The Federal Aviation Administration’s top official told a House panel on Tuesday that the agency would step up its on-the-ground presence monitoring Boeing’s aircraft production.

The official, Mike Whitaker, appeared before lawmakers one month after a door panel blew out of a Boeing 737 Max 9 jet while in flight, raising new questions about Boeing’s quality-control practices, as well as the F.A.A.’s oversight of the plane maker.

“Going forward, we will have more boots on the ground closely scrutinizing and monitoring production and manufacturing activities,” Mr. Whitaker said in his opening statement before the House Transportation and Infrastructure Committee’s Aviation Subcommittee. “Boeing employees are encouraged to use our F.A.A. hotline to report any safety concerns.”

The episode with the door panel, known as a door plug, occurred on an Alaska Airlines flight shortly after it took off from Portland, Ore., on Jan. 5. The F.A.A. quickly grounded similar Max 9 jets. In late January, it said they could return to the skies after being inspected.

“Our No. 1 priority is safety,” Mr. Whitaker told lawmakers. “Recent events, especially the Jan. 5 incident involving the Boeing 737 Max 9, have shown us we can’t become complacent when it comes to maintaining safety and public confidence in the aviation system.”

The National Transportation Safety Board said on Tuesday that it would release its preliminary report about the episode later in the day.

Over the past month, the F.A.A. has staked out a hard line against Boeing, barring the company from expanding production of the 737 Max series until it addresses quality-control issues. It is yet another crisis for the plane maker involving the Max, coming on the heels of two deadly crashes involving Max 8 jets in 2018 and 2019.

The episode with the door plug has also prompted scrutiny of the F.A.A.’s track record monitoring Boeing and its longstanding practice of allowing the plane maker’s employees to perform safety work on the government’s behalf.