The Federal Aviation Administration (FAA) said on Friday it was seeking tofineBoeingCo$5.4million(£4.14million), alleging it failed to prevent the installation ofdefectivepartson737MAXaeroplanes.
The FAA allegedBoeing"failed to adequately oversee its suppliers to ensure they complied with the company's quality assurance system, Boeingknowingly submitted aircraft for final FAA airworthiness certification after determining that thepartscould not be used due to a failed strength test."
The FAA proposed a $3.9millioncivil penalty againstBoeingfor the same issue in December involving 133737NG aeroplanes, which is the prior generation of the737.
The737MAXhas been grounded since March after two fatal crashes killed 346 people.Boeing's safety record on a number of issueshave come under scrutiny from lawmakers and the FAA.
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Thepartsissue is completely unrelated to the crashes,Boeingsaid.
The FAA disclosed in June that about 300 NG and737MAXaeroplanescould contain improperly manufacturedpartsand said it would require thesepartsto be quickly replaced.
Thepartsat issue are tracks on the leading edge of the wings used to guide the movement of slats that provide additional lift during takeoff and landing, the FAA said. The issue could result in a slat striking an aeroplane, potentially resulting in injury to passengers or preventing a safe landing.
The FAA saidBoeing's oversight failure "resulted in the installation of slat tracks that were weakened by a condition known as hydrogen embrittlement that occurred during cadmium-titanium plating."
Boeingsaid Friday it was aware of the proposed penalty and said it has not seen any in-service issueswith theparts, which are covered by a service bulletin and airworthiness directive.
"We will ensure that all inspections and any necessary part replacements are performed on all737MAXs before they return to service. We have not been informed of any in-service issuesrelated to the slat tracks themselves,"Boeingsaid.