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EWIS Risk Assessment Tool (EWIS RAT)

Summary of Electrical Wire Interconnection Systems Risk Assessment Tool (EWIS RAT™)

EWIS Risk Assessment Tool (EWIS RAT)
Take advantage of Lectromec’s experience with EWIS risk assessment and reduce the time and cost for certification.
  • Patented software tool capable of performing EWIS risk assessment to show aircraft safety compliance with FAA EWIS regulations (25.1709)
  • The EWIS RAT™ can integrate with your CAD models for rapid feedback on EWIS design
  • Addresses the physical and functional analysis needs of aircraft EWIS designers and certification authorities

Introduction to the EWIS RAT™

Lectromec has developed an Electrical Wire Interconnect Systems Risk Assessment Tool (EWIS RAT™) (Patent #7536284) designed as a package for aircraft manufacturers. The RAT™ simplifies the process of analyzing EWIS hazards, potential damage to structure, flammability issues, as well as provide type certification automation capabilities for aircraft electrical systems. This tool and methodology introduce a fresh perspective to the maintenance and upkeep of Electrical Wire Interconnect System (EWIS).

Problems and malfunctions of the wiring systems are broken down into categories, each identifying specific levels on which malfunctions can occur and the degree of severity. This can be an effective way to help address those needs resulting from Federal Aviation Administration (FAA) rule 25.1709 (formerly 25.1705) requirements. FAA Rule 25.1709 requires:

Each EWIS must be designed and installed so that:

  1. Each catastrophic failure condition
    1. is extremely improbable; and
    2. does not result from a single failure; and
  2. Each hazardous failure condition is extremely remote.

Lectromec’s twelve-year experience working on defining methods that comply with FAA 25.1709 has given us a thorough and unique understanding of the FAA 25.1709 requirements. The RAT™ facilitates evaluation of a particular wiring layout. Evaluation can be done during the original design to ensure adequate separation and segregation of aircraft wiring, thereby minimizing the potential for single point failure. The tool can also be used for assessing the safety of modifications to the original layout, as might be the case in the supplemental type certificate (STC) process.


Lectromec will work with your organization in the development of the documentation necessary to meet the requirements of EWIS certification. As all organizations have different methods for data storage and maintenance, Lectromec believes that the most efficient means of developing the documentation is for Lectromec to import, manipulate, translate, and modify the data such that it can be entered into the EWIS RAT™. This is designed as a ‘turn-key’ operation; one in which the data is provided to Lectromec and Lectromec will do all that is necessary to integrate the data properly. Lectromec will work with your planning teams to understand the particular characteristics of your design system and generate a timeline upon which the EWIS certification documents will be generated.

The best time to start the integration of the EWIS RAT™ system is as early in the design process as possible. Since the requirements of EWIS certification are new, there are a number of concepts that should be integrated early such that they not only are integrated into the current design, but help engineers understand the requirements and explore how the process can be improved in future design projects.

Additional Reading

The following information may of use to those looking to find out more the EWIS RAT and wire system risk assessment: