Tailstrike
Tailstrike or a tailscrape. As someone said it is very hard to detect from the cockpit. A friend of mine flying in Africa was saying that their company had 2 tailscrapes within a few weeks on 767. Apparently next crew and maintenance only saw it on the tailskid during their walkarounds. I am not familiar with the 767 at all but I understand that with a good dragging of the tail feathers this strut will compress. I was told that a pad at the bottom of the skid had just some paint missing, no other damage.
The 747 on the other hand does not have a tailskid even as the tail clearance is only a few inches.
JJ