The Department of Transportation’s inspector general has cited several issues with maintenance at American Airlines that resulted in flights by unairworthy aircraft.

The report, released Sunday, notes the IG’s office is critical of the FAA’s relationship with the airline, noting the agency lacks sufficient oversight to determine whether the airline appropriately identifies, assesses, and mitigates aircraft maintenance risks.

“FAA’s oversight controls are also not effective for evaluating if American Airlines’ (safety management system) sufficiently assesses and mitigates risk,” the report says. “The FAA requires American Airlines to use its SMS to determine the level of risk associated with maintenance non-compliances.”

Among the issues documented was a jet that flew passengers for 877 days with a broken emergency evacuation slide. In another instance, a jet flew for 1,002 hours with missing engine bushings and improperly installed struts holding the engines in place.

The report found “that FAA inspectors did not routinely or consistently evaluate whether the carrier adequately and effectively assessed and rated risks. This is in part because the FAA did not provide its inspectors with comprehensive training and tools for overseeing and evaluating the carrier’s SMS.”

The report also indicates that there were times when FAA inspectors prematurely closed out compliance actions before ensuring that the carrier completed them.

The report contains recommendations to improve American Airlines' safety compliance, adding that the FAA is working with the IG to develop training and tools for inspectors to prevent future issues.

American Airlines is one of the largest airlines in the world and has not experienced a fatal accident in nearly 20 years.

American defended its safety record in an emailed statement to The Associated Press.

“This has always been our approach: open, transparent communication and collaboration with our regulators and immediate action to remedy issues and ensure the continued safety of our airline and the industry,” an airline spokeswoman wrote. “We plan to work with the FAA to ensure we take positive action and continuously refine and improve our safety controls”