An aircraft that crashed in flames in Kentucky in November had a structural flaw that had been identified by Boeing on similar planes 15 years ago, according to investigators.
The MD-11F freighter operated by UPS crashed after one of its engines separated from the wing as it was preparing to take off from Louisville.
The plane briefly lifted off from the runway before hurtling out of control into an industrial area. Fifteen people died as a result, including three crew and 12 on the ground.
In an update report, the US National Transportation Safety Board (NTSB) revealed that cracks found in the engine mounting assembly had previously occurred on several other aircraft.
At the time, the manufacturer responsible for the aircraft, Boeing, concluded that the issue would not result in a safety of flight condition.
The MD-11 is a relatively elderly design that was originally produced by McDonnell Douglas; Boeing acquired the company in 1997. Although the last MD-11 came off the production line in 2001, Boeing has continued providing parts and service support.
After the Kentucky disaster, the NTSB issued a preliminary report that highlighted cracks in the engine attachment mechanism. The latest update describes fractures due to evidence of fatigue in a critical bearing as well as the mounting it is meant to sit in.
The report notes that Boeing had previously found failures of the same part on four occasions, affecting three different aircraft. In 2011, the company sent a service letter to operators warning them of its findings, recommending visual inspections every five years.
Tim Atkinson, a former air accident investigator, stated, The structure concerned is not decorative; it's an essential part of the mechanism that attaches the engine to the wing, highlighting the gravity of the oversight.
Boeing has faced scrutiny in the past regarding its internal processes and quality control, particularly following the 737 Max incidents that resulted in 346 fatalities.
In a statement, Boeing expressed support for the investigation and extended condolences to those affected by the crash. The NTSB's investigation remains ongoing, with no firm conclusions yet about the cause of the accident.
