Boeing Co. will provide airlines that have bought the 737 MAX with free software upgrades, the U.S. manufacturer said on Monday, as Ethiopian Airlines told Reuters it expected a preliminary crash report this week or next.

Any fixes to the MAX software, the focus of investigations in two deadly crashes that have prompted worldwide groundings of the aircraft, must still get approval from governments around the world.

The U.S. Transportation Department said Monday it is forming an outside panel to review the Federal Aviation Administration's aircraft certification program amid growing concerns after two fatal Boeing 737 MAX crashes since October.