[daepp]

They make garage-door-opener bulbs that have stronger filaments because of the shaking they take. Is your fan balanced? Could it be that they are getting shaken too much.

Hijack - I have a stationary fixture that house three lamps in three equidistant sockets. The same bulb always burns out, and I am at a complete loss to say why. They are all identical to the eye - the other two have not burned out in the three years since installation!!!