IFEZ is quite right – we all depend upon our maintenance outfits to an extent which we seldom appreciate, possibly because the safety record is generally very good.
But our maintenance outfits depend upon their parts suppliers (if parts are available at all.)
And the parts suppliers depend upon the manufacturers of the parts, who need meaningful design documentation to work from.
And the manufacturers depend upon their raw material suppliers who have to supply metals to the required specifications.
And on their heat treatment people.
And on the electroplaters and the NDT specialists.
And so on. They all have to operate proper inspection processes and certify the results.
That is before you start altering the basic design by bringing in substitute materials with different tensile strengths, notch sensitivities, fatigue characteristics and maybe different manufacturing techniques.
So CASA should have been monitoring all this to make sure it was being done properly, but instead seem to have abandoned their supervisory role for reasons which were no doubt good ones so far as they were concerned.
This does not just apply to old aircraft with a long (and probably very safe) history. The ATSB Report mentions over 1000 other parts made by this same company for other aircraft, some of them in the Commercial Air Transport category. Are we going to see a general recall of all these parts for inspection? Who wants to fly in a VH reg. Embraer EMB 120 or a Fokker F28 right now?