Failures that occur during testing on the factory floor in controlled laboratory conditions or during product manufacture can be classified as "regular" failures, ones in which a significant amount of resources (people and test equipment) can be brought to bear on the problem. By contrast, field failures are those in which an assembly has failed in its normal working environment, often remote to the manufacturer, and where resources for analysis can be limited and must be transported to the jobsite. Field failures are particularly challenging. To help, here are some simple suggestions.
Prior to arrival, if asked by field personnel for permission to disassemble and return equipment to service before a thorough inspection by the failure analysis team takes place, resist the urge to say yes. It may be necessary to ship the assembly back to the factory in one piece for a more controlled analysis where more specialized resources may be available. If field disassembly is required, the failure analysis team should participate and not defer "hands on" work to technicians or less qualified individuals.