The Federal Aviation Administration is reportedly investigating how counterfeit titanium ended up in aircraft for both Boeing and Airbus.

The New York Times broke the story this week of titanium with counterfeit documentation showing up in Boeing and Airbus jets, thanks to Boeing uncovering the issue and reporting it to the FAA.

“Boeing reported a voluntary disclosure to the FAA regarding procurement of material through a distributor who may have falsified or provided incorrect records,” an FAA statement said. “Boeing issued a bulletin outlining ways suppliers should remain alert to the potential of falsified records.”

The issue involved fuselages supplied by Spirit AeroSystems to Boeing, as well as wings supplied by the company to Airbus. The issue was first discovered when small corrosion holes were observed in the material.

To be clear, no on is saying the material in question is not titanium, only that the documentation used to sell it and verify it met the necessary requirements was forged.

The Times says Spirit is working to understand the scope of the problem, including whether the material in question meets structural requirements despite the counterfeit documentation, and whether the material will hold up for the life the jets it has been used in. If not, a costly parts replacement program will no doubt be the only way to salvage the aircraft.

“This is about documents that have been falsified, forged and counterfeited,” Joe Buccino, a Spirit spokesperson, told the Times. “Once we realized the counterfeit titanium made its way into the supply chain, we immediately contained all suspected parts to determine the scope of the issues.”

Both Boeing and Airbus say the material has been tested and meets the necessary spec.

“This industrywide issue affects some shipments of titanium received by a limited set of suppliers, and tests performed to date have indicated that the correct titanium alloy was used,” Boeing said in a statement. “To ensure compliance, we are removing any affected parts on airplanes prior to delivery. Our analysis shows the in-service fleet can continue to fly safely.”

“Numerous tests have been performed on parts coming from the same source of supply,” an Airbus spokesperson said in a statement, adding, “The safety and quality of our aircraft are our most important priorities, and we are working in close collaboration with our supplier.”