You know, it coudl also have been just that particular defective aircraft, but then again, in the realm of investigation, such a notion would not be considered.
Because there's no such thing as a "defective aircraft", at least not in the implied terms here. There could be a particular part that's defective, but something, somewhere, caused
that defect. It is not acceptable to say "in our manufacturing process, there is the possibility that 1% of all parts we make will be defective during manufacture, will not be caught in the QC
and testing process and could cause a crash." Such a manufacturer would not be certified to build airplane parts.
All parts are tested and inspected prior to being installed. If the manufacturer made a mistake, they will be held accountable. If the inspection team made a mistake, they will be held accountable. If the design team made a mistake, they will be held accountable.
There is no situation in which you can just say "oh well, defective airplane, these things happen". There is a reason why defects are introduced into the process, whether it be because of poor design, poor manufacturing processes, poor inspection, or poor maintenance.
Anyway, if you've been following the NTSB's investigation (which has been a very public investigation), I see no chance that any part on this plane was defective. The NTSB has clearly been looking at both AA
pilot training, the actions of these particular pilots, and the design and certification process of the A300. My guess is still that some combination of these factors will be blamed in the final report, which is due (I think?) at the end of this month.
And yes, the NTSB does check for defects, and many crashes have been caused by and blamed on defective parts (check the Sioux City DC-10 crash for one example). The NTSB did check the bolts, the mounts, and the composite material itself on this particular tail for defects. But there are supposed to be procedures in place for keeping defective parts out of airplanes anyway so if a defect causes a crash, it means there was a systemic breakdown somewhere in the process; the part itself is not the root cause of the accident, the breakdown in the system is the root cause of the accident.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!