I am seeing repeated fans failures on several of my S19s.
Not receiving much insight from Bitmain support.
Looking for insight to common (or uncommon) causes of fan failure.

Log entry looks like:

2021-04-16 05:13:19 Error, fan lost, only find 3 (< 4)
2021-04-16 05:13:19 fan_id = 0, fan_speed = 5880
2021-04-16 05:13:19 fan_id = 1, fan_speed = 0
2021-04-16 05:13:19 fan_id = 2, fan_speed = 5880
2021-04-16 05:13:19 fan_id = 3, fan_speed = 6000

another example:
 
2021-09-18 02:50:03 Error, fan lost, only find 3 (< 4)
2021-09-18 02:50:03 fan_id = 0, fan_speed = 13080
2021-09-18 02:50:03 fan_id = 1, fan_speed = 5880
2021-09-18 02:50:03 fan_id = 2, fan_speed = 8520
2021-09-18 02:50:03 fan_id = 3, fan_speed = 5880

I am seeing zero rpm all the way to 25k rpm - which is impossible - on fan failures. 6500 rpm seems to be the max on healthy fans.

The environment is clean air with sub <=23c (73f), clean power. My servers are less than 6 months old.

Are the fans disposable?

Regards.