How do we know that the steam turbine requires blade inspection even the schedule inspection is months away?

viberation

we can know by checking the wheel chamber pressure and vibrations, these2 parameters gives a clear picture of turbine blade inspections. For a steam input of70-100% an increase in wheel chamber pressure by10% indicates the deposition in blades in turbines.High vibrations also indicating the miss alignment of turbine blades due to the deposits in blades.