Are you using fan rated bulbs?

No matter how smooth the operation appears fans produce vibration that can quickly kill bulbs.

The longer the hanging rods the worse the problem usually gets.

I haven't been using the fan during the winter and the bulbs keep burning out. The bulbs in the other three fans last forever. I'm going to try changing the wall switch and see if maybe that will help.

I'd still vote for vibration killing the bulbs, especially since you've replaced the fan twice. Is there anything special about the switch? The fact that the bulbs are brighter, then dim after a few seconds, implies that you might have a malfunctioning dimmer switch. But that shouldn't affect the life expectancy of the bulbs.

You could have a bad connection in the fan or at the ceiling box. It sort of behaves like a floating neutral or tied in series (light and fan neutrals).

Changing the switch didn't help so I guess I'll have to check all the connections in the ceiling box like you suggested. I'll have to do that next Tuesday as I won't be able to get to it until then. I'll let you know then.

Well I lowered the ceiling fan and checked all the connections in the celing box and in the fan itself. The bulbs still go dimmer after a few vseconds after applying power. I went up into the attic and checked all the connections there and they still go dime but up there is a junction box where all the ceiling lights and fans are bundled together with a big wire nut that it may be possible one wire is loose. so my next step will be to break the big bundles down into smaller bundles to see if that is where the problem is. But first I am going to email Hunter and ask them if that is what there fans a suppose to do.