WASHINGTON, D.C. — The Federal Aviation Administration (FAA) seeks to fine Southwest Airlines a record $10.2 million for failing to inspect 46 of its Boeing 737 airplanes for fuselage fatigue cracking. The air carrier subsequetly found that six of the jetliners had fatigue cracks.

“The FAA is taking action against Southwest Airlines for a failing to follow rules that are designed to protect passengers and crew,” said FAA Associate Administrator for Aviation Safety Nicholas A. Sabatini. “We expect the airline industry to fully comply with all FAA directives and take corrective action.”

From June 18, 2006 to March 14, 2007, the FAA alleges that Southwest Airlines operated 46 Boeing 737 airplanes on 59,791 flights while failing to comply with a September 8, 2004 FAA Airworthiness Directive (AD) that required repetitive inspections of certain fuselage areas to detect fatigue cracking.

The FAA alleges that after Southwest Airlines discovered that it had failed to accomplish the required repetitive inspections, it continued to operate those same 46 airplanes on an additional 1,451 flights.

It is reported that the U.S. Department of Transportation and a congressional panel are inquiring as to why the FAA did not ground the jetliners after learning of the missed inspections.

The U.S. aviation agency says the amount of the civil penalty reflects the serious nature of those deliberate violations.

Southwest said it had disclosed the missed inspections to the FAA in March 2007. “We believed at that point that the matter was closed,” a company spokesman said. Southwest said in a statement that safety was never compromised.

ADs are issued by the FAA to correct an unsafe condition in an aviation product. In this case, the FAA’s AD mandated repetitive external detailed and eddy-current inspections at intervals of no more than 4,500 flight cycles to detect fatigue cracking in areas of the fuselage skin on some Boeing 737 models.

Southwest Airlines has 30 days from receipt of the FAA’s civil penalty letter to respond to the agency.