In a letter to Congress, Boeing has admitted that it cannot find records for work done on a door panel that blew out on an Alaska Airlines flight over Oregon two months ago.

“We have looked extensively and have not found any such documentation,” Ziad Ojakli, Boeing executive vice president and chief government lobbyist, wrote to Sen. Maria Cantwell on Friday, reported AP.

Boeing said its “working hypothesis” was that the records regarding the removal of panel and reinstallation on the 737 MAX final assembly line in Renton, Washington, were never created, even though the company’s systems required it.

The letter followed a controversial Senate committee hearing on Wednesday in which the company and the National Transportation Safety Board argued over whether Boeing had cooperated with investigators.

Boeing repeatedly denied identifying employees

Jennifer Homendy, the safety board’s chair, testified that for two months Boeing repeatedly denied identifying employees who work on door panels on Boeing 737s. The company failed to furnish documentation about a repair job that included removing and reinstalling the door panel.

Since the January 5 incident in which a panel that plugged a space left for an extra emergency door blew off an Alaska Airlines Max 9, Boeing has been under increasing scrutiny.

There were no injuries, and the pilots were able to land safely.

Recently, the Federal Aviation Administration gave Boeing 90 days to communicate how it will reply to quality-control problems raised by the agency and a panel of industry and government experts.