It may very well come down to a lack of lube of the pylon aft spherical bearing causing a vibration frequency that caused the lug to wear/fatigue crack. That fitting is hard to access and given the fact the md11 has been mostly vendor serviced it is possible due to its access, not properly lubed. IMO a failure of that aft bearing lug leading to a catastrophic failure is a poor design even if it were properly lubed. FedEx inspects that area every other C check. Every Four years.

I’m sure Boeing has no real interest in keeping the formally MDC product in service any more and a pylon redesign is to costly.

Best case scenario, drop all the pylons and engines, NDT lugs for cracks. Rebore lug replace bearings and increase inspection frequency. Make the Lube RII.

Worse case, put the thoroughbred to pasture.