Investigation focuses on cracked engine mount components that went undetected during maintenance on the 34-year-old MD-11.

The nature of the recommendations made by Boeing and the FAA in 2011 may have allowed UPS Flight 2976 to crash over 14 years later.

The UPS plane crashed in Louisville, Ky., in November shortly after takeoff, when the left engine flew off the wing. Fifteen people were killed.

Boeing (BA) had flagged past failures of a structural component later found cracked on the cargo jet involved in November’s fatal United Parcel Service (UPS) crash, according to a mid-investigation update from U.

Boeing issued a 2011 service bulletin warning MD-11 operators about potential spherical bearing assembly failures in engine pylons, the same component now at the centre of the NTSB investigation into November's fatal UPS MD-11F crash in Louisville that killed 14 people.