> if that was the argument, then that would also mean that we shouldn’t allow any newly built 8s and 9s to enter service, and I don’t see that happening
Yes, that's a fair point, although doing that would require some sort of modification of the existing certification of 8s and 9s, and I'm not sure how that would work. If those certifications were simply revoked, all 8s and 9s already in service would be grounded until the issue was fixed. But if they are simply left alone, new 8s and 9s can come into service since those variants are certified. An Airworthiness Directive, which is what is currently issued by the FAA for 8s and 9s, by itself doesn't prevent new units from coming into service.
Yes, that's a fair point, although doing that would require some sort of modification of the existing certification of 8s and 9s, and I'm not sure how that would work. If those certifications were simply revoked, all 8s and 9s already in service would be grounded until the issue was fixed. But if they are simply left alone, new 8s and 9s can come into service since those variants are certified. An Airworthiness Directive, which is what is currently issued by the FAA for 8s and 9s, by itself doesn't prevent new units from coming into service.