This is a series that will give you an EWIS overview. This article is the fourth in the series devoted to reviewing the guidance provided in MIL-HDBK-525 for Electrical Wire Interconnection System (EWIS) Service Life Extension Programs (SLEPs). If you missed one, here are the links to be previous articles:
- MIL-HDBK-525 Overview
- MIL-HDBK-525 Overview – Task 1: EWIS Documentation
- MIL-HDBK-525 Overview – Task 2: Data Analysis
Covered in this article is task #3 guidance, physical aircraft inspection. Applying the SLEP handbook guidance will improve the likelihood of properly identifying and correcting EWIS degradation issues. The basis for the guidance in task #3 comes from an amalgamation of military, industry, and regulatory publications on EWIS investigation procedures.
The principal causes of EWIS component degradation are identified as follows: vibration, moisture, maintenance, metal shavings and debris, repairs, indirect damage, contamination, and extreme temperature. Each factor has a different degradation effect on EWIS components, however all must be considered when performing physical aircraft inspections.
There are three types of inspections that are utilized when performing physical aircraft inspections. A detailed inspection (DET) is an intensive examination of a specific item, installation, or assembly. When performing a DET, inspection aids such as mirrors, flashlights, and magnifying lenses are highly recommended. A general visual inspection (GVI) is a visual examination of an interior or exterior area, installation or assembly. When performing a GVI, no equipment is removed and the inspector should be within physical touching distance of the equipment. Lastly, a zonal inspection utilizes a combination of DETs and GVIs, applied to a specific aircraft zone, in order to conclude component integrity within the zone. Details on visual examination techniques are included in the handbook.
The next article (Task 4) discusses the assessment of individual EWIS components to determine the current and future condition of the fleet’s EWIS.