Boeing left 737 Max review work undone

I believe the cause of two crashes of Boeing 737 Max jets was not the result of design flaws but was result of flawed system integration.

It is accepted engineering practice that when the form, fit or function of a part, component or system is changed a thorough analysis or evaluation needs to be done. When Boeing incorporated the larger engines on 737, the flight characteristics of the plane were affected. There should have been a review of its impact on every critical flight control system, not just selected ones.

Boeing’s Maneuvering Characteristics Augmentation System (MCAS) was designed so its actuator receive input from one air sensor (known to have output issues) not multiple sensors as designed into other systems. An analysis of the MCAS system should have identified this as a critical flaw and should have resulted in a redesign to eliminate this critical system flaw.

When 737 MAX flight test results showed that MCAS actuator caused the horizontal stabilizer to move further than expected, an analysis should have showed that the jackscrew would receive high loads that would negate the pilot ability to use the manual trim control to control roller coasting of the airplane after a few oscillations.

Boeing seems to have accept the psychology that “there is not enough time to get something right but enough time to redo the work.”

Robert J. Creamer

Everett