Root cause analysis of two years breakdown data of a Beverage Company in Nigeria reviews that man and method are the predominant cause of failures in a production system. This further relates to the competence of maintenance personnel.

This study adopts a method based on the implementation of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section XI Appendix VIII) (Boiler and Committee, 1962) integrated to a delay time model to analyze and predict the expected downtime from different technicians based on capability.  As a large series of tests was not feasible, a smaller “weed out” 8/10 test was designed using binomial power curves to determine the probability of perfect inspection (PPI).

Numerical analysis shows that as the competence of a technician drops, there is a disproportionate increase in the proportion of downtime.  For a given cycle of 24 hours, when an inspection is been carried out by a technician with a probability of detection (POD) of 0.8, the expected downtime is 1.8 hours. When this activity is performed by another with a POD of 0.65, the expected downtime is 4.2 hours. There is about a 56% increase in the proportion of downtime compared with the corresponding 24%   difference in POD score.