Aircraft maintenance is critical for safe flights, and federal regulators continue to ground, inspect and re-inspect hundreds of planes in order to establish whether they comply with the safety demands. Hundreds of thousands of passengers have been affected by the inspection audits, which are scheduled to expand to all U.S. carriers.

The case of Southwest Airlines is well known by now: the planes grounded last month were found to have cracks, which was a clear sign that they have not been properly inspected. The federal regulators proposed a civil penalty against the company of $10.2 million, The Wall Street Journal reports. This will add up to the financial loses after being forced to cancel numerous flights.

Another carrier, American Airlines, is currently undergoing an inspection that forced them to cancel as much as 600 flights. The methods of the Federal Aviation Administration (FAA) are considered to be too harsh by some carriers, saying there was no need to cancel all those flights as part of the unprecedented inspection that is said to continue months from now.

While some agree with the FAA, others believe they are overreacting, saying flight safety has not been compromised so far. However, safety experts disagree, considering the inspection audits to be necessary for decreasing long-term risks.

American Airlines already had to apologize to over 200,000 passengers for canceling the flights, and although the flight schedule is expected to be back on track by Saturday night, the detailed inspection will probably cost them millions of dollars, as a representative of the company said.

The FAA motivated its actions by saying that although flights are still considered to be safe, it is their duty to ensure that the Southwest Airlines situation won’t repeat itself in other states.

American Airlines is currently facing a crisis situation, as most passengers who found their flights to be canceled will probably think twice before choosing the same carrier. FAA refused American Airlines’ proposal for planes to undergo inspection on a rolling basis, deciding to ground the entire fleet instead.