[dylan604]

What's crazy to me is that these things do not roll of the factory line in large numbers. If it was a car plant or some other line where large numbers come off per shift, you could find that possibly one operator for one shift set their torque wrench to the wrong setting causing the finished items for that shift to be suspect. But seeing as not one plane rolls of the floor per shift, this is much more systemic like possibly the documentation was wrong or similar where it is persistently done incorrectly. Or maybe just the one plane for that one day that the worker incorrectly set their torque wrench that day.

[hef19898]

There is definetly one plabe rolling of FAL per shift. Airbus for example is aiming for a delivery rate of 60 single aisle planes per month.

[johnwalkr]

It can be opposite of your interpretation too. If you make 100,000 cars in a year, each step is done at least 100,000 times and it's justified to have a single wrench, with single non-adjustable torque value, and automated datalogging of applied value for a particular step. Or even a robotic process. Maybe even computer vision to check fastener length.

If you make 10 or 500 planes in a year, you have to rely on multiple people to use multiple torque wrenches, with multiple attachments, to follow multiple procedures to assemble multiple planes using fasteners of multiple lengths, nearby multiple other processes and people. There is a big emphasis on procedures and traceability but there are still so many potential failure points that can go undiscovered for a long time.