The Federal Aviation Administration said Monday it expects Boeing to submit the final software fix for the 737 Max jet “over the coming weeks.”

“Time is needed for additional work by Boeing as the result of an ongoing review of the 737 MAX Flight Control System to ensure that Boeing has identified and appropriately addressed all pertinent issues,” the FAA said in a statement.

The agency and Boeing are under fire following two fatal crashes of its popular 737 Max jets since October. The FAA said it will conduct a “rigorous safety review” and the software that’s suspected as contributing to both crashes won’t be installed until its satisfied.

The plane has been grounded since mid-March following the deadly accidents where a part of the aircraft’s flight control system is suspected of causing, at least in part, the crashes that killed all 346 people aboard the jets.

Boeing believes it has solved issues with the 737 Max automated stall prevention system by updating the plane’s software, cockpit alerts and pilot training.

As Boeing and investigators studied the brief flights of the Lion Air plane that plunged into the Java Sea in Indonesia on Oct. 29 and the Ethiopian Airlines crash on March 10, the scariest similarity was the way both flights pitched up and down before crashing.

Later Monday, Boeing said it continues to work with the FAA and other regulatory agencies worldwide to identify and address all issues.

“Safety is our first priority, and we will take a thorough and methodical approach to the development and testing of the update to ensure we take the time to get it right,” Boeing said in a statement.

Many believe the automated stall prevention system — the Maneuvering Characteristics Augmentation System, or MCAS — continually pushed the nose of the plane down despite the pilots repeatedly trying to correct the move. The new software will allow the system to push the nose of the plane lower just once and only for 10 seconds at most.

The airplane maker unveiled some of its fixes to pilots, regulators and the media last week.

Boeing’s stock dipped less than a percent in extended trading after closing up more than 2 percent Monday.