Management of Field Replaceable Units (FRU)

For the inventory controller, manufacturing, and document change control, field replaceable units (FRUs) are evil. Added SKUs, additional space requirements, documentation management, and possible disruptions to normal manufacturing flow are problems. To the field service personnel, the FRU is a time saving, frustration reducing, wonderful thing, when configured properly. When considering equipment that demands high availability, FRUs can effectively reduce
downtime.
It is a simple concept; reduce downtime and the available time is increased.
Availability = MTBF/(MTTR+MTBF)
MTBF=Mean Time Between Failures
MTTR=Mean Time To Repair
What is an FRU?
A field replaceable unit is a component that is configured to be installed into a piece of equipment while in the field. The component FRU may be an off the shelf unit that has no additional configuration or parts required for installation in the field. Therefore, it is the same part that is used in manufacturing. However, an FRU may require a significantly different configuration than a component that is used during manufacture. It has a physical configuration that is different from a manufacturing unit, or it may contain additional parts or consumables that are required for the installation. For example: a new cover that requires sealant may include a small container of sealant as part of the FRU or a part that is mounted with rivets in manufacturing may include self tapping screws for replacement. FRUs reduce errors and missing parts while servicing in the field and reduces potential sourcing time for the servicer.
There are a few different methods of managing field replaceable units depending on the number of FRUs required and inventory management.
Preconfigured FRUs
Units that are prepared as a complete unit for field replacement is the quickest method for the field servicer and shipment of the unit. However, it is the most expensive, risky, and time consuming for inventory control and manufacturing. A single box with all the required parts, consumables, and a component configured to plug into the equipment with the least amount of effort is the easiest way to reduce downtime. These FRUs must be well thought out and may contain parts that are not used in the field installation, but are in the kit to ensure that there is no question the servicer does not have to source parts. Configurations may include wire terminations and fittings that are installed onto the component to allow the servicer to directly plug the component into the equipment.
Listed FRUs
A FRU configuration list may be used to reduce inventory demands, reduce disruptions to standard manufacturing, and reduce budget risk. Where multiple configurations in the field exist, it is the quickest method to deliver a custom shipment. For example, when a pump is changed a filter may be included in the FRU list to inform the shipper or order processor to include the filter when shipping the replacement pump. Equipment in the field may have different filter configurations and identifying the correct configuration in the order process allows only the correct filter to be shipped with the pump. Two boxes are then shipped, and configuration time is reduced. Listed FRUs still require document management time, but manufacturing, inventory control, and inventory space are reduced.
A combination of strategies may be used to best control FRU inventory, manufacturing time, and service time. In the case where special procedures, tools, or manufacturing practices are required, preconfigured FRUs are the only alternative. In addition to reducing time to repair, there are other factors such as logistical delay that can affect MTTR.
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Configuration,Failures,Errors,Downtime