Boeing has found a second software problem with the grounded 737 Max, separate from the anti-stall system that contributed to the Ethiopian Airlines crash.
The additional problem explains why Boeing delayed submitting fixes for its stall-prevention system to the US Federal Aviation Administration for review last week, reported the Washington Post.
An FAA spokesman said on Monday they are expected to received the long-awaited fix, which is intended to prevent incidents like those in Ethiopia and Indonesia that have claimed 346 lives within months, 'over the coming weeks'.
Boeing said in a statement on Thursday they 'have identified an aspect of the software, unrelated to MCAS, that will also be addressed as part of the software update'.
Ethiopian Airlines crash: Pilots cleared and 'had no control over 737 Max'
The problem has been addressed by Boeing as a 'relatively minor issue'.
The company added that they already had a solution for the problem.
"Over the coming week, we will finalise the development of our update for certification by the Federal Aviation Administration, taking a comprehensive, disciplined approach to get it right," it read.
The preliminary report of the Ethiopian Airline crash found the pilots had correctly followed emergency procedures.
Ethiopian Airlines 737 crash: Cause of fatal accident that killed 157 'revealed'
It's said the plane's nose was forced to dive four times by the automated system and each time, the pilot fought unsuccessfully to regain control of the plane.
It's because the manual wheel meant to bring up the nose back up was 'not working', stated the report.
The airliner eventually dived at 40 degrees and crashed into the ground at 575 mph.
Ethiopian Airlines crash investigators reach 'conclusion' using black box data
Dagmawit Moges, Ethiopia's minister of transport, said in a news conference in the capital city Addis Ababa: "The crew performed all the procedures repeatedly provided by the manufacturer but was not able to control the aircraft."
She also said Boeing should carry out a full review before the allowing the 737 Max back into the air.
The MCAS is an automated stall prevention system that if triggered can, under certain circumstances, try to force down the nose of the plane even if pilots are flying it manually, leading to a steep dive.
The 737 Max has now been grounded worldwide after the Ethiopian accident, which followed the Lion Air crash in October.
