Tens of thousands of passengers were upset Thursday when American and Delta Air Lines cancelled more flights to continue their inspections of wiring bundles on certain planes.

American cancelled 132 of its more than 2,000 flights that were scheduled for Thursday, spokesman Tim Wagner said, according to the Associated Press.

Delta expects around 275 cancellations to take place by Friday, affecting around 3 percent of its total flight schedule, informed spokesman Chris Kelly.

Apparently, American started the inspection following an audit of the carrier by a joint team of inspectors from the Federal Aviation Administration and the Fort Worth-based airline. The inspection aimed to check whether the spacing between the two bundles of wires in the plane’s auxiliary hydraulic system respected an FAA directive, as it was supposed to.

Wagner assured the travelers that the company expected nearly all planes to be ready for flight tomorrow.

"We expect all but a few to be back in service by tomorrow," he said, according to the Associated Press.

The spokesman for Delta said he did not know yet the number of passengers that had been affected by the cancellations.

As for American Airlines, it has been reported that more than 26,000 passengers had to find other means of transport after the company cancelled about 300 flights.

This isn’t the first time AMR Corp. has to cancel some of its flight because of the special maintenance audits carried out by the FAA. The agency proposed a $10.2 million fine against Southwest Airlines Co. on March 6 for flying 46 jets uninspected. Since then the nation’s airlines have gone through increased inspections.