Comment by jacquesm
10 hours ago
A more likely metric for this particular inspection would be hours or cycles, in other words starts and landings, not 'miles'.
10 hours ago
A more likely metric for this particular inspection would be hours or cycles, in other words starts and landings, not 'miles'.
According to various comments the plane was nowhere near the cycling for a special detailed inspection of the aft pylon mount lugs: SDI is at 29200 cycles and the plane had 21043.
There was a lubrication task in October, but according to tech comments that would just in greasing the zero fittings, no taking apart anything.
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.
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Zerk fittings, not zero (stupid autocorrect), the grease fittings.