Blade CP Pro tail motor revving in flight

[Rick1958]

Is this normal, in flight...hover most of the time, I can hear the tail motor rev up in pulses, maybe a burst about 2 sec. long.... is this common? the tail stays straight during this.... brushes going bad??
:?:

[carlo_the_wonder_frog]

normal, its just the gyro speeding the motor up and down to counter any yaw.