seems 051 is back after that fuselage fracture.
fuselage seems to be strengthened, that yellowish part
good to see her again
Correct the yellow is just the zinc-chromate over all the work that has been done, those skins cover the repaired/replaced aft main gear bulkhead, maybe at station 23?? I believe prolly new heavier bulk head, maybe just a patch? upper fuselage longerons likely strengthened? stringers, floors?? note how thin that aft fuse section is??? and there is an aft weapons bay that comprises a lot of "dead space that is structurally a liability, when you factor that in to the tremendous stresses of pushing that airplane around the sky with those OVT nozzles, much of that side loads?? and vertical stresses up and down, right and left opposing nozzles as you roll? there is a lot going on back there, no doubt they have a handle on it now, and these mods, upgrades will be rolled into the production aircraft, heavier skins are also in that mix, that's why we build and fly prototypes, and then push them till they break, and they do break.
To put all this in perspective, the F-35B has very similar issues with the aft main bulkhead that was changed to aluminum after being designed to be Titanium, the A and C still have a titanium aft main bulkhead, no cracking there, but problems with the leading edge root ribs?? and who knows what else, burning off the tail feathers with afterburner, its all fun and games, especially when you have to go back and rebuild parts of these birds?