The U.S. Federal Aviation Administration is investigating falsified documents that were used to verify the authenticity of titanium used in some recently manufactured Boeing and Airbus jets, the New York Times reported on Friday.

The documents are also being investigated by Spirit AeroSystems, which supplies fuselages for Boeing and wings for Airbus, according to the report.

Titanium, an important component in the aerospace supply chain, is used to make landing gears, blades and turbine discs for aircraft.

The FAA is investigating the scope of the problem and trying to determine the short-and long-term safety implications to planes that were equipped with those parts, NYT reported, citing a statement from the regulator.

The investigation comes after a parts supplier found small holes in the material – used in manufacturing of jets – from corrosion, the report added.

Aircraft manufacturers are facing strong demand for new planes due to a surge in post-pandemic travel. However, supply chain issues and component shortages are limiting their ability to meet this demand.

Last year, jet engine manufacturer CFM International disclosed that thousands of its engine components might have been sold with falsified documentation by a British distributor.

The discovery had prompted airlines to change parts on a handful of planes.

The FAA, Boeing, Airbus and Spirit did not immediately respond to Reuters requests for comments.

Boeing and Spirit shares were down about 1% each in premarket trading.

(Reporting by Shivansh Tiwary in Bengaluru; Editing by Nivedita Bhattacharjee and Shailesh Kuber)