Boeing Co (BA  ) and Airbus SE (EADSY  ) shares are trading lower on Friday.

The U.S. Federal Aviation Administration (FAA) is currently investigating the possible use of false documentation to verify titanium components in some of Boeing's and Airbus's aircraft, discoveries that could affect the integrity of critical aerospace materials.

The inquiry extends to both major aircraft manufacturers and focuses on the authenticity of titanium, a vital metal used throughout the aerospace industry, Reuters reports.

The issue was discovered by a vendor, who discovered corrosion holes in titanium parts, prompting the FAA to investigate immediately.

Boeing has voluntarily disclosed the procurement of potentially compromised material sourced from a distributor suspected of falsifying or providing incorrect records.

In response to these findings, Boeing has issued a bulletin to its suppliers advising them to remain vigilant against falsified records.

Spirit AeroSystems Holdings Inc (SPR  ), a key supplier for both Boeing and Airbus, acknowledged that the problematic titanium had been introduced into the supply chain through counterfeit documentation, leading to the quarantine and removal of all suspect parts from production lines.

Spirit AeroSystems has conducted over 1,000 tests to verify the mechanical and metallurgical properties of the affected materials, ensuring they meet safety standards for continued airworthiness.

The investigation is set against the backdrop of an increasing demand for new aircraft driven by a resurgence in post-pandemic travel.

However, ongoing supply chain challenges and component shortages are complicating efforts by manufacturers to ramp up production.

Airbus is struggling with parts and labor shortages, which are impacting its jet production timeline and could affect its goal of increasing output to 75 planes monthly by 2026.

The investigation comes even as the head of the Federal Aviation Administration admitted on Thursday to insufficient oversight of Boeing following a mid-air emergency involving Alaska Air Group, Inc (ALK  ).

Boeing stock has lost 16% in the last 12 months. Investors can gain exposure to the stock via IShares U.S. Aerospace & Defense ETF (ITA  ) and Invesco Aerospace & Defense ETF (PPA  ).

Price Action: BA shares are trading lower by 1.66% at $177.66 at the last check on Friday. EADSY shares are trading lower by 2.32% at $39.24 at last check Friday.