Comment by jacquesm
5 hours ago
Those pictures of that torn up part are pretty hefty, that's a clean break, no stretching as far as I can see it just tore the material in half, you can see the grain. There does not seem to be any torsion either so most likely that was the first part to go, if the problem had been in the engine then I would expect this part to be mangled, not pulled apart. What stress damage there is occurred shortly after that first break. A valid question would be whether or not that crack was there before take-off or not.
I'm very curious what the metallurgic analysis of the mirror part on the other wing will come up with, especially whether there are any signs of stress fractures in there. If there are that will have substantial consequences for the rest of the still flying MD11's, about 50 or so are still in service.
The preliminary report mentions fatigue cracks on both sides of the aft lug, and one side of the forward lug, with the other showing no trace of fatigue, only overstress.
From this it seems like the aft lug was way fucked, and the forward lug was hanging on for dear life, until it could not.
Yes, that's exactly how I read it. The aft lug was the first to go, the forward lug shows signs of stress so it held on longer.
I don't think they're going to be skimpy on the metallurgy report so looking forward to the analysis of the mirror parts on the other wing. Those will tell without a doubt whether it was maintenance related or age related fatigue. Right now I would bet on the latter but the former could also still be a factor, for instance, that bearing might not have had enough lubricant.