Following investigations in the aftermath of Flight TWA800 and Swissair 111 a detailed investigation was performed by the Ageing Transport System Rulemaking Advisory Committee ATSRAC into the effectiveness of the Inspection Process carried out during maintenance activities.
There was a number of shortcomings observed and finally this has translated into the need for specific training to manage inspection standards.
In addition an easy to remember phase has been coined which should be shared amongst the work force EWIS Maintenance Practice should include “Protect and Clean as You Go” (to ensure all possible contaminants are removed at source)
When we consider the challenges of Electrical Wiring Interconnect System Inspection Standards we may appreciate that there are limitations as to the effectiveness of the Visual Inspection process so every effort should be made to support the most effective methods possible.
The most effective EWIS organisational standard provides for a combination of techniques including visual – additional maintenance practices – improved training including practical training inspection techniques specifically for EWIS Inspectors.
To deliver a General Visual Inspection (GVI) during EWIS Inspections requires we are within touching distance Note that this is actually a pre requisite (unless otherwise specified). The GVI may be supported by the use of a mirror which may be necessary to ensure visual access to all exposed surfaces in the inspection area.
Regarding lighting requirements it is normal for the inspection to be made under existing or normally available lighting.
Some general considerations and observations to pay attention to during you inspection of aircraft EWIS
Looms which are not supported can sag and incorrect use of tie wraps within the loom can cause chafing and in fact tie wraps should be around the entire loom
P Clip Migration – all P Clips should be of the correct size and firmly attached to the entire loom Tie Wraps can age harden fatigue and fail – pay particular attention during Inspection
Any point of contact can allow wiring to chafe – so pay close attention during your inspection
Remember Human factors and effective inspection – take frequent brakes during the inspection –focus 100% on what you see. Share what you find with colleagues – raising the standard.
It is most important to ensure that all clips secure the cables effectively otherwise chafing can occur
No pressure should exist between electrical p clips and fittings – fixtures, pipes or tubing
The integrity of sleeving designed to prevent the ingress of fluids and moisture into connectors must be ensured
P Clips must be correct IAW IPC or other approved data and must afford appropriate support and protection, oversize P Clips pose a threat.
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