FAA said it has proposed a $275,000 civil penalty against New York-based Atlas Airlines for allegedly operating a Boeing 747 after performing improper maintenance on the aircraft.

In a statement, FAA said it “alleges that Atlas maintenance workers improperly repaired the plane’s landing gear after it would not retract on departure from Sydney, Australia. Atlas repaired the gear using the wrong part, and maintenance workers had to install the component upside down to get it to fit.”

FAA alleges Atlas operated the aircraft on 24 cargo flights over a 10-day period after improperly repairing the landing gear.

“The aircraft was not in an airworthy condition during those flights,” the agency said in a statement.

An Atlas Air spokesperson told: “We have reviewed the FAA’s allegations in this case, which stem from an event that occurred and was addressed nearly five years ago. Atlas intends to vigorously defend itself. To that end, Atlas has requested an informal conference with the FAA and we look forward to resolving this matter with it. Our record clearly demonstrates we are committed to the highest levels of aircraft maintenance and safety. We take our responsibility to operate aircraft very seriously.”

FAA confirmed Atlas Air has been in communication with the agency.