American Airlines today announced grounding its MD-80 fleet for the second time in two weeks to re-inspect the aircraft for airworthiness compliance.

The groundings, which will cancel up to 500 flights today, were needed after US FAA officials questioned the adequacy of the first round of inspections, the airline says.

More flights could be cancelled Thursday.

“We will continue to work in good faith until we satisfy all of the technical issues related to this airworthiness directive," says Gerard Arpey, Chairman and CEO of American Airlines.

The carrier first inspected the MD-80 fleet on 26 March, but those checks proved insufficient.

The FAA is concerned that about “the manner in which American followed the engineering change order (ECO) that had been written for the airworthiness directive related to the wiring in the MD-80s wheel wells.” the airline says.

“Specifically, some areas of concern included the spacing of the ties on the wiring bundle and the direction in which the retention clips and lacing cords were facing,” an American statement adds.

American says it will remove any MD-80 from service that does not comply with the technical specifications of the airworthiness directive.

In addition, American has received FAA approval to use an “an alternative method of compliance (AMOC) for this airworthiness directive that has already been applied to the MD-80 fleet of other carriers,” the airline says.