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Smoke in the cabin of two 737 MAX caused by Load Reduction Device system [video]

MobiusHorizons

I found this to be a fascinating dive into a potentially serious safety concern. I was impressed how simple the mitigations could be based on the recommendations in the report. I find the evidence credible for an attempt to burry the issue, but honestly I don't understand the motivation. At this stage I feel Boeing and the FAA could really stand to gain some good press from being extra proactive about such issues. Especially when the proposed mitigations seem like they would be relatively easy to implement, and should not be expensive for airlines from what I can see. It seems like the source being the engine manufacturer and consequently having the potential of affecting other jets including potentially the airbus A320 would only improve the incentives for Boeing to get out ahead of this, and demonstrate a safety culture. Does anyone understand the motivations that could lead to the response we have seen from the FAA and Boeing?

apical_dendrite

From what I've read, CFM and Boeing committed back in December to making the software fix that's suggested in the video. https://aerospaceglobalnews.com/news/bird-strike-incident-se...

Why FAA and EASA didn't require any procedure changes in the interim to prevent the issue is a very good question.

MBCook

Can they force an install? Or will it be a choice?

I like Mentor Pilot and Air Disasters, so I know I’ve heard of a few where the problem that caused an accident was already known and a fix was available but the airline just chose not to do it because they had that option. Or it was scheduled but hadn’t been performed yet because it wasn’t thought to be that critical.

Having the FAA mandate the fix seems like it would be a much better option.

V99

Yes the FAA can issue what are called Airworthiness Directives and require an issue be resolved in the timeframe and manner they specify.

The timeframe could be anything, but common forms are like:

- Within the next X (flight) hours or Y calendar days

- You don't have to, but additional inspection needed every X hours or Y days until you do

- At next annual inspection

- Immediate/before flying again (usually called an Emergency AD)

dz0ny

This is a issue that may also affect Airbus aircraft, but so far, it has only caused problems on two Boeing planes. Like MCAS, it was not disclosed to pilots, prompting the FAA to recommend design changes and notify flight crews.

https://simpleflying.com/boeing-cfm-international-update-737...

K0balt

Unfortunately, it seems that the internal FAA recommendations were not allowed to make their way into any kind of airworthiness directive.

The recommendations include very basic procedure changes that mitigate the near term risks without any significant impact to operation, as well as recommendations for what probably amounts to a software change and upgrades to some of the pilot oxygen masks to effect a permanent fix.

The only reason that we even know about the internal recommendations is that they were leaked to the press.

Boeing released a pilot bulletin that basically says to go through the checklist quickly and to treat smoke in the cabin as a major failure, but stops short of recommending some very, very simple steps in aircraft configuration prior to takeoff that would completely mitigate the issue without negatively effecting flight performance.

The major recommendation in the internal FAA bulletin is to use the APU bleed instead of the main engine bleed air to power the air conditioning and cabin pressurisation during the takeoff phase of flight, below 3000 feet AGL. I can see no reason to drag feet on this recommendation, other than the uncomfortable suggestion that perhaps this issue should have been addressed during certification. (It is yet another difference from older 737 design , like the deadly MCAS system, that was not disclosed to pilots transitioning to the new aircraft)

berkut

It's not clear that is does affect Airbus does it?

It looks like only the LEAP-1b engines are affected by this, and I was under the impression that LEAP-1b was 737-MAX-only?

(A320 has LEAP-1a as far as I can see).

unsnap_biceps

he covers this in the video, but both engines have the same LRD (Load reduction device), but it's more about how the bleed system is done on if it's an impact or not, and he doesn't know if the other planes have the same flaw or not.

hypothesis

I wonder what was the thought process there: hey we save an engine maybe, but everyone inside the plane gets cooked in 39 seconds. Ship it!

Comments on that youtube video are filled with industry insiders and it’s just wild. They even think someone has died from a similar fuming event back in December…

K0balt

It doesn’t save the engine, it keeps it from ripping the wing off. It’s a good system.

