WASHINGTON >> Republican U.S. Senator Chuck Grassley said today he is launching a new congressional oversight inquiry into the Federal Aviation Administration and Boeing after a January mid-air emergency involving a 737 MAX 9.

The probe is the latest in a series of investigations by lawmakers since a door panel blew out during a Jan. 5 flight on a new Alaska Airlines MAX 9, forcing pilots to make an emergency landing while passengers were exposed to a gaping hole 16,000 feet above the ground.

Grassley, who first probed Boeing safety actions in the 1990s, said Boeing and the FAA “must explain how this happened and what is being done to ensure that it does not place the lives of Americans at risk again.”

He asked the FAA and Boeing to answer a total of 38 questions “requesting records of safety procedures, regulatory requirements, corrective actions (and) whistleblower protections.”

An FAA audit found serious issues at Boeing, while the FAA has capped the planemaker’s production of its best-selling 737 MAX.

The FAA said it would “respond directly to the senator.” Boeing said it “will continue to be responsive and transparent with Congress.”

Outgoing Boeing CEO Dave Calhoun will testify before the U.S. Senate Permanent Subcommittee on Investigations on Tuesday after a series of incidents raised concerns about safety and quality,

The committee’s chair, Democratic Senator Richard Blumenthal said earlier this month after two fatal crashes in 2018 and 2019 that killed 346 people, “Boeing made a promise to overhaul its safety practices and culture. That promise proved empty, and the American people deserve an explanation.”

Senate Commerce Committee chair Maria Cantwell said Thursday she could call Calhoun to appear at a future hearing. The top Republican on the panel, Senator Ted Cruz, said he was disappointed Calhoun was not appearing before Commerce, which has jurisdiction over aviation safety.

Calhoun has said he will leave by the end of the year as part of a broader management shakeup, as Boeing faces multiple government investigations and pressure from investors and airlines to find a new CEO.

During a hearing in April before Blumenthal’s committee, a Boeing engineer testified the company took dangerous manufacturing shortcuts with certain planes and sidelined him when he raised safety concerns, claims the company disputes.

Boeing faces an ongoing Justice Department investigation into the door plug blowout.