The Federal Aviation Administration said Friday it plans to fine$5.4 million for installing substandard parts on the wings of 178 of its , which have been grounded were 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.
Boeing said it has no reports of the parts causing a problem during flights. The company said it is working with airlines to make corrections, and will make sure all inspections and any needed part replacements will be done before the 737 Max planes return to service.
The FAA proposed fine covers tracks that guide the movement of control surfaces, called slats, 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 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 given cadmium-titanium plating in mid-2018 by Southwest United Industries, which supplied the finished tracks to Boeing contractor Spirit AeroSystems, which delivered them to Boeing.
Chicago-based Boeing has 30 days to respond to the FAA.
The administration also announced plans Friday to seek $3.9 million from Southwest Airlines for failing to properly calculate the weight of planes and make sure loads were balanced before more than 21,500 flights in 2018.
The FAA said Friday the violations occurred on 44 of Southwest's planes over more than three months.
Weight is used to determine the maximum number of passengers on a plane and how much fuel it should carry, and cargo must be balanced to avoid having too much weight in the front or back, which can affect the way a plane flies.
Southwest has 30 days to respond to the FAA's proposed civil penalty. Airlines often try to negotiate down the size of FAA fines.