The 737 MAX 9 lost a large panel from its fuselage, forcing pilots into an emergency landing.
No one was seriously hurt, but the incident raised big questions about how Boeing's top-selling jet is made.
On Tuesday, Chief Executive Dave Calhoun said the plane maker acknowledged failures over quality control.
He said Boeing would approach the problem with 100% transparency, and ensure there was no recurrence.
U.S. watchdogs have grounded 171 of the planes for checks, with airlines around the world also taking the jets out of service.
Concerns had deepened after United Airlines said it had found loose bolts on some of its aircraft.
On Tuesday, White House spokesperson Karine Jean-Pierre said travelers had a right to feel safe:
"And in that spirit, these particular Boeing aircraft will remain grounded until operators completely complete enhanced inspections."
The MAX was already under scrutiny following two earlier fatal crashes.
Those incidents were traced to a design fault that was subsequently fixed.
But the jet has since been plagued by numerous production and quality control issues, threatening deeper damage to Boeing's reputation.
Calhoun said the new drama had left customers "very anxious".
Figures out this week showed Boeing hit its jetliner production targets for 2023, but lagged arch-rival Airbus for the fifth year running.
