Temporary fix work orders

In a fleet of 40 haul trucks, a common work order type is triggered by a low level alarm of some fluid (for example, hydraulic, coolant, lubricant, air, etc). Sometimes some function will not perform adequately or at all due to insufficient fluid. The immediate quick fix will replenish the fluid and put the unit back into service. A few days later the problem repeats and the same fix is applied. The number of times this happens is monitored. After, say four or five repeats, the planning department issues a work order whose objective is to discover which failed part is responsible for the leak.

Quick fix work orders can be considered CBM observations or inspections of a sort. They are similar to non-rejuvenating repairs. Their rate of occurrence can be used to trigger a diagnostic work order as that described above. Assume that the cuprit is a particular seal. How should the information surrounding this failure be used to build a sample for Reliability Analysis?

Although there were five work orders, only the fifth located and corrected the single failure. Truthfully the failure occurred at the date of the first work order not the fifth where it was finally diagnosed. The offending seal may have been similarly detected in other trucks in the fleet. The consequences (average downtime and failure frequency) would be determined from the various work orders involved. The downtime would be that accumulated over all five work orders. With half a dozen detections of this type a data sample can be extracted and reliability analysis performed. A Weibull and cost analysis could be used to justify failure analysis leading to redesign. An EXAKT analysis could be performed to discover which, if any, monitored variables will allow detection and correction of the problem at the first work order rather than waiting for repetitive confirmation as is the practice.

© 2011, Murray Wiseman. All rights reserved.