Boeing reports that the 30 or so 777X airframes that have already been built will require modifications before they can be delivered to airline customers. Perhaps being overly optimistic about its early design, whilst hoping to get deliveries started as soon as possible, the aircraft manufacturer went ahead and produced airframes prior to the type being fully certified. The result of all this is that some work will need to be done to these aircraft in order to make them compliant with certification specifications.