The head of the Federal Aviation Administration told lawmakers Tuesday that a door blowout on an Alaska Airlines plane last month showed that the agency needs to strengthen its methods for ensuring Boeing is building safe aircraft.

That incident, FAA Administrator Mike Whitaker told lawmakers during his first appearance before Congress, created two questions for the FAA — “One, what’s wrong with this airplane, but two, what’s going on with the production at Boeing? There have been issues in the past and they don’t seem to be getting resolved.”

For now, the FAA has added 26 inspectors — 20 at Boeing’s Renton, Washington 737 MAX production facility, and six at Kansas-based contractor Spirit Aerosystems — as it tries to get a handle on exactly what more needs to be done.

Whitaker did concede during the hearing that the agency’s current oversight system, which primarily involves auditing paperwork produced by Boeing employees, is not adequate.

“I think we’re going to need more boots on the ground,” Whitaker told the panel. “We’re going to need more inspectors. We don’t have that many inspectors on the aircraft certification side of the house.”

In addition, Whitaker said the FAA is in the middle of a six-week audit as well as a probe into Boeing’s safety culture — ordered up after the last 737 MAX disasters in 2018 and 2019 — that is due at month’s end.

Whitaker said those two things “will give us guidance” on whether further changes are needed to the way the FAA delegates authority to Boeing and its contractors to sign off on the safety of its own aircraft, with FAA oversight.

“I’ve heard Boeing’s CEO mention an option for third party quality control,” he said, indicating that an independent evaluator — separate from both Boeing and FAA — might be called for. “I think it’s important that we look at all options on the table and understand how do we make changes that are going to give us a different result.”

Still, Whitaker said he is “confident” that his agency has the tools it needs to address challenges facing the aviation system.

At Tuesday’s hearing, ranking member Rick Larsen (D-Wash.) said he — and his fellow committee members — support “the FAA’s decisive response to this accident, which included grounding the affected 737 MAX 9 fleet, a separate investigation into whether Boeing delivered a non-compliant aircraft to its customer, an overarching audit of Boeing’s 737 MAX production lines and its suppliers and a prohibition on increasing Boeing’s 737 MAX production rate until its quality control issues are resolved.”

All 171 of Boeing’s 737 MAX 9 planes in the U.S. were grounded after the Jan. 5 Alaska Airlines incident, pending inspections. Though a majority of those planes have been addressed and are back flying, Boeing is still being held to a production rate of 38 MAX planes a month, though the company wants to get back to 50.