April 1 (UPI) -- The Federal Aviation Administration said Monday it expects to receive Boeing's final package of software updates for its grounded 737 Max 8 aircraft in 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 FAA said that once it receives the updates, they will be subjected to a "rigorous" safety review.
"The FAA will not approve the software for installation until the agency is satisfied with the submission," it said.
Boeing and its fastest-selling aircraft have come under scrutiny following last month's crash of an Ethiopian Airlines plane that killed 157 people and grounded Boeing's new 737 Max 8 worldwide.
A preliminary report on the crash was expected to be completed Monday, the Ethiopian foreign ministry said. Its findings of which could confirm a theory that the jetliner's anti-stall system malfunctioned -- the same flight system suspected to have caused another Max 8 to crash in Indonesia last fall, killing 189 people.
On the plane's cockpit voice recorder, a pilot is heard yelling, "pitch up, pitch up" in the moments before the crash -- a possible indication the automated system had forced the aircraft into a dive, the standard maneuver for recovering from a stall. An airplane enters a stall when it no longer has enough speed to generate lift beneath the wings. The best way to recover is to put the plane's nose down, an attempt to pick up speed, and regain lift -- but only as long as there's sufficient altitude to perform the maneuver.
The Indonesia crash prompted Boeing to work on a software fix and the company was close to finishing it when the Ethiopian plane went down. Officials said pilots from various airlines are now testing the system in flight simulators. Boeing unveiled the software update last week.
As the investigation moves forward, the U.S. Transportation Department is looking into what caused both crashes and how the FAA certified the plane to fly. The 737 Max 8 entered service in 2017.
The FAA said last week it will increase oversight by this summer. Acting FAA chief Daniel Elwell told Senate lawmakers an amended certificate had been given Boeing because the Max 8 and Max 9 were very similar to the company's older 737 models. A Max 10 is presently waiting to enter service.
Connecticut Sen. Richard Blumenthal said the FAA's actions sacrificed safety in favor of cutting costs.
"The fact is the FAA decided to do safety on the cheap which is neither cheap nor safe and put the fox in charge of the hen house," he said at last week's hearing.