writes:

Bull****! The crack in the engine had absolutely nothing to do with
maintenance. It was a flaw that existed when the turbine blade was
fabricated. It was not detected in initial inspections of the parts
by the manufacturer, and there was no way that maintenance could have
ever detected it until it failed due to its microscopic nature. If
the manufacturer couldn't see it, what makes you think that Joe
mechanic should have tools that would allow him to see it?

A failure to see it is a failure to see it. It's not excusable.