If a wired assembly has been “tested” does it mean that it is definitely good? What about that bugbear of electrical assemblies – The matter of intermittent faults manifesting in electrical cable assemblies and wire harnesses?
Like most electronic assemblies, cable and wire harnesses are subject to manufacturing defects and it is standard procedure to electrically test them. Hard, (repetitive) failures are relatively easy to detect, and testing is an effective means to eliminate them. Soft, (intermittent) failures can be much more difficult to find. However, it is possible to improve product through testing by understanding the source of intermittents and attacking their root cause.
Since intermittent problems are just that, intermittent, they are much more difficult to find than solid defects and the best techniques for finding them are often overlooked. Sadly, most cable harness testers in use in the aerospace industry use old test point designs that require relays to switch from point to point and this technology cannot be expected to find fast intermittent connection problems.
A test engineer has to ask;
Will the harness tester, and the interface fixturing, support the detection of intermittent problems?
Can test data be utilised for feedback, and can appropriate action be taken to remove root causes, rather than just futilely attempting to “test quality into” assemblies.
Read our full article about testing for intermittent faults and our Recommended Action Plan.