Perhaps a mental model abstracted from aerospace is you have a somewhat complicated PID controller and it was programmed to tolerate widgets with size of 0.01 to 0.02 because only those can physically fit on the assembly line, and within those limits it is proven and tested to be unconditionally stable and predictable and correct under all operating conditions.
Unfortunately manufacturing let a batch of 0.0201 size slip thru inspection, they just barely fit on the assembly line despite being out of spec too large, and the PID controller makes the system go into oscillation and explode because its outside its theoretical limits of whats possible.
The most insidious spec violations are "manufactured too well" if for example you rely on frictional damping to eliminate oscillations, then making and shipping better ball bearings than you'd ever shipped before, could ruin an overall system because one component is too good. Possibly the "error" is something is too smooth, too straight, too flat, or too low friction. No one ever expects those to cause a disaster, but it can happen.
That would be an example of a disaster involving software, that can be fixed in software, although it wasn't caused by the software, it was caused by bad control system engineering design work. Also this abstract example probably has nothing to do with the real problem, although the "widget" and "size" could very well be something line fuel line tubing inside diameter.
The original speaks of quality problems in the manufacturing plant. This is very general and could include problems in the design phase up to the flashing of the module after assembly of the plane.
I think the OP was reacting to the use of the term "quality problem" to describe a catastrophic failure leading to loss of human life. At least, that was my response when reading that quote.
