Joshua Dean, a Boeing whistleblower who warned of manufacturing defects in the planemaker’s 737 Max, has died after a short illness, the second Boeing whistleblower to die this year.

Dean, 45, a former quality auditor at Boeing supplier Spirit AeroSystems, filed a complaint with the Federal Aviation Administration (FAA) alleging “serious and gross misconduct by senior quality management of the 737 production line” at Spirit.

In 2018 and 2019, two 737 Max planes were involved in fatal crashes, which killed 346 people. Dean was fired by Spirit last year, and filed a complaint with the Department of Labor alleging that his termination was in retaliation for raising safety concerns.

According to the Seattle Times, Dean was hospitalized after having trouble breathing. He was intubated and developed pneumonia and a serious infection before dying two weeks later.

“He passed away yesterday morning, and his absence will be deeply felt. We will always love you Josh,” Dean’s aunt, Carol Dean Parsons, said.

Dean was represented by the same law firm that represented Boeing whistleblower John “Mitch” Barnett. Barnett, 62, was found dead in March from what appeared to be a self-inflicted gunshot wound.

Barnett spent almost three decades at Boeing, and told the New York Times in 2019 that he had found “clusters or metal slivers” hanging over the wiring of flight controls that could have caused “catastrophic” damage if they had penetrated wires.

He alleged that management had ignored his complaints and moved him to another part of the plant.

Last month, another Boeing whistleblower, Sam Salehpour, told Congress there was “no safety culture” at Boeing, and alleged that employees who raised the alarm were “ignored, marginalized, threatened, sidelined and worse”. He said he feared “physical violence” after going public with his concerns.