When should you consider adopting an aircraft wire insulation assessment program? Part VI
SubTopic: Determining the Severity of Failure for wire life extension.
A wire insulation assessment is a significant step forward in understanding the condition of the wire system and the topic of aircraft wire life extension for aerospace. However, to achieve a full system risk assessment, the assessment of probability of failure must be combined with the assessment of failure severity. To achieve this, the information about the aircraft’s electrical wire interconnection system must be examined.
The wire insulation assessment process starts with gathering data for the assessment. For a new aircraft, gathering this information is easy since all of the design drawings are available and the routing of the wiring is easy to determine. However, for an aircraft that has been in service for a number of years, the changes to the system can make the original engineering information obsolete. To address this loss of information, Lectromec developed a process for gathering the data. This process is quick and efficient and conducted in conjunction with the customer, thereby ensuring that all of the engineering data collected is correctly representative of the customer’s aircraft.
Some of the information to be gathered includes:
- Wire specification (cable specification): This determines subsequent age degradation model and impacts wire arc damage analysis
- Gauge:The power wire conductor size has a large impact on electrical arc damage
- Associated system: Important for collocation assessments and harness loss impact analysis
- Connection points: Important for wire termination points (from-to information)
- Connectors: Necessary for associating wire connections with harness end points
- Splices: Necessary for identifying electrical power propagation
- Relays: Necessary for identifying electrical power propagation
- Electrical Devices: Necessary for determining devices affected with loss of wiring
Lectromec has developed a number of software tools to stream; each integrated with the EWIS RAT technologies. An additional feature of these tools is that it gathers physical information about the wire routing. The physical routing throughout the aircraft is just as important as the wiring harness composition; this information cannot be gathered from wiring diagrams alone.
Furthermore, the physical routing of the wiring within the harnesses is critical to arc damage analysis. The potential arc damage is dependent on a number of factors which include (but are not limited to) distance from the generator, number of power wires in the harness, and the wire insulation type. Additional information that can be gathered from the harness examination provides the ability to effectively perform collocation analyses.
The system and physical data gathered is used for the severity of failure assessment, which will be covered in the next article.