Check your Aerial Lifts

[joesawer]

Here is a write up of a accident. They are just as common as stirrup failure on your spurs, uncommon but can and will happen.

http://www.labour.gov.sk.ca/safety/bulletins/failure-bolts.htm

This link is for you techno junkies out there.

http://www.mech.uwa.edu.au/DANotes/threads/fatigue/fatigue.html

It seems very likely that something like this could have happened in this case. It is common to put a reconditioned boom on a new chassis.
I don't know it for a fact but I heard from a reputable source that the boom that fell with my friend was reconditioned and re certified and then put on a new chassis and was back on the row in a very short amount of time.