The factory has four major production lines. These involve a complex series of processes, all of which are under PLC control. Line Three has had repeated downtime episodes.
The plant manager personally asks you to get to the bottom of things. He shows you a printout from the CMMS. One chart shows the average repair time decreasing over the past year. "This is good. I love efficiency," he says. But then he flips to the next chart. It shows the number of downtime incidents. "This isn't so good. We're fixing things faster, but we're not stopping the failures with this line."
How can you solve this problem?
The increasing speed of the repairs is a sign that the repair techs are taking shortcuts. So you need to determine if the repair techs are performing the repairs more efficiently or just faster. Each proper repair should reduce the downtime incident rate. But repairs that take less time due to rushing or taking shortcuts tend to leave ticking time bombs of failure.
Given what you've been told, it's likely that the repair techs have left a trail of human errors behind them. Interview the techs who conducted the repairs. Ask them to show you, dry-run style, what specifically they did differently from earlier to reduce the repair time. Where is that time-savings coming from?
One common time-saving shortcut is to forego the use of a torque wrench when tightening terminations. Conduct thermal imaging to reveal which connections have been damaged by this bad practice.