to continually improve or update recording, and Flight Recorder Electronic Documentation (FRED, or ARINC 647A) use as an IVHM Interface can indeed foster continual ACMS improvement/maturation. Additionally, the extension of these standards to any avionics controller or system interface lends itself to improved troubleshooting methods. This enhanced use of ARINC standards is a crucial element of Health Ready Subsystem implementation, prototyped in the Boeing Research and Technology's IVHM Operational Environment.ARINC standards specify the air transport avionics equipment and systems used by more than 10,000 commercial aircraft worldwide. They aid development of equipment designs so standardization of physical and electrical characteristics can result without detriment to engineering initiative. Very common ARINC standards cover important specifications for electronic unit sizes, connectors, and wiring.Subframe based recording has been used for more than 40 years, and many associated COTS data processing and reporting tools exist that can expedite IVHM deployment and mitigate risks.ACMS/F life-cycle advantagesMany program phases are improved with ACMS/F maturation or IVHM interface utilization throughout the life-cycle of a weapon system or commercial vehicle. This cannot be underestimated as IVHM involves cost avoidance that is frequently difficult to fund, and addressing as many program efforts as possible aids health management implementations. Early in the program, when concept of operations and affordability based design trade-offs are made, considerations reflecting ACMS/F IVHM interface technique utilization are important. For example, if initial lab development and integration testing utilized unique recording frames for verification/quality assurance purposes, then outstanding leverage of standard hardware results (e.g., unique "lab test only" parameters are now available for operational use later in the program). This also applies to production testing. An ACMS/F map can be used for on-board production test verification -- especially important when considering that results can be reported on-board using airplane displays.An integrated diagnostic model is one critical item that is utilized for system development, and includes important testability design influence. IVHM Interface and Boeing On-Line Diagnostic Reporting (BOLDR) techniques allow for capturing necessary failure data to both aid in line replaceable unit (LRU) troubleshooting/repairs, and continual model improvement, enabling full association from any changes into the diagnostic/prognostic construct of the integrated system.Flight testing can also be enhanced using ACMS/F for reporting test point completions and storing Flight Operational Quality Assurance (FOQA) event results. FAA certification requires thorough verification/validation testing, and use of the same ACMS/F hardware for event recording aids validation and follow-on FOQA by using standard tools and setting exceedance levels, respectively.Additionally, class II changes are regularly performed to mitigate LRU part obsolescence (e.g., a given Integrated Circuit is not manufactured anymore and a form/fit/function equivalent part is utilized).While the supplier performs testing to ensure equivalence, unexpected problems still transpire (e.g., a timing issue associated with certain system operational modes), and updated diagnostic models and IVHM interface use can significantly aid new part maturation -- using associated operational data for the new part to quantify equivalence, or mitigate risk if otherwise.These examples aid nearly all of the product cycles, and since the same standard equipment can now be used without requiring special equipment, tools, or associated skills full-scale IVHM implementation should be assured. One significant item supports active IVHM Interface utilization -- ACMS/F maintenance data does not affect in-flight airplane performance, thus flight-test and other associated quality control functions are not required -- thus avoiding costly operational software changes. Thus, these FRED and BOLDR IVHM interfaces support a continual improvement method that can be used to rapidly address high cannot-duplicate, no-fault-found, removal or test-time rates.COTS tool availabilityA critical feature of recording using an ARINC standard is ample COTS tool availability. Additionally, 40 years of ARINC 573/717 subframe use has led to many feature improvements along with very mature and reliable tools. Many subframe data processing and reporting tools exist, and each has inherent advantages.Some providers have had success in supporting regulatory agency analysis requirements, and graphing needs. COTS relational database tools have also shown reporting speed and ad hoc analysis advantages, especially within the technical community of specific programs. Boeing is also performing research wherein the same database is used for any aircraft data, including subframe recordings, and other related uses.SummaryARINC 573/717, 767 and 647A have greatly aided FDR development and deployment, including important unit interchangeability requirements/supplier product availability. Since these ARINC standards are applicable to ACMS Recording, several important IVHM operational aspects are supported, including ample data processing and reporting tool availability, the ability to rapidly update what is recorded using FRED tools, and, numerous techniques to optimize what is collected including BOLDR IVHM system interfaces. Additionally, the continued demonstration of these techniques in the Boeing IVHM Operational Environment is aiding business unit deployments, to the delight of our commercial and military customers.About the author

Mike Sudolsky, associate technical fellow, is the first Boeing member inducted for ACMS/F expertise. His 27 years in the industry cover disciplines such as aerospace testing (test program sets and flight testing) and System Design (ACMS/F and other subsystems) that have enabled his current IVHM work. This work includes his Fault Recording and Reporting Method invention (US Patent #6,115,656) that forms the basis of BOLDR. (Note: BOLDR is a registered trademark of Boeing.)