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I replaced the left side aileron 90 degree bellcrank in my ES at 150 hours. It had significantly more play than the right side. The actual bearing had developed play, not the mounting of the bearing in the aluminum plates. I'm not sure if I didn't notice it a year earlier or whether it developed that much play in a year. I now thoroughly check for side play in all the bellcranks annually. Another ES had an aileron bellcrank bearing replaced due to excessive play at a couple hundred hours.
One factor is all the fiberglass dust that flies around during construction gets into the pre-lubricated bearings and causes wear. The bearings used in the bellcranks are not designed to handle significant side loads. Since the aileron bellcranks support the weight of the pushrods, that likely contributes to them wearing out more quickly. Another builder has investigated the possibility of the resonant frequency of the pushrod causing some vibration that would accelerate bearing wear, but no conclusive results.
Mike Easley
Colorado Springs
ES
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