“Josh’s passing is a loss to the aviation community and the flying public,” Brian Knowles, a lawyer who represented Dean as well as the other whistleblower, John Barnett, who died in March, tells TIME. “He possessed tremendous courage to stand up for what he felt was true and right and raised quality and safety issues.”

Airline parts manufacturer Spirit AeroSystems has asked a U.S. judge to block a probe by Texas Attorney General Ken Paxton, calling the state's demand for internal documents and other information unreasonable and unlawful.

A former Spirit AeroSystems quality auditor and engineer who had become a whistleblower against the company, died Tuesday at the age of 44. Joshua Dean, a Wichita-area native, was a witness in two lawsuits. In his testimony, he alleged the leadership — from managers to the president — ignored manufacturing issues with the Boeing 737 Max.