The US Federal Aviation Administration (FAA) says it is planning to issue a USD325,000 civil penalty against Southwest Airlines (WN, Dallas Love Field) for allegedly operating a B737 that was not in compliance with US Federal Aviation Regulations (FAR).

The FAA says it undertook an ageing aircraft inspection of the jet at San Salvador International, in July last year during which time it discovered that Southwest had improperly recorded a temporary repair to an approximately nine-inch crease in the aluminium skin of the aircraft’s rear cargo door as a permanent repair.

"The inspector discovered that this fuselage damage had first been reported in Southwest Airlines’ maintenance records on May 2, 2002, which is when the airline made the temporary repair. The airline was required to inspect the temporary repair every 4,000 flights and complete a permanent repair within 24,000 flights," the FAA said.

The FAA alleges the LCC operated the aircraft on 24,831 flights without performing the periodic inspections required for the temporary repair. The agency further alleges the aircraft was operated on 4,831 flights beyond the flight threshold required for it to carry out a permanent repair. The final repair was eventually completed on July 24, 2014.

The FAA says it has contacted Southwest over the incident.

Since November of last year and inclusive of this claim, the FAA has proposed a total USD13.9 million in fines against the Texan budget carrier for violating FARs relating to tarmac delays as well as aircraft maintenance.