The panel that blew out of an Alaska Airlines jetliner this month was manufactured in Malaysia by Boeing’s leading supplier, the head of the agency investigating the incident said Wednesday.

Jennifer Homendy, chair of the National Transportation Safety Board, said her agency will look into how the part was produced by Spirit AeroSystems and installed on the plane. She made the comments to reporters in Washington after a closed-door briefing for senators.

A spokesman for Spirit AeroSystems confirmed that the plug was made in Malaysia and said the company is committed to cooperating with the NTSB.

Separately, officials said airlines have inspected 40 planes identical to the one involved in the accident. The Federal Aviation Administration said it will review information from those inspections of Boeing 737 Max 9 jets while it develops a maintenance process before letting the planes carry passengers again.

Boeing’s CEO spent the day visiting Spirit AeroSystems’ headquarters and factory in Wichita, Kansas, and vowed that the two companies will work together to “get better.”

In Washington, Homendy and FAA Administrator Mike Whitaker spent two hours briefing members of the Senate Commerce Committee. The officials indicated that their separate investigations of Boeing and the accident are in the early stages.

“Nothing was said about penalties or enforcement, but when there is an end result, I have no doubt but that there will be consequences,” said Sen. Jerry Moran, a Kansas Republican.

Moran said Whitaker indicated that the FAA is focusing “on the challenges that Boeing has faced over a longer period of time, of which this incident, this potential disaster, was only one component.”

During the briefing, “there was also interest in trying to make sure that the FAA is doing its job in its oversight,” Moran said in an interview.

The FAA and NTSB declined to comment on the briefing.

Boeing said CEO David Calhoun visited the Wichita factory of Spirit AeroSystems, which makes a large part of the fuselage on Boeing Max jets and installs the part that came off an Alaska Airlines jetliner. Calhoun and Spirit CEO Patrick Shanahan — a former Boeing executive and acting U.S. defense secretary whose nomination by President Donald Trump to lead the Pentagon failed — met with about 200 Spirit employees in what the companies termed a town hall.

“We’re going to get better” because engineers and mechanics at Boeing and Spirit “are going to learn from it, and then we’re going to apply it to literally everything else we do together,” Calhoun said.

Shanahan told the workers that by working with the NTSB, FAA, the airlines and Boeing, “we will restore confidence.”

The meeting of CEOs occurred as both companies face scrutiny over the quality of their work.

An Alaska Airlines Max 9 was forced to make an emergency landing on Jan. 5 after a panel called a door plug blew out of the side of the plane shortly after takeoff from Portland, Oregon.

The NTSB is investigating the accident, while the FAA investigates whether Boeing and its suppliers followed quality-control procedures.

Alaska and United Airlines, the only other U.S. airline that flies the Max 9, reported finding loose hardware in door plugs of other planes they inspected after the accident. Both airlines have canceled hundreds of flights while their Max 9s are grounded.

Boeing shares gained 1% on Wednesday but have dropped 18% since the accident, making the Arlington, Virginia, company the worst performer in the Dow Jones Industrial Average in that span.