Reactive Maintenance. If it works, don’t fix it

Reactive maintenance is done when equipment needs it. Inspection with human senses or instrumentation is necessary, with thresholds established to indicate when potential problems start. Human decisions are required to establish those standards in advance so that inspection or automatic detection can determine when the threshold limit has been exceeded. Obviously, a relatively slow deterioration before failure is detectable by condition monitoring, whereas rapid, catastrophic modes of failure may not be detected. Great advances in electronics and sensor technology are being made.
Also needed is a change in the human thought process. Inspection and monitoring should include disassembly of equipment only when a problem is detected.
The following are general rules for on-condition maintenance:
Inspect critical components.
Regard safety as paramount.
Repair defects.
And of course, If it works, don’t fix it.
Maintenance Fundamentals Second Edition
R. Keith Mobley