The newly published Electrical Wiring Interconnect System (EWIS) Integrity Program Handbook (MIL-HDBK-525) provides a comprehensive method for assessing an aircraft’s EWIS condition for service life extension and ensuring continued airworthiness. There has not been a consistent method by which maintainers have determined the EWIS system health of their platforms, leaving each group to develop their own means for assessment. The EWIS Integrity Program strives to achieve consistency by providing the necessary guidance to utilize aircraft data (maintenance, data availability, financial constraints, etc.) to determine the most accurate EWIS component life span.
The reliability of system components impacts the aircraft airworthiness and the service/maintenance lifecycle. The EWIS integrity program provides guidance to determine the lifecycle for EWIS component and sets the objective of developing a sustainment and/or replacement program for each. At the completion of the EWIS assessment, a fleet level EWIS sustainability plan is generated defining the necessary actions to minimize EWIS issues over the remaining service life.
The MIL-HDBK-525 handbook derives many of its processes from those developed by the FAA. This regulatory guidance has been reworked to address military fleet sustainment activities. Because of this, the EWIS Handbook applies the most important principles of effectively identifying and implementing maintenance actions to achieve increased aircraft airworthiness.
The handbook is divided into seven core tasks which are essential processes in assessing EWIS condition. (Those familiar with FAA AC25.1701 will see numerous similarities in the flowchart presented below).
Task #1: EWIS Documentation:
Document overall EWIS and identify critical paths and functions. You can read more on this topic in the MIL-HDBK-525 EWIS Overview – Task 1: EWIS Documentation article.
Task #2: Data Analysis:
Collect and analyze EWIS failure and maintenance data. You can read more on this topic in the MIL-HDBK-525 EWIS Overview – Task 2: Task Analysis for EWIS article.
Task #3: Physical Aircraft Inspection:
Conduct an on aircraft physical and electrical inspection and document overall condition of the aircraft EWIS. Results of this task may be used to identify and target critical problem areas for EWIS initiatives or further evaluation. You can read more on this topin in the MIL-HDBK-525 EWIS Overview – Task 3: EWIS Assessment article.
Task #4: Component Assessment:
Conduct a comprehensive materials/aging analysis of wiring and electrical components removed from the aircraft based on information gathered in earlier tasks. You can read more on this topic in the MIL-HDBK-525 EWIS Overview – Task 4: Component Assessment article.
Task #5: Risk Assessment:
Analyze and provide an overall risk and life assessment of the aircraft electrical systems using findings from the first four tasks. You can read more on this topic in the MIL-HDBK-525 EWIS Overview – Task 5: Risk Assessment article.
Task #6: Action Plan:
Apply overall analysis toward an action plan (e.g. no changes, implement continuous inspections, partial or total replacement, implement new technologies). This topic is covered in more detail in the MIL-HDBK-525 EWIS Overview – Task 6: Action Plan Part I, and MIL-HDBK-525 EWIS Overview – Task 6: Action Plan Part II articles.
Task #7: Iterative EWIS Assessment:
Tailor and apply tasks #1-6 iteratively as required to reassess EWIS and to ensure desired outcomes have been achieved and maintained. The tailoring and iterative application should also consider changes in platform specific program direction and changes to operational requirements such as service life mission, etc.
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