Audit of Boeing’s 737 Max fixes could keep the plane grounded longer

Regulators overseeing changes on Boeing Co.’s 737 Max rejected an audit of how the software was being developed, prompting the company to make revisions and possibly slowing the return of the jetliner to service, according to a person familiar with the action.

The issue with Boeing’s audit was brought up in recent days at a meeting in a Collins Aerospace Systems facility in Cedar Rapids, Iowa, attended by officials from the Federal Aviation Administration and the European Aviation Safety Agency, the person said.

Boeing and Collins — a United Technologies Corp. division that developed computer automation on the 737 Max — are making changes to a safety feature on the jet that was involved in two fatal crashes of the plane that killed a total of 346 people. As a result of testing in recent months, Boeing is also undertaking a more complex revision of how the flight computers on the plane function.

Full audit results are required before final simulator tests of the changes can be conducted. Depending on how long it takes to satisfy the FAA and European regulators, it could push back a certification flight test and regulators’ final decision on lifting the flight ban by a few days or even weeks, said the person.

Boeing said it provided technical documents to regulators “in a format consistent with past submissions.�

“Regulators have requested that the information be conveyed in a different form, and the documentation is being revised accordingly,� Boeing said in a statement. “While this happens we continue to work with the FAA and global regulators on certification of the software for safe return of the Max to service.�

European Aviation Safety Agency spokeswoman Janet Northcote said that after the Iowa meeting, her agency’s executive director, Patrick Ky, said: “We think there is still some work to be done.� Northcote declined to specify the issues.

The issues with the audit were earlier reported by Reuters.

Levin writes for Bloomberg.