On Tuesday, the Federal Aviation Administration proposed a fine of $435,000 against United Airlines. The FAA alleges that the air carrier operated an aircraft that it says was “not in airworthy condition.”

During June of 2014, mechanics at United Airlines replaced the pressure switch on a fuel pump on one of the airline’s Boeing 747s. However, the federal agency claims that United did not finish the required inspection for that repair prior to the aircraft being used again to carry passengers.

United in turn flew the airplane on 23 international and domestic passenger flights prior to the inspection be performed by their personnel says the federal aviation agency.

The aircraft might have made two additional flights even after the airline had been notified by the FAA relative to the problem, said the FAA in documents released.

Chief of the FAA Michael Huerta said that maintaining the highest safety levels depends upon the operators of aircraft to closely follow every applicable rule and regulation. Huerta added that failing to follow the rules and regulations can lead to unsafe flying conditions for passengers and crew.

United, through a prepared statement, provided an account that was slightly different about what it says happened.

United spokesperson Charles Hobart through a prepared statement said the airline had taken immediate action after it had identified the problem and were working closely with members of the federal agency in their ongoing review.

The FAA announced that United has requested a meeting with the federal agency to talk about the case.

This year has not been kind to United. The U.S. based airline had been hit hard with a number of issues that resulted in bad press, with the biggest coming after one of its passengers had been violently dragged from one of its flights during April.

The passenger had refused to voluntarily leave the plane then would not leave after being told to, due to the plane being overbooked. Video of the incident went viral across multiple social media sites including Facebook, Twitter and Instagram amongst others.

Since the incident took place, United has settled with the passenger who was identified as Dr. David Dao. The amount of the settlement was not released.

Incidents of a smaller proportion, like a rabbit that was 3 feet in length found dead following a flight on United, have hurt the public image of the airline.