A former Boeing staffer who once raised concerns about the company's production standards has been found dead in the US, Ednews informs referring to The Daily Mail.

John Barnett, 62, was found dead in his truck in a hotel parking lot in South Carolina, his lawyer said Monday - seven years after he retired following a 32-year career.

The ex-quality manager at Boeing's North Charleston plant died from a 'self-inflicted' wound, cops in Charleston said, adding that they were still investigating.

Barnett's death came during a break in depositions in a whistleblower retaliation suit, where he alleged that under-pressure workers were deliberately fitting sub-standard parts to aircraft on the assembly line.

He said that in some cases, second-rate parts were literally removed from scrap bins, before being fitted to planes that were being built to prevent delays. A 2017 review by the FAA upheld some of his concerns, requiring Boeing to take action.

He had just given a deposition to Boeing's lawyers for the case this past week, his attorney Brian Knowles said.

In an email, he called his client's death 'tragic'.

'Today is a tragic day,' Knowles wrote, revealing that Barnett 'was supposed to do day three of his deposition here in Charleston on his AIR21 case [on Saturday],' referring to a federal law that provides whistleblowers protection in the aviation industry.

Boeing also responded to the former worker's death in their own statement as news spread on Monday, saying it was 'saddened by Mr. Barnett's passing.'

The statement did not address any aspects of the case, but brass ultimately added: 'Our thoughts are with his family and friends.'