The US has opened a new probe of troubled jet firm Boeing, after the company told air safety regulators that it might not have properly inspected its 787 Dreamliner planes.
The Federal Aviation Administration (FAA) said it would look into whether staff had falsified records.
It said Boeing was reinspecting all 787 jets still on the manufacturing line.
Boeing will be forced to develop an “action plan” to address concerns about planes already in service, it added.
Boeing did not comment.
Internally, it told staff that the “misconduct” had not created an “immediate safety of flight issue”, according to a message seen by the Wall Street Journal, which first reported the investigation.
Shares in the company fell more than 1% after the investigation was announced.
The FAA said that Boeing had come forward “voluntarily” last month to warn that it “may not have completed” inspections required to confirm electrical safeguards where the wings join the main body of the 787 Dreamliner, a large jet often used on international flights.
“The FAA is investigating whether Boeing completed the inspections and whether company employees may have falsified aircraft records,” it said.
“As the investigation continues, the FAA will take any necessary action – as always – to ensure the safety of the flying public.”
It is the latest problem to erupt at Boeing since January, when an unused emergency exit door plug blew off a new 737 Max 9 plane shortly after take-off in January, thrusting its manufacturing and safety processes into the spotlight.
The incident prompted the temporary grounding of dozens of planes and has forced the firm to drastically slow production, while sparking increased regulatory oversight, criminal investigation and other legal and financial troubles.
In March, chief executive Dave Calhoun said he would be stepping down by the end of the year, becoming the most high-profile person to exit the company in the wake of the incident.
Last month, Congress hosted a hearing featuring whistleblowers, including Sam Salehpour who testified that his concerns about the 787 were dismissed.
Boeing has said it is working to reform its corporate culture to encourage people who see problems to speak out, with a “more than 500% increase” in reports from employees since January.