Here’s the thing about being fined by the U.S. government –– they won’t stop until you pay them. At least that appears to be the case with Southwest Airlines, which is being sued by the Justice Department for failure to pay a $12 million civil penalty levied by the Federal Aviation Administration earlier this year.

Reuters reports that the Justice Dept. filed the suit in a district court in Washington state, seeking to enforce the civil penalty imposed on the airline after an investigation into repairs of the company’s planes.

A Southwest spokesperson told the New York Times on Monday that the company would “dispute the FAA’s allegations and look forward to the opportunity to vigorously defend Southwest’s record in a court of law.”

Back in July, the FAA announced the fine after investigators found three separate incidents in which Southwest and its hired contractor improperly repaired aircraft.

The incidents began in 2006 when Southwest carried out “extreme makeover” alterations to eliminate possible cracking of the aluminum skin on 44 Boeing 737 jetliners.

According to the FAA’s investigation, the contractor hired by Southwest – Aviation Technical Services –failed to follow required procedures regarding the placement of the airplanes on jacks and stabilizing them while replacing the fuselage skins on the aircraft. By not following the proper protocol, the airframe could shift and lead to problems with the new skin.

Despite begin notified of the issue, Southwest returned the jetliners to service and operated them when they were not in compliance with federal aviation regulations, the FAA said in a news release at the time.

However, the agency later approved the repairs after the airline provided proper documentation that the repairs met safety standards.

The second incident occurred when the contractor applied sealant beneath the new skin panels but failed to install fasteners to all the rivet holes while the sealant was effective. The omission could have resulted in gaps between the skin and the plane’s surface which could let moisture inside leading to corrosion.

In the final case, the FAA alleges that Southwest failed to properly install a ground wire on water drain masts on two of its aircraft as required by the FAA Airworthiness Directive regarding lightning strikes. The airplanes were each operated on more than 20 passenger flights after Southwest Airlines became aware of the discrepancies but before the airline corrected the problem.

U.S. sues Southwest Airlines to recover maintenance fine [Reuters]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.