A former Boeing supplier quality auditor, Joshua Dean, died at the age of 45 due to a sudden and fast-spreading infection.
His death comes two months after another Boeing whistleblower, John Barnett, reportedly died by suicide.
Dean had been ill for just over two weeks with breathing difficulties and received aggressive medical intervention, including an ECMO machine, but ultimately passed away.
The cause of Dean's infection remains unclear.
Dean, a former Spirit AeroSystems employee, raised concerns about potential manufacturing flaws in Boeing's 737 MAX planes, including improperly drilled holes in the aft pressure bulkhead.
After documenting his observations, he was fired in April 2023, which he believed was retaliation.
The timing of his death is similar to that of Barnett, who died by suicide during a lawsuit alleging retaliation for exposing safety concerns with the 787 Dreamliner.
Last month, former Boeing engineer Sam Salehpour testified before lawmakers about a culture within Boeing that prioritizes pushing flawed components, disregarding safety risks.
A veteran Boeing engineer named Salehpour with 17 years of experience raised safety concerns about the 787 Dreamliner and 777 aircraft.
He faced repercussions and became a whistleblower.
Boeing acknowledged the existence of imperfections but assured ongoing improvements.
However, Boeing disputed Salehpour's claims about the Dreamliner's safety, stating that extensive testing did not show any signs of fatigue.