Yesterday for the third time in less than a year I had to go to a job in which a blower in a Trane commercial air handler simply flew apart, and make a temporary S.A. feed from a temporary unit into the duct for the downed air handler. All three units have been of different tonnages and all over the 100 ton range. The one I went on yesterday was actually the second blower they put in that particular unit. When the first one went, they were able to get it fixed within a day or so. But then a week later, that one went also which is where the temp. unit came in 'cause they have to wait a week for this next one to come in. The first unit this happened to the shaft actually sheered in two. Is this a strange co-incidence or has anyone else been hearing of stuff like this happening?