WASHINGTON (AP) — The Federal Aviation Administration said Monday it is proposing a $12 million civil fine against Southwest Airlines for failing to comply with safety regulations related to repairs on Boeing 737 jetliners.

It is the second-largest fine the agency has proposed against an airline. The largest proposed fine was against American Airlines for $24.2 million in August 2010. That one was ultimately settled for $24.9 million as part of American’s bankruptcy proceedings, although the final settlement included other safety violations not part of the original proposal.