View Full Version : Note: April 5th! Additional Software Problem Found In Boeing 737 Max Control System:

16th May 2019, 00:14
This article, and many like it, popped up on April 5th. Within a few days, it was forgotten. What was the problem? Was it fixed? I never saw any sort of resolution...it just disappeared. https://www.ndtv.com/world-news/additional-software-problem-found-in-boeing-737-max-control-system-officials-2018200

But later Thursday, Boeing confirmed to The Washington Post that it had found a second software problem that the Federal Aviation Administration has ordered fixed - separate from the anti-stall system under investigation in the two crashes, and that had led to the aircraft's worldwide grounding.That additional problem pertains to software affecting flaps and other flight stabilization hardware and is therefore classified as critical to flight safety, said two officials who spoke on condition of anonymity to discuss the ongoing probe.

"Critical to flight safety", but I don't think we have heard any more about it. If someone knows what it was, how and if it was fixed, I'd like to know, too. The MCAS system has been beaten to death, but this seems to have been forgotten.

Bend alot
16th May 2019, 05:33
With the below link, the fact Boeing have not supplied the required documents requested, and the FAA said that they were not aware of any safety risks reported from Boeing on the MAX.

So untruths are floating around some key players.


16th May 2019, 08:12
The article fails to clarify what the exact nature of the problem was.

Relating the report to the ET piloting actions in the accident, could conclude that the issue is about the ineffectiveness of the AD emergency drill, which was based on the Trim Runaway drill. The FAA have launched an investigation into this.

Alternatively the issue could be a re-run of the AoA Disagree alert option which was not working in some aircraft. A superficial view might conclude that the modification was not enabled - ‘we paid for it, but it was not delivered’. In isolation, not a particular safety issue, but of greater concern if used with another option of AoA display.

More recently, the absence of the alert has be interpreted as the failure of the software to detect differences in AoA and thus provide a display; the modification was correctly enabled, but it did not work. Again in isolation this is not a safety issue - ‘so don’t tell operators they will want a fix which costs time and effort during a demanding certification programme’.

However, HOWEVER; the use of this software comparison logic in the proposal to alleviate AoA Disagree in MCAS indicates an appalling lack of understanding across departments or external vendors, and a significant weakness in the checking and validation process - design and certification.

The errors were only detected during regulatory assessment of the proposed modification (FAA / other regulatory agencies). Thence the proposal was rejected and Boeing invited to resubmit proposals for modification - a low key, polite, regulatory rejection, likened to WIHIH (with some hidden embarrassment as to why the original fault was not detected).

This ‘double-double’ error, design and process, which if extended across other products further reduces confidence on how things have been done. Not that these are unsafe, but perhaps that not all of the advanced (dual / triple) safeguards have the expected depth of redundancy.

The magnitude of the latter interpretation drives one to use pictures - and some levity, but so true.

Less Hair
16th May 2019, 09:13
Might have been the missing AoA disagree warning indication?

16th May 2019, 10:10
Might have been the missing AoA disagree warning indication?

No, if we trust the quote in the first post (https://www.pprune.org/rumours-news/621580-note-april-5th-additional-software-problem-found-boeing-737-max-control-system.html#post10472226), also found in a slightly different form on WSJ (https://www.washingtonpost.com/world/africa/ethiopia-says-pilots-performed-boeings-recommendations-to-stop-doomed-aircraft-from-diving-urges-review-of-737-max-flight-control-system/2019/04/04/3a125942-4fec-11e9-bdb7-44f948cc0605_story.html?noredirect=on&utm_term=.09d83d11d93d) (possibly paywalled) and on MSN (https://www.msn.com/en-us/news/us/additional-software-problem-detected-in-boeing-737-max-flight-control-system-officials-say/ar-BBVBQQo)
That additional problem pertains to software affecting flaps and other flight-control hardware and is therefore classified as critical to flight safety, said two officials with knowledge of the investigation.

ATC Watcher
16th May 2019, 10:36
The CEO of Ethiopian is 2 different interviews with Richard Quest , broadcast on CNN , mentioned that their flight had also encountered "flight control issues " different from MCAS , he said he asked Boeing about it and was still waiting for the answers..
I mentioned this before in the previous thread, still wondering is there is something more coming out, or if the ET CEO was just fishing..