Boeing now seeks more time

Boeing Co says it needs more time to finish a software upgrade for its grounded 737 Max jetliners as company engineers update a stall-prevention system linked to two fatal crashes in five months.

The planemaker said last week it would submit final paperwork for the revamp to the Federal Aviation Administration by March 29 to make the system -- known as MCAS -- less aggressive in pushing down a plane’s nose, and to add redundancy so that it’s less likely to activate when other systems malfunction. Now Boeing says the update won’t be ready until the “coming weeks.”

An issue with integrating the software fix and the plane’s existing flight-control architecture came to light as Boeing did a final audit of the upgrade, according to a person briefed on the work. Ensuring that MCAS will perform as desired while not interfering with existing flight controls isn’t expected to be a significant challenge said the person, who wasn’t authorized to speak about the work and asked not to be identified.

“We are working to demonstrate that we have identified and appropriately addressed all certification requirements and will be submitting for FAA review once completed in the coming weeks,” Boeing said in an email Monday. “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.”