Both of these incidents feature heavily in human factors courses, and have lead to changes in practices that are designed to prevent re-occurrence.
yet they still keep happening and this time on a 21st century helicopter!
So what is not working?
Is it the fault of the designers who after making helos for many years still can't fool-proof critical systems from poor engineering practices?
Is it the fault of the documentation?
Is the the fault of the engineers who are not trained properly?
Is it the fault of the time-pressures brought by the management to get the engineering done asap?
Is it a fault of the operators for not paying decent wages to attract quality engineers?
Is it the fault of the aircrew who should be diligent and thorough on their walkrounds?
I suspect, like all incidents, there is a mixture of more than one fault (the old swiss cheese analogy) but whatever the reason, all the corporate knowledge, the 'lessons learned', the extra training in human factors and all the other mitigation measures have failed in this case - only the skill of the pilot stopped this being a fatal accident.