fan belt

Hi,

My TD5 110 was towing today, when the top pulley on the belt seemed to give way, and ruined my evening, when the belt got shredded across the engine bay.

I wouldn't mind, but this is the second time its happened, and the same pulley failed, even with the trailer (I got more miles out of it this time though) i wasn't putting any extra strain on it though...

So to summarise, brand new parts ( both OEM) is this a normal fault?

thanks,
Chris