US investigators say Boeing had earlier knowledge of a serious structural weakness linked to a UPS cargo plane crash that killed 15 people in Kentucky.
The aircraft, an MD 11F freighter operated by UPS, crashed in November near Louisville as it attempted to take off. One of its engines broke away from the wing moments after the plane lifted from the runway. The aircraft then lost control and slammed into an industrial area.
Three crew members and twelve people on the ground died.
Known cracks in a critical engine part
According to a new update from the US National Transportation Safety Board, the engine mounting system showed cracks caused by long term stress. Investigators say similar failures had already been found on other aircraft years earlier.
Boeing, which took over the MD 11 program after acquiring McDonnell Douglas in 1997, had identified the same defect as far back as 2011. At the time, the company decided the issue would not affect flight safety.
Inspection advice but no mandatory fix
The safety board says Boeing recorded at least four failures of the same engine mounting component across three aircraft. After those findings, the company sent operators a service letter to share the information.
The letter advised visual inspections every five years and pointed operators to updates in the maintenance manual. It also mentioned a redesigned bearing assembly that could be installed, but did not require airlines to do so.
Service letters are guidance only and do not carry legal force.
Experts raise serious concerns
Aviation safety consultant Tim Atkinson, a former accident investigator, said the update raises troubling questions.
He explained that the failed structure plays a key role in securing the engine and handling forces such as thrust and drag. In his view, it is hard to understand how such a failure could be judged as having no safety impact.
Broader scrutiny of Boeing safety culture
Boeing has faced growing criticism over its internal safety processes in recent years.
Concerns have included software problems on the 737 Max that contributed to two fatal crashes in 2018 and 2019, killing 346 people. More recently, manufacturing quality came under scrutiny after a door panel detached from a new 737 Max shortly after takeoff in early 2024.
