The National Transportation Safety Board said in a report on Wednesday that a UPS cargo plane that crashed in Louisville, Ky., last year, killing 15, had a structural flaw that the manufacturer Boeing had previously concluded would not affect flight safety.
The N.T.S.B. has said that cracks in the assembly holding the left-side engine in place may have contributed to the November crash, though it has not officially cited a cause. The part had fractured in similar fashion on at least four other occasions, on three different airplanes, according to the report, which cited a service letter that Boeing issued in 2011 regarding the apparent flaw.
In the service letter, which manufacturers issue to flag safety concerns or other problems to aircraft owners, Boeing said that fractures “would not result in a safety of flight condition,” N.T.S.B. investigators wrote.
The plane that crashed was an MD-11F jet, made by McDonnell Douglas, a company that Boeing acquired in the 1990s. It was taking off from Louisville and bound for Hawaii on Nov. 4 when a fire ignited on its left engine shortly after takeoff.
The plane crashed into several buildings, including a petroleum recycling facility, on the outskirts of the Louisville Muhammad Ali International Airport. The three crew members on board and 11 people on the ground were killed in the crash; a 12th person on the ground died of injuries sustained during the episode.
In a statement, a Boeing representative said that the company supports the N.T.S.B.’s investigation and expressed condolences to the families of the victims. The company, one of the world’s largest airplane manufacturers, has been under pressure in recent years over concerns about its quality control. It did not address the report’s findings in its statement.
After the crash, Boeing recommended that all MD-11s be grounded while the N.T.S.B. conducted its investigation. UPS also announced that it would ground its fleet of MD-11s, and the Federal Aviation Administration issued a temporary ban on flying such planes, citing concerns that a similar engine detachment “could result in loss of continued safe flight and landing.”
In an initial report in November, N.T.S.B. investigators noted that parts of the bearing assembly connecting the left engine to the cargo plane’s wing had fractured and showed signs of “fatigue cracks” and “overstress failure.” According to the N.T.S.B.’s most recent report, Boeing had recommended in its service letter that the part be inspected every 60 months as part of a general visual inspection.
The N.T.S.B.’s preliminary report stated that UPS’s policy was to inspect the part as part of a general visual inspection every 72 months, and that it had last been scrutinized on Oct. 28, 2021 — about 49 months before the crash. The preliminary report also noted that the bearings had been lubricated about two weeks before the crash, on Oct. 18, 2025.
The preliminary report also stated that the lugs holding the part in place, which were also fractured, and other coupling devices, weren’t due for a special inspection for another few thousand takeoffs and landings.
Karoun Demirjian is a breaking news reporter for The Times.
The post Boeing Knew About Flaws in UPS Plane That Crashed in Louisville, N.T.S.B. Says appeared first on New York Times.
