Comment by contingencies
3 years ago
Many things failed, at least: (1) failure to identify safety-critical parts for review (2) failure in design drawings made without regard for fabrication (3) failure to make reference to original design goals when altering part designs (4) bad machining plan altering work-holding during the machining (5) failure to inspect finished parts
(5) was particularly bad: an off center hole should have been visible to the naked eye of any trained machinist, and at least one person should have inspected all safety critical parts. This would have been the final fail-safe to catch the combination of all prior errors. It was not made.
There's actually another failure - (6) - which is the failure to perform visual inspection of the assembling mechanic which should have generated a query or note at the very least. While at this point the mechanic is probably given specific points to check, and an aggressive timeline for assembly, and has little motivation to extend critical thinking beyond the assembly task as they cannot possibly intuit all of the design intent for every part and subassembly, a better run assembly process with a culture of observation would have had this flagged for verification with designers.