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Case Study

EASi Validates Complex Avionics Controller System

Faced with a lack of domain expertise and internal resources, an aviation technology provider asked EASi to review designs, analyze failure cases and recommend design solutions for its avionics controller.

Reliability plays a major factor in the competitive world of advancing technology and is the highest-priority requirement in the aerospace industry. Companies that develop avionics systems use a plethora of techniques to make sure their products are reliable even at altitudes of 50,000 feet. Typically, product reliability measures are defined and addressed from the beginning of and throughout the design lifecycle. These measures include reliability prediction techniques that involve mathematical calculations and methodologies for analyzing the life and quality of products.

The client and challenge
The client is a high-end technology provider that develops aircraft engine systems and controllers. It is the world leader in the aircraft industry and has brought the latest technologies to its avionics systems.

The client was developing a new aircraft controller system that was complex and had many electromechanical and software components, external sensor inputs, controls and coils. During the initial phase of development, the client needed to verify the reliability and robustness of the initial design. Due to a lack of domain expertise and internal resources, the client sought out an engineering consultant to review designs, analyze failure cases and recommend design solutions.

The review scope included:

  • Electrical, mechanical and software design
  • Reliability analysis
  • Fault tree analysis
  • Review of findings
  • Design updates

The EASi solution
EASi provided a reliability analysis solution based on military and aerospace safety standards. A multi-stage product analysis approach was applied, which involved:

  • Phase 1:  Reliability analysis based on MIL-HDBK-217, ARP4761 and ISO 26262

    A reliability analysis of the existing system was conducted using industry standards. EASi used the part stress method to conduct detailed, component-level reliability analysis during worst-case environmental conditions. The complete system was broken down into individual components, and the failure rate of each component was calculated. EASi contacted multiple manufacturers to verify that their components were reliable for use in an avionics system. EASi leveraged ISO Graph Reliability Work Bench to calculate block failures, mean time between failures (MTBF), mean time to failure (MTTF) and the system failure rate. The failure rate of a component was determined through voltage power stress analysis, simulation of the circuits, temperature analysis and a review of failure reports from the component manufacturers. An adjustment factor was also applied. Per product requirements, once manufactured, temperature would be the only factor the varies frequently. As such, the final report detailed the failure-in-time (FIT) data and MTBF data with complete system reliability details and the failure versus temperature performance charts.
  • Phase 2:  Design review — schematic and PCB analysis, software code coverage

    EASi performed a complete electrical and software design review. During this review, we used simulation to trace any design issues and performed a detailed review of the system and circuits. This included identifying all schematic errors, design issues, PCB errors, footprint errors, layout errors and gaps in protection. Our team then moved to fine-tune the design, which included using industry best practices to propose schematic changes, design changes, code corrections and PCB updates. EASi validated the software using IDE tools, downloading the software onto actual hardware and using simulation and static analysis.
  • Phase 3: Fault tree analysis considering the entire system, including electrical, mechanical and software

    EASi completed a deep-level fault tree/failure analysis of the engine system based on industry standard practices. We categorized possible failures as electrical, mechanical, software or environmental. We suggested possible solutions to avoid identified failures, such as using proper EMI filters, alternate components, new circuits or IPC standard PCB guidelines. The client was especially pleased with the understanding and consultation we provided regarding product performance and potential real-life failure scenarios we determined and resolved.
  • Phase 4: Implementation — New design suggestions, design updates and CAD update

    Based on our review findings and analysis, EASi completed the detailed reliability report, failure rate calculations, fault tree analysis, schematic updates, design changes, PCB redesign and testing.

The results
EASi delivered in-depth analysis reports for design, schematic, PCB layout, reliability and FTA, which have given this client deep confidence in the reliability of its new system design. EASi completed all phases of this project ahead of schedule by conducting weekly tracking touchpoints with the client during which activities, key updates, open items and design changes were discussed and reviewed.  Additionally, the proper documentation that EASi aggregated was a huge value-add to the customer, as quality and compliance considerations are held in high regard in the aerospace and defense industry.

The documentation gathered included a detailed system-level reliability report, fault tree analysis report, electrical design recommendations and changes and a software static analysis report. We exceeded client expectations in each phase by providing detailed analysis results, additional inputs and value additions. Most specifically, we were able to provide a 0-100 degree Celsius temperature report, which provided a deeper insight into the product’s reliability analysis. This prototype has since been completed and is expected to launch on the market by the end of 2019.