That whole inner cylinder is just gone from the outer cylinder.A big chunky gland nut keeps them mated together. Perhaps the whole cylinder broke(HSLA degradation), the gland nut gave away or some other issue developed. Sometimes these gland nuts are painted yellow which means they are a matched oversize set, that too could have been a factor.
Interesting incident, never seen anything like this.
Don’t forget I’m a pilot… Do you have any illustration that can help me understand?
Also, don’t know if you watched the video by Browne, but he mentions this airframe had an accident where this very landinggear bounced of the roof of a van. He also points out that the boogie hangs lower than the rest, in the video. Does this tell you anything?
There’s the diagram of an oleo strut which IIRC is what the 747 has, I am a bit rusty on the type so would need to look into it more this weekend if you have any specific questions.
You can see how big the body landing gear is when full extended. I don’t recall if the 74 has a shortening mechanism or not. I don’t think so. The A330 for example has a mechanism at the top of the piston(inner cylinder) inside the outer cylinder that allows it to shorten the gear thus having it take up less space inside the wheel well. The 747 doesn’t sit that high so it probably never needed it.
EDIT: Checked out the video you mentioned of the gear hitting a van and I doubt it’s relevant given that that happened 2 D-checks ago or there abouts, I wanna bet that truck has long since been replaced.