Large monolithic parts are harder to repair. That's the upside to the current setup of panels riveted to a frame. Any one of those panels can be drilled out a

Large monolithic parts are harder to repair. That's the upside to the current setup of panels riveted to a frame. Any one of those panels can be drilled out and replaced. Boeing has a special team called "AOG" (aircraft on ground) that will go out to a repairable aircraft that isn't airworthy and make it so. Kind of hard to do that when you need to bring along a megaton autoclave and portable cleanroom.