Southwest Airlines has agreed to pay a $2.8 million civil penalty to settle a lawsuit brought by the US government over its failure to conduct maintenance work properly.
The airline also agreed to beef up oversight over third party contractors that perform maintenance on its aircraft.
The airline could pay up to $5.5 million if it fails to make good on its promise.
The lawsuit brought by the Federal Aviation Administration sought $12 million in total related to maintenance violations in three separate cases.
Two of these were carried out by contractor Aviation Technical Services (ATS) under the supervision of Southwest.
The FAA said ATS technicians failed to apply sealant beneath fuselage skin panels correctly and did not secure the airplanes in place in the correct manner while the repair work was being carried out.
In a third case, Southwest made incorrect repairs to fluid-draining systems.
"Safety depends on compliance with our regulations," said federal aviation administrator Michael Huerta in a statement.
"This agreement provides strong incentives for Southwest to take specific steps to address the compliance problems that the FAA investigations uncovered."
In response, Southwest said in a statement: "The settlement allows us to move forward and focus on our current and future priorities. The safety of our aircraft remains our top priority, and to that end, we remain committed to meeting or exceeding all applicable FAA safety regulations."
