Yes, the inspection process - from Wikipedia :

The investigation, while praising the actions of the flight crew for saving lives, would later identify the cause of the accident as a failure by United Airlines maintenance processes and personnel to detect an existing fatigue crack.[1] Post-crash analysis of the crack surfaces showed the presence of a penetrating fluorescent dye used to detect cracks during maintenance. The presence of the dye indicated that the crack was present and should have been detected at a prior inspection. The detection failure arose from poor attention to human factors in United Airlines' specification of maintenance processes.[1]