Barnett was involved in a whistleblower lawsuit against Boeing, alleging serious safety concerns at the North Charleston plant, where he managed quality for the 787 Dreamliner production.
A former Boeing staffer who once raised concerns about the company's production standards has been found dead in the US.
John Barnett, 62, was found dead in his truck in a hotel parking lot in South Carolina, cops 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 investigation.
Barnett's death came during a break in depositions in a whistleblower retaliation suit, where he alleged 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.