By David Shepardson and Allison Lampert
WASHINGTON, Jan 14 (Reuters) - A cracked part found on a UPS MD-11 cargo jet that crashed in November in Kentucky was flagged in a Boeing service letter more than a decade earlier, the National Transportation Safety Board said on Wednesday.
Fifteen people, including three plane crew members, died in the fiery crash at Louisville Airport in an incident that led to the grounding of the MD-11 cargo jet model.
The NTSB said its investigation has found fatigue cracks
in a support structure on the left pylon that 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 that required visual inspections but did not consider it to be a safety-of-flight issue, the NTSB said. The part would typically be inspected every five years, Boeing's letter said.
The FAA declined to comment. Boeing said it continues to support the investigation led by the NTSB but did not comment on the letter.
Air safety expert Anthony Brickhouse said the Boeing service bulletin cited in the update flagged a fatigue situation.
“If fatigue isn’t handled properly, obviously it can become a safety-of-flight issue," Brickhouse said.
The NTSB's update also said the first engine of the UPS plane caught fire, while there were some anomalies in the thrust of the second engine.
Normally, a three-engine plane operating with two fully working engines should be able to climb.
Investigators will be looking at possible ingestion of debris, experts say.
(Reporting by David Shepardson in Washington and Allison Lampert in Montreal)
