Hmmm
Don't know about you guys, but something doesn't look right from those pix.
If the airplane was just sitting there humming along with a tug and towbar hooked up, and someone threw the gear lever up with hyds pressurized (utilizing the override), the airplane would only fall about 4-6 feet. If the nose gear came up.
The idea being that the tow bar/tug combo should sorta stop the nose gear from moving forward. Not sure of the tug there, but it's gotta weigh at least 40,000 pounds. Round number there, but that sort of tug is usually HEAVY.
That sure looks like a LOT of damage from a let's say 8 foot fall from a static position. Heretics may believe that the 747 is made from tin foil, but I can say with some knowledge that the airplane is just a bit tougher than that.
We have the photos that show the result of whatever happened, that is not in question. That the lower section basically pancaked when it "fell" on a tractor? Well, there has to be more to this than we will probably ever know.
Conjecture...
It's all geometry. Draw a picture of the nose of an airplane with a nose gear sticking down. Attach a towbar to the gear and a tug. Now, try to move the gear forward and see what happens to the angle of the towbar and the gear considering that the airplane and the tug don't move.
The towbar and gear would act like a jack until the shear pins on the bar failed. Then...KA-WHUMP!
The question I have is: Considering that there SHOULD have been some sort of downlock pin installed (hopefully, a real one), what is the likelyhood that the downlock pin would fail and the hydraulics would have enough oomph to overcome the static force of the presumably chocked/braked aircraft and the braked tug to allow the aircraft to raise up and come down on the aforementioned tug?
Again, we have the pictures, so I'll leave you with this: Just because the likelyhood of something bad happening is most extremely remote, it doesn't mean that it probably won't happen.
I must tell you that I, as an Engineer, have in the past grasped the gear handle with hydraulics pressurised and raised that handle to the UP position whilst on the ground.
I haven't landed an aircraft yet.
It is a most unnerving thing to do, but there are occasions where the procedure is a welcome alternative to dragging the aircraft into the barn and jacking it up. Follow the procedures, use the correct equipment and it's unnerving but perfectly safe.
Weird stuff happens, ya just can't avoid it.
PB