In a statement, Boeing said the "nonconforming batch of slat track assemblies" were put on both Next-Generation 737s as well as 737 Max jets. The Max has been grounded since March, after a flawed flight control feature contributed to two crashes in five months, killing 346 people in Ethiopia and off the coast of Indonesia.
"We are working closely with our customers to take the appropriate corrective actions," the company statement said. A Boeing spokesman said he could not immediately provide the number of Max jets affected, but the company said Boeing "will ensure that all inspections and any necessary part replacements are performed on all 737 MAXs before they return to service."
Boeing said it has "not been informed of any in-service issues related to the slat tracks themselves."
The FAA said Spirit AeroSystems, Inc. supplied the slat tracks to Boeing. Spirit contracted with Kencoa Aerospace, LLC to provide the tracks. Kencoa, in turn, contracted with Southwest United Industries, Inc. to perform a metal plating process that was associated with the weakening of the wing parts, according to the FAA.
Representatives for the three suppliers did not immediately respond to requests for comment on Friday.
In 2015, Boeing agreed to pay a $12 million penalty as part of a settlement agreement with the FAA. The FAA said safety lapses with Boeing planes were repeatedly identified, and the company would agree to fix them but then fail to do so.
As part of that agreement, Boeing agreed to make significant changes in its internal safety systems and practices for "ensuring compliance" with regulations, and it remains subject to the terms of that agreement through Dec. 31, 2020.
In the case of the slat tracks, the FAA on Friday gave Boeing 30 days to "submit the suggested amount in settlement" or provide additional information.
Asked if the company planned to pay, a Boeing spokesman, Chaz Bickers, said, "We'll review the penalty."