MIL-HDBK-525 EWIS overview: Task 5 — Risk assessment
We are presenting an EWIS overview. This is the sixth article in the series on 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
- MIL-HDBK-525 Overview – Task 3: EWIS Inspection
- MIL-HDBK-525 Overview - Task 4: Component Assessment
In task #5 of the MIL-HDBK-525, the focus is on the development of an EWIS risk assessment based on the data collected in Tasks 1-4. In practice, this stage applies common risk assessment processes (further details on general risk assessments process can be found in MIL-STD-882).
| PROBABILITY | SEVERITY | |||
|---|---|---|---|---|
| Catastrophic (1) | Critical (2) | Marginal (3) | Negligible (4) | |
| Frequent (1) | High | High | Serious | Medium |
| Probable (2) | High | High | Serious | Medium |
| Occasional (3) | High | Serious | Medium | Low |
| Remote (4) | Serious | Medium | Medium | Low |
| Improbable (5) | Medium | Medium | Medium | Low |
| Eliminated (6) | Eliminated | |||
The data collected from maintenance and degradation results (Task 2 and 4) are categorized into a probability of failure (1-6), with a rank of ‘1’ given to failures that can be defined as ‘frequent’; guidance is provided in the handbook on how these should be combined. The failure severity, based on the assessments in task #1 and some of maintenance reports from task #2, is assigned one of four categories.
The risk assessment matrix provides beneficial information in the selection of which EWIS components should be addressed and mitigated immediately. The risk assessment can be performed at the device level, wiring harness, system and/or aircraft level in order to determine individual risk sources to be evaluated in Task 6.
If the risk assessment results are determined to be unsafe in the Risk Tolerance section (Task 6), modifications to the risk assessment shall be made according to the mitigation strategies developed in Task 6.