WASHINGTON (Reuters) -The chair of the Senate Commerce Committee wants the Federal Aviation Administration to conduct a thorough review into its oversight of Boeing and other manufacturers, raising serious questions about the government's scrutiny of the planemaker.

"While the FAA has rightly focused on Boeing's production quality shortcomings, I am concerned about whether FAA action -- or inaction -- contributed to Boeing's problems," Senator Maria Cantwell said in a letter first reported by Reuters to FAA Administrator Mike Whitaker.

She said the FAA in April disclosed that it had conducted a combined total of 298 audits of Boeing and Spirit AeroSystems over the prior two years that "did not result in any enforcement actions."

The FAA and Boeing did not immediately comment.

Cantwell said in her letter dated Saturday "a root cause analysis would ensure both Boeing and FAA have discovered the core causes of problems, rather than just symptoms." She wants the analysis "to identify any deficiencies in its own oversight of Boeing and other manufacturers" and to "develop corrective actions and a plan for implementing them."

After a Jan. 5 mid-air emergency involving a new Alaska Airlines 737 MAX 9 that lost a door plug at 16,000 feet, the FAA conducted a 737 MAX production audit into Boeing opens supplier Spirit and found multiple instances where the companies had failed to comply with manufacturing quality control requirements.

Last month, Whitaker said at a Senate Commerce hearing that the FAA was "too hands off" in oversight of Boeing before January. "The FAA should have had much better visibility into what was happening at Boeing before Jan. 5," Whitaker said.

The FAA's approach before the mid-air incident was "too focused on paperwork audits and not focused enough on inspections," Whitaker added. "We will utilize the full extent of our enforcement authority to ensure Boeing is held accountable for any noncompliance."

Whitaker in February barred Boeing from boosting production of its best-selling plane. Whitaker also said the agency will continue increased on-site presence at Boeing and Spirit for the foreseeable future.

The National Transportation Safety Board said earlier the door panel that flew off a Boeing 737 MAX 9 jet mid-flight was missing four key bolts and no paperwork exists for the removal of those bolts. Whitaker confirmed no paperwork exists.