Inspect whether the operation condition of the fan (centrifugal fan, high temperature fan, mine fan, roof fan, fan model selection and axial-flow fan) is normal, and promptly find out the problems in case of fault. 

1. Whether there is the oil leakage and water leakage in the operation. The reason may be the oil seal gap and leakage point; 

2. Whether there is the air leakage in the operation. The air leakage could be checked in the air leakage point, aging condition of solid piece and tightening degree; 

3. Temperature of bearing in operation. Check the wear pattern of bearing, magnitude of interference of bearing cover, oil pressure and oil mass; 

4. Vibration condition of unit in operation. Inspect the coaxiality, bearing clearance, bearing contact, rotor balancing, gear wear, etc.