Replacing the Alternator Drive Belt

Perhaps some of the experience engine folk i.e. Mahlon etc can advise on this subject.

What is the expected life in hours of engine operation of an alternator drive belt?

Should it be replaced say every 1000 hours or should one continue to use it with the hope of changing it at engine overhaul?

Should it be replaced as a precautionary measure every time one removes the prop?

I have recently bought a spare one to carry in the plane as I have an electronic ignition (Electroair) and a single magneto and I would not like to get stuck too far from home with an out of service alternator.

Any other thoughts or advice on this.

Barry

Barry,
I think the belt condition determines when it needs replacement.
During routine inspection if the belt shows heavy wear from not fitting the sheaves or alignment issues. Or it is stretched so it won?t tension properly, then it will need to be replaced more often the one that doesn't have those issues. Alignment on most aircraft engine alternators is pretty poor in most cases and even with that the belts last a phenomenally long time. If there are no cracks in the belt and it hasn't worn to the point of being close to bottoming in the v of either sheave, and it can be tensioned properly, I wouldn't replace it.
BTW some guys will stretch the replacement belt over the nose of the crankcase when the prop is off and tye wrap it out of the way. That way when and if the belt ever needs replacement in an out of the way place you don't have to remove the prop to replace it. Not to bad a job for the fixed pitch guys but for the constant peed guys taking the prop on and off to change the belt can be a real chore.
Good Luck,
Mahlon
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Or, how about adding a mechanically driven alternator from the accessory pad?