FAA Gives Preliminary Approval for 737 MAX Fixes
Matthew Greenwood posted on August 10, 2020 |
Agency’s airworthiness directive is open for public input.

The FAA has given Boeing preliminary approval for its proposed fixes for the troubled 737 MAX—along with an airworthiness directive that the planemaker has to comply with.

At the heart of the review is a fix of the MCAS software that investigators believe caused two fatal crashes and led to the global grounding of the MAX fleet.

The agency will require that Boeing install a software patch to the MCAS that implements new safeguards. There are four components to the FAA’s directive:

First, the software patch to the MCAS requires that the system rely on two angle-of-attack sensors, rather than just the one that the 737 relied on previously. A warning light would be installed in the cockpit to alert pilots of a malfunctioning sensor. The FAA will also require that technicians inspect the sensors before the planes are flown.

Second, if there is a certain level of disagreement between the sensors, the MCAS would be disabled for the rest of the flight. This would further safeguard that the MCAS doesn’t trigger based on faulty sensor data.

Third, the MCAS will be less aggressive when triggered. The previous system overpowered the pilots of the doomed flights, forcing the planes downwards despite the resistance of the crew.

And finally, the MCAS will only be allowed to activate once rather than continually re-engaging. If the pilots override it, it remains off for the remainder of the flight.

The FAA’s recommendations come at the end of a lengthy review and analysis of the two crashes that grounded the MAX around the world. The review included over 50 hours of flight and simulator tests, and analysis of over 4,000 hours of Boeing’s flight and simulator testing. Flight crews from the planemaker, as well as American and international airlines that use the 737 in their fleets, provided feedback to the FAA.

More on the proposed changes to the MCAS.

The fixes don’t end with the MCAS. The FAA also wants some wiring rerouted, as well as changes to operations and maintenance processes—which would include updated pilot emergency checklists.

But the proposed fixes don’t cover air data and crew alert systems—which were called archaic and dangerous by Boeing engineer and whistleblower Curtis Ewbank in his testimony to the U.S. Senate.

The FAA’s proposal has been released for public comment for 45 days, a period ending on September 21, 2020. Depending on the feedback received, the agency could finally clear the 737 MAX for return to service as early as late October—two years after they were originally grounded.


Read more about the 737 MAX disasters at Boeing 737 MAX Pilots Had No Idea What They Were Up Against.

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