Newly stringent tests spur major software change for 737 Max

[Yo_Mama_Been_Loggin]

SEATTLE — While conducting newly stringent tests on the Boeing 737 Max flight control system, the Federal Aviation Administration (FAA) in June uncovered a potential flaw that now has spurred Boeing to make a fundamental software-design change.

Boeing is changing the Max’s automated flight-control system’s software so that it will take input from both flight-control computers at once instead of using only one on each flight. That might seem simple and obvious, but in the architecture that has been in place on the 737 for decades, the automated systems take input from only one computer on a flight, switching to use the other computer on the next flight.

Boeing believes the changes can be accomplished in time to win new regulatory approval for the Max to fly again by October. Significant slipping of that schedule could lead to a temporary halt in production at the Renton plant where 10,000 workers assemble the 737.

After two deadly crashes of Boeing’s 737 Max and the ensuing heavy criticism of the FAA for its limited oversight of the jet’s original certification, the agency has been reevaluating and re-certifying Boeing’s updated flight-control systems.

https://www.heraldnet.com/business/newly-stringent-tests-spur-major-software-change-for-737-max/

Redundancy

[RainCaster]

1. There are so many design problems with that software

It scares me to think how many other software design flaws there are in those airplanes.

Nobody is doing design work as if lives depend upon it, and management doesn't seem to care. Deadlines and budgets are the priority here.

[Sherman A1]

2. The software is certainly a huge issue

That the airframe itself is so poorly designed as to need the software and what appears to be an endless series of patches is to me much more disturbing.

[Yavin4]

4. Maybe the design work was outsourced to a cheaper labor market abroad

in order to save money. Gotta maximize those shareholder profits now.

[rickford66]

3. Having worked on simulators for over 35 years, I think this was a great article.

I have seen some "quick" or "dirty" fixes in flight control software, and slight changes require loads of redundancy testing and new tests need to be added. I've never "flipped bits" within a processor, but did introduce malfunctions of the inputs. When we found glitches or bugs with any avionics, we reported such data to the proper manufacturer. Most modern avionics have an input to let the box know it's on a simulator, otherwise the software could get confused when we would do something impossible, but it also allows introducing scenarios as outlined in the article.

[harumph]

5. Fundamentally, this isn't a software "issue" - it's an mechanical engineering issue

they're attempting to "fix" with software. The plane is unbalanced which can
result in a bad situation that human pilots can't react to quickly enough - hence the attempted
software fix to preempt said bad situation. Structural additions were rushed into the 737 without
taking it back to zero in order to compete with Airbus which spent the money to substantially retool
a thus did better job at engineering a flight worthy plane.

The 737 Max isn't the regular 737 (which is a dependable plane). In other words, the 737 Max is structurally
distinct (the software is to fix the inherent instability they introduced with the structural changes).

[GulfCoast66]

6. I've read that some of our newest fighter planes are so inherently unstable,

A human needs a computer making adjustments to keep it in the air. But that is by design and allows for incredible performance. Not sure how true that is.

But it seems a bad scenario for a passenger plane. After all, they are not going into combat or anything. The main thing they need to do be safe.

[Yo_Mama_Been_Loggin]

7. The now retired F-117 stealth fighter was one such plane

In 1964, Pyotr Ufimtsev, a Soviet mathematician, published a seminal paper titled Method of Edge Waves in the Physical Theory of Diffraction in the journal of the Moscow Institute for Radio Engineering, in which he showed that the strength of a radar return is related to the edge configuration of an object, not its size. Ufimtsev was extending theoretical work published by the German physicist Arnold Sommerfeld. Ufimtsev demonstrated that he could calculate the radar cross-section across a wing's surface and along its edge. The obvious and logical conclusion was that even a large aircraft could be made stealthy by exploiting this principle. However, the airplane's design would make it aerodynamically unstable, and the state of computer technology in the early 1960s could not provide the kinds of flight computers which allow aircraft such as the F-117 and B-2 Spirit to stay airborne. However, by the 1970s, when Lockheed analyst Denys Overholser found Ufimtsev's paper, computers and software had advanced significantly, and the stage was set for the development of a stealthy airplane.

https://military.wikia.org/wiki/Lockheed_F-117_Nighthawk

[dalton99a]

8. Excellent, well-written article