The Federal Aviation Administration proposed a $12 million fine against Southwest Airlines for allegedly not complying with safety regulations during Boeing 737 jetliner repairs.
The proposed fine is the second largest in FAA history, the Associated Press reports. In 2010, the FAA proposed a $24.2 million fine against American Airlines, which later settled for $24.9 million.
The agency says that Southwest's contractor, under Southwest supervision, did not properly fasten aircraft skins and replace fuselages, among other violations, while updating 44 planes in 2006 to prevent cracking on the aluminum exteriors. The agency also claims the Dallas-based air carrier flew those planes in 2009 despite notice from the FAA about the lack of safety compliance.
A spokesperson for Southwest said the company would respond to the agency's claims in accordance with FAA procedure guidelines. The airline also said it "fully resolved the repair issues some time ago" and that "none of the items raised in the FAA letter affect" planes currently in operation.