The frame of the tailplane, the frame of the wings. It is inside the aircraft, if you like. It is not the sort of thing that you would see if you just walked up to an airport and had a look in an aircraft. It is right inside the aircraft. It is the main structure of the aircraft.
Engines actually tend to be in various ways checked far more often than airframes.
The maintenance system on engines is such that they get a much more frequent inspection. Part of that of course because they are - they have got a lot of moving parts, they work in very difficult environment, very hot, so really engines are a very different issue from the airframe. The airframes are, you know, harder to inspect and that is why it is important that the inspection program is put in place by the manufacturer. Anecdotally it may be worth, just for background, recognising that in the late 80s, 747s had a much bigger problem than this one with the 767 in terms of a cracking around the nose area around by the front door where the first class passengers get on. And, I mean, it was not a question of grounding 747s at that stage, but it was a question of putting in a process, and that process is actually a complete rebuild of the nose section of a 747 which is undertaken by all the old 747s when they come up to a certain number of take-offs and landings.