Ken,
Like everybody here, I’m sorry for your failure, and happy that you were not hurt. I am a VP at a destructive testing laboratory in SoCal. While it is interesting to guess at the cause of the failure, it cannot be determined by looking at photographs. And to suggest that and entire lot of parts is suspect is unfair. Investigate: yes, accuse, no.
With that said, I would be happy to perform a failure analysis on the suspect parts, free of charge. If you are interested, email me and we will set it up.
Let’s hold judgment and comment until we have a clearer picture on what has happened.
Jason
jasonw@metalstec.com