Whoa, that's nasty Mike! I've never heard of a fan coming apart at that low an rpm. Let's hope the head/cylinder fins and the cooler are all ok. Gene Berg does a welded/balanced fan
and while it's not cheap, you know it's done right. I have heard of guys using tig to melt the blade ends (and not add any rod) so the balance is not affected (great if the fan was already balanced) but if you have to buy a fan and then pay for it to be done I'd go with the Berg piece. I've heard of blades coming through engine lids (on bugs) so take a good look around to catch all the damage and I'm glad no one was hurt. Al
PS- pics of the alternator and stand! We need to see the carnage!