The Federal Aviation Administration said it would investigate allegations that titanium had entered the supply chain via falsified documents.

The Federal Aviation Administration said it would investigate allegations that titanium had entered the supply chain via falsified documents.

Boeing and Airbus, the two biggest commercial airline makers, may have used titanium sold using fake documents, according to evidence from a supplier that has triggered a Federal Aviation Administration investigation.

The FAA said in a statement to NBC News on Friday morning it would look into allegations from Spirit Aerosystems that the two aviation giants used titanium in their planes that came with paperwork verifying its authenticity that could have been falsified.

The news adds to a troubled period for Boeing, which is the subject of ongoing federal investigations for alleged safety problems. But the news also brings its fierce rival, France-headquartered Airbus, into the wider scrutiny the aviation industry is facing.