NTSB says Boeing issued service advisory in 2011 on MD-11 part

WASHINGTON, Jan 14 (Reuters) - The National Transportation Safety Board said on Wednesday that a key part of a UPS UPS.NMD-11 cargo jet that crashed in November in Kentucky, killing 15 people, that was found to have cracks was the subject of a 2011 Boeing service letter.

The NTSB said its investigation to date has found fatigue cracks in a support structure on the left pylon, which connects to the wing and the plane's engine, known as the bearing race.

Boeing's 2011 letter said there had been four previous failures of the bearing race in three airplanes but did not consider it to be a safety of flight issue, the NTSB said. The MD-11 remains grounded since the crash.