The Federal Aviation Administration said Friday it plans to fine Boeing $5.4 million for installing substandard parts on the wings of 178 of its 737 Max jetliners, which have been grounded since two crashes linked to other systems on the planes.
The proposed civil penalty follows an FAA announcement last month that it would fine Boeing more than $3.9 million for installing the same parts on other versions of the 737.
At issue are tracks that guide the movement of control surfaces called slates on the front of the wings on 737s — both the Max and the previous model of 737, called the NG. The slats give the planes extra lift during takeoffs and landings.
The FAA said that poor oversight of suppliers led Boeing to install tracks that could become brittle and weak because of mistakes during manufacturing.
The FAA said the faulty tracks were made in mid-2018 by Southwest United Industries, which supplied them to Boeing contractor Spirit AeroSystems. Spirit later delivered them to Boeing.
Chicago-based Boeing has 30 days to respond to the FAA.