What’s that odd noise, that ticking sound, coming from your v-belt driven fan? Man, you know the PM crew just changed the drive belts out; it can’t be the belts, so it has to be a fan bearing, right? You better get a shutdown to change the bearing out, and while you’re at it you might as well change both bearings out.
But before you do that, stop and think about it. You weren't there when the PM crew changed the drive belts out.
Did they properly install the belts?
Did they check for worn sheaves?
Did they spin the belts on without loosening the motor stretching and breaking the tensile cords?
You get the picture. Don’t take anything for granted. Don’t assume that just because someone told you that when you hear “that sound” it will always be worn/failing bearings. I will tell you from 35 years of past experience that less than 10% of the time it is a bearing problem.
If you do everything right, from the fan foundation right up to correct belt tensioning and sheave alignment it eliminates a lot of maybes. Only after you've checked into those possibilities you can start looking into possible bearing faults. Next time you hear that sound, check these simple things before planning to change a bearing and it could save you a lot of time and money in the future.