WASHINGTON (AP) — The government is proposing a $12 million civil fine against Southwest Airlines for failing to comply in three separate cases with safety regulations related to repairs on Boeing 737 jetliners.

The Federal Aviation Administration said Monday that beginning in 2006 Southwest made "extreme makeover" alterations to eliminate potential cracking of the aluminum skin on 44 jetliners.

The FAA said an investigation determined that Southwest's contractor, Aviation Technical Services Inc. of Everett, Washington, failed to follow proper procedures for replacing the fuselage as well as other work on the planes. The agency said all of the work was done under the supervision of Southwest Airlines.

The statement said Southwest returned the planes to service when they were not in compliance with regulations.

Southwest has 30 days to reply to the proposed fine.

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