The Federal Aviation Administration (FAA) must work to restore "public confidence" in aircraft certification efforts after two deadly Boeing 737 MAX crashes, the U.S. Transportation Department's inspector general said Wednesday in a report seen by Reuters.

The long-standing practice of delegating certification tasks to aircraft manufacturers has come under criticism from lawmakers and others after the two crashes, which killed 346 people.

The report, dated Oct. 23 but not yet publicly released, said the FAA faces a "significant oversight challenge" to ensure that companies conducting those tasks "maintain high standards and comply with FAA safety regulations."

The report said that by March 2020, the FAA plans to introduce "a new process that represents a significant change in its approach to overseeing" aircraft designation efforts.