correct, but, but what I am reading here that now cracks are being found on airframes with lower number of cycles (27K) as compared to the advisory (30K)

Jeroen

I think the advisory was to check ALL 737NGs, but starting with those which had more than 30K landings.
But aren't these (pickle forks) supposed to last the life of the airframe.

I know absolutely not related, but on first reading about these cracks, thoughts went to this and this .

Regards
Sutripta

^^^^^^^
For the benefit of our readers, especially those not from aviation, the photo shows what a pickle fork is. There are 4 of them and take the full load of joining the wing to the fuselage. A wing can fly by itself but you want the fuselage with its passengers and cargo to fly too, and hence. The 4 pickle forks are designed to flex and are meant to last the full life of, in this case, 90,000 cycles of take-offs and landings. An ex-Jet Airways' 737NG was undergoing conversion to a freighter and the occasion is always taken to check all load bearing structures which normally lie hidden behind other equipment. That's when a one inch long crack was found. This led to communication up to Boeing & the FAA and the release of this airworthiness directive. I suspect this is a problem with the metal alloy used for a given batch. Older 737NGs have undergone 'D' checks and no such crack was found. What does a crack mean. We often come across cracks measured in mm or less in several parts of an aircraft. Depending on the part and the crack you can take a call on repair now or wait. However a 30mm crack in a load bearing structure becomes significantly more worrisome as it can expand rapidly under the stress of flight.

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I just came across this article:

https://leehamnews.com/2019/11/01/a-...0s/#more-31553

Very interesting. It describes how the 707 went through it is testing and certification. Notably, in the UK, it ran into the formidable Davies, I mentioned earlier, who demanded various modifications. I did not know, but apparently the production of 707 was stopped for some 10-11 months. All because Davies demanded certain modification that would prevent line pilots potentially entering a stall.

Next it also discussed another modification made on later 707-400 versions, again demanded by Davies.

The system installed in the 707 - 400 is somewhat different than MCAS. But the main difference is perhaps how it came about. The author stresses the need to have any plane test flown, extensively, by different authorities.

What is interesting to note, is that all these aircraft, at the time, did have an airworthiness certificate from the FAA as far as I am aware.

But Davies withheld the Air Registration Board approval (nowadays that is called the CAA).

It would be interesting to think through what would have happened to the Max during its certification if the FAA had a Davies type of person involved.

Jeroen

Or even in the EASA


Regards
Sutripta

Boeing CEOs take (2 min soundbite!)
https://www.wsj.com/video/boeing-ceo...824262605.html

Regards
Sutripta

Well, at least he plainly calls himself (and Boeing) accountable.

Which is important. Accountability can not be shared or delegated.

Jeroen

^^^
Could he have said anything else?
I see it more as a 'am following the tradition of captain goes down with his ship'.

Regards
Sutripta

Maybe, maybe not. You can never be sure how these things play out. He could have tried to be a little more elusive, he could have said he was responsible, which would have had a different meaning.

But the guy is on his way out, that is for sure. It will just be a matter of time and how much Boeing will pay him.

Jeroen

^^^
So board to CEO - 'If you don't fall on your sword, 737Max rather than golden parachute for you, me boy'.

Regards
Sutripta

Hindsight is 20/20. Still interesting read.
https://www.theatlantic.com/ideas/ar...arings/602188/

Somewhere else I read that many people consider the 777 to be the last 'real' Boeing. Lets see if I can find that article.*

Regards
Sutripta

* Google is consistently referring to the New Republic article, one which has been linked to in this forum before. The other articleI can't find anymore.

Now to shift focus to the operators.
https://www.nytimes.com/2019/11/24/w...indonesia.html

Regards
Sutripta

Thanks for those two interesting articles.

I think it is highly appropriate to also look at the carriers involved. Everybody jumped onto the "blame Boeing bandwagon" early on. Given how badly Boeing and the FAA messed up on this MCAS understandable.

Lion air could have prevented this accident from happening in the fist place. Their dismissive attitude on the accident report is telling and hugely worrying.

Again, you can not make excuses for a such a poor design and certification process as we have seen with this whole MCAS mess.

Still, aviation safety is what it is because of having a safety conscious operation in place everywhere, not just at the design of the aircraft.

Jeroen

As a fall out of this whole 737 MAX, MCAS debacle, a lot of articles are appearing about the reliability of software in general.

An interesting case recently poppep up:

https://www.itpro.co.uk/business-int...raffic-control

People are making a case of it against the MAX, because no matter what it will rely on software to keep within its flight envelope.

This UK experience brought back memories for me. I have had a very similar experience once, where software that had been running for almost 15 years all of sudden had a major problem, due to to a design error made 16-17 years earlier. It had never popped up, had never been found during testing, or in fact in operation across the world with many customers.

Fixing and trouble shooting “old” software can be a real challenge. After such a time very few people might have any insights into the code, the programming language etc. I feel these days that has become even worse. Everybody wants to work on the latest and the greatest, not 5 year old stuff, let alone older stuff.

For all its high tech appearances, some parts and components in the aviation industry are generations behind the latest and the greatest. Part of that is due to enormous cost of cerfitifiying parts and components.

As some other articles eluded to, part of what the MCAS debacle has brought is the need to design aircraft, relying on a different set of piloting skills. In fact, many people are advocating this also as part of the shortage of pilots in the decades to come. No matter what, we will see more pilots with less experience manning the cockpits.

The only way to overcome that is to automate more. And thus rely more on software. Catch 22 I think. At some point in time, we will have an aircraft getting into problems due so a 20 year old bug that never materialised before.

Jeroen

Jeroen

When a system is running well enough but needs some refinement, the "Don't fix it if it ain't broke" attitude rules and the job isn't done. When the system is broken and many years have passed, there is nobody left who understands what and how to fix it.

Automation is essential, but in my view the only way to avoid ending up in the situation mentioned above is to deploy artificial intelligence systems. These, like humans, can learn and self-correct and evolve with changing needs.

But AI is tricky; can we trust it in safety-critical systems? Humans are social beings, understand morality, the concept of action and consequences, and seek social approval and respect. What is to stop an AI system from killing us all even if it is following the laws of robotics https://en.m.wikipedia.org/wiki/Laws_of_robotics?