US air safety authorities are investigating whether embattled aviation giant Boeing completed required inspections on its 787 aircraft and whether employees falsified records, officials said Monday.

The issue centers on whether Boeing undertook required inspections to "confirm adequate bonding and grounding where the wings join the fuselage on certain 787 Dreamliner airplanes," the Federal Aviation Administration said in an email.

The FAA said it opened the investigation after Boeing notified it that the company may not have completed required inspections, which are needed to ensure a safe and functional electrical flow between aircraft components.

"The FAA is investigating whether Boeing completed the inspections and whether company employees may have falsified aircraft records," the agency said. "At the same time, Boeing is reinspecting all 787 airplanes still within the production system and must also create a plan to address the in-service fleet."

The issue surfaced after a Boeing employee observed an "irregularity" and raised the issue with a supervisor who elevated it further.

"We quickly reviewed the matter and learned that several people had been violating company policies by not performing a required test, but recording the work as having been completed," Scott Stocker, head of the Boeing 787 program, said in an email to staff.

"We promptly informed our regulator about what we learned and are taking swift and serious corrective action with multiple teammates," said Stocker, adding that engineering staff determined that the issues does not pose an immediate safety of flight risk.

The probe adds to the litany of issues facing Boeing in the aftermath of a near-catastrophic Alaska Airlines flight in January in which a panel on the fuselage blew out.

The FAA has given the company three months to present a plan to address "systemic quality-control issues."

Boeing's management of the 787 came under question at an April 17 Senate hearing at which a company whistleblower testified that he was retaliated against after raising questions about manufacturing processes on the 787 that he believed threaten aircraft safety.

An audit by an FAA advisory panel released in February pointed to significant shortcomings in Boeing's safety culture, describing a "disconnect" between senior company management and other Boeing employees and skepticism that safety complaints by workers would not result in retaliation.

In his message to employees, Stocker praised the employee for coming up, saying the company "will use this moment to celebrate him, and to remind us all about the kind of behavior we will and will not accept as a team."

- Board under scrutiny -

Safety experts have said the problems at Boeing suggest significant safety culture defects that will not be turned around quickly.

Industry watchers are waiting for more clues about future leadership of Boeing after Chief Executive Dave Calhoun said he will step down at the end of the year.

Glass Lewis, the proxy advisory firm, last week urged investors to vote against Calhoun's reelection to the board and two other board members who lead the audit and aerospace safety committees.

The move is needed "to strongly signal dissatisfaction with the company's oversight of its safety culture and its efforts to transform said culture, which, in our view, have not progressed quickly enough to a level that sufficiently mitigates shareholder concern when safety incidents occur, as evidenced by the Alaska accident," Glass Lewis said in a note.