Very interesting. I've just never seen a chunk of aluminum break out of a sheet like that. While the cracked welds of the early Stage V's have been documented several times, until now there has never been a reported case of the plate actually breaking that I know of. The question for those folks that have the early edition Stage V's, is this just an isolated incident, or is this a risk that could legitimately occur to them. Can't be that many early edition Stage V's running around before the upgraded plate/welding went into effect. You Stage V folks can probably call Steigemeier to see if your model has the thinner plate since I'm sure they have documentation on this.There is no telling what alloy it is. I can tell you this though. 6061 or 6063 or T-6 Aluminum will not break like that. You would not see a chunk fall out of it. That Aluminum in that pic is junk aluminum with a high/low content of alloying elements. Manganese, silicon, copper, nickel etc.