Carrier chiller condenser fan problems

[will smith]

I ran across a Carrier Model 30RBB13064-5-7-3 today...had 2 condenser fans with the center hubs split in half, spinning wildly and generally making enough noise to make you want run for cover. These fan assemblies are made of plastic, and bolt on to the the motor shaft. They have keyways, but no setscrews. We just took this chiller under contract recently, not much service info left from previous service provider, other than a note that a fan/motor had been replaced 5-2-11 for the same reason. I won't give the exact price for two motors/blades we're getting hit with, but I will describe it generally as a mortgage payment. With a car payment to boot.
Anyway-has anyone run across problems on this model-or with other units with the same type of blade assembly? I'd be thinking loose mounts causing wobble and stress-only everything is tight. Likewise, the bolts securing the blades to the shafts were tight. Also no indication of short cycling.

[Dallas Duster]

Motor bearings were all good?

[will smith]

Bearings good, couldn't see any wobble in the shaft.

[nique]

I've got a dozon or so of those units and have worked on many more and have never had that problem. I really like the way those are setup, so easy to work on. I could not find a sb on it either. maybe the bolt was overtighted. if you figure it out let us know.

[will smith]

Thanks for the input With the sticker shock for the replacement, I was hoping this was just a fluke. Will certainly check the torque specs when the new ones go on.

[southparks]

Havent had any issues, sounds like a fluke to me.

[VAroadking]

i have started and serviced alot of these chillers and only had 1 fan with this problem, good luck.

[will smith]

Thanks VAroadking-
I changed the motors and blades, and made sure ALL the fans were torqued to Carrier listed specs. The previous service provider lost another motor/blade on this unit almost exactly a year to the day I found the two failed the same day...Stuff like that always makes the short hairs on the back of my neck stand up.