WASHINGTON — Boeing CEO Dave Calhoun was hammered by a Senate panel on Tuesday over the company’s safety and quality lapses, a host of whistleblower allegations about company corner-cutting and retaliation, and his own pay package.

Calhoun, who said in March that he will step down by year’s end, defended the plane-maker’s actions to try to improve manufacturing quality and to fix its tarnished safety reputation in the wake of a midair door-panel blowout on an Alaska Airlines flight in January.

The company has still not named a replacement for Calhoun, who took over after its previous leader was ousted for the handling of two fatal Boeing crashes.

“Much has been said about Boeing’s culture. We’ve heard those concerns loud and clear. Our culture is far from perfect, but we are taking action and making progress,” Calhoun told the subcommittee.

Hours before the hearing the Senate subcommittee released whistleblower claims on Tuesday from Sam Mohawk, a quality-assurance investigator at Boeing, alleging the company lost track of parts that were damaged or not up to specification and that “those parts are likely being installed on airplanes.” The parts Mohawk flagged were in Boeing’s Renton, Washington, plant, where the company makes its best-selling 737 Max.

Mohawk said he was retaliated against and that he was told by supervisors to hide evidence from the Federal Aviation Administration, according to a memo shared by the committee on Tuesday. Dozens of important parts were stored outside during an FAA inspection, including 42 rudders as well as winglets and stabilizers, Mohawk alleged in claims with the Occupational Safety and Health Administration, the memo said.

Boeing issued a written warning against Mohawk, saying he engaged in “unacceptable/disruptive behavior or communication,” according to Mohawk’s complaint, which the subcommittee also made public. It said he could be “discharged” if the behavior continued. Mohawk’s also alleged the company reduced staffing during his shift making it difficult to complete tasks.

A Boeing spokeswoman said the company received the claims Monday night and that staff are reviewing them.

“We continuously encourage employees to report all concerns as our priority is to ensure the safety of our airplanes and the flying public,” she said.

The FAA said it has seen an increase in the number of reports from Boeing staff since the door-plug blowout in January.

“We thoroughly investigate every report, including allegations uncovered in the Senate’s work,” the agency said Tuesday. The FAA declined to comment on the specifics of the latest allegations.

Mohawk is not testifying before the Senate subcommittee’s hearing.

The hearing and new whistleblower claims are further complicating matters for Boeing. The company already faces potential U.S. prosecution after the Justice Department said last month that the plane-maker violated a 2021 settlement tied to 737 Max crashes in 2018 and 2019 that claimed 346 lives. A flight-control system Boeing included on the Max, the latest generation of a jet that has flown since the late 1960s, was implicated in the crashes.

The FAA had already halted Boeing’s ability to increase production of the Max, its bestselling plane. Whitaker last month said it would likely be several months before lifting that restriction.