The part about filling the cabin with smoke because they couldn’t be bothered to make the software that detects the extreme vibration tell the AC units from that engine to shut down (which they already do if the rpm drops, indicating an engine failure-just not soon enough or reliable enough to prevent the smoke issue) - not so much.

The system for the ECU to detect the engine mount failure condition already exists. The function to shut down the air handlers in response to a different indicator of engine failure already exists in the ECU. It’s just literally “also shut down if the engine mounts fail”, but the guys that sit around and think about the what ifs were given early retirement to make room for more MBAs.

hypothesis

> It doesn’t save the engine, it keeps it from ripping the wing off. It’s a good system.

Sure, I get that it was added to prevent plane from disintegrating, but like you said integration thinking is gone and now we have those individual components that sure look homicidal from outside.

The other issue is that regulators are missing in action or worse. It’s no way to run the industry by relying on concerned youtubers..

K0balt

I’m with you on all of this. It’s like all of the grownups left the building and the inmates are running the asylum.

Frikken clown world hijinks.

cduzz

Not cooked -- poisoned.

As far as I understand, the people in the cabin or the cockpit will breath the oil that's now been aerosolized -- in the cockpit it's really hazardous because it's such a small air volume. The oil's full of all kinds of things you wouldn't ever want to breathe in, and in the cockpit it's enough to poison you really fast.

Havoc

Maybe they were thinking the Russian solution. If it crashes fast enough nobody finds out what happened

xeonmc

Could this also have been activated in the Jeju air crash from the initial bird strike?

unsnap_biceps

According to wikipedia, https://en.wikipedia.org/wiki/Jeju_Air_Flight_2216#Aircraft , Jeju was running different engines then listed in the video as impacted.

berkut

No, that aircraft was a 737-800 (NG), whereas the LRD is only on the LEAP engines of the 737 MAX...

alistairSH

IIRC, that was a 737-800 not a 737 MAX 8.

exabrial

[flagged]

nottorp

No, it's because they blamed an undocumented system that killed two plane loads of people on pilot error...

Also because later they were caught forgetting to screw down things... see that lost door.

There's about zero trust in Boeing.

wobfan

> No, it's because they blamed an undocumented system that killed two plane loads of people on pilot error...

And kept hiding and sabotaging the court process against them to hide that they and their pilots knew, even before the first crash, that this might happen. Like, I don't think Russia or anyone else did even have to do anything at all here, if they would've had any reason to. Boeing fucked up themselves.

greggsy

Boeing has been in the media for a variety of corporate misconduct reasons, and the court cases were held in the US, which attracts the attention of the American media, which is a self-amplifying echo chamber which global consequences.

I don’t doubt there were similar Airbus cases, but to suggest that the redirected attention is wholly due to an interference campaign is a bit far fetched in my opinion.

sho_hn

These are the most comparable times in the history of Airbus:

https://admiralcloudberg.medium.com/one-hundred-seconds-of-c...

https://admiralcloudberg.medium.com/thinking-like-a-computer...

Unlike with Boeing they didn't feature intentional obfuscation and fraud, but very similar themes of the airplane's software model of what's going on diverging from the pilots' and resulting in disaster.

Along with stories like the Therac-25, this is one of my "favorite" engineering stories relevant to my profession.

Sakos

From the article:

> Although it got off to a rocky start, the A320 went on to achieve a better safety record than most traditional aircraft types. And although there have been a couple of close calls, no Airbus has ever crashed because of the sort of computer failure that skeptics so deeply feared.

Airbus didn't just fight the need to improve their designs. They just kept improving on their designs and fixed what needed to be fixed.

I'm not sure why Boeing and Airbus are being treated equivalently by you and the other commenter. Especially since the two situations are nothing alike. Boeing hid MCAS to avoid a new type rating. The Airbus A320 just had new types of systems that would continue to be iterated on over time and were simply new.

kevin_thibedeau

Boeing has been fucking up continuously for 30 years. Airbus, not so much.

Sakos

This is still being investigated. It also doesn't seem to be a widespread and common issue requiring the full brunt of internet outrage. I'm beginning to wonder if you're arguing in good faith.

You realize that the difference between this incidence and the one in this HN post is that the FAA made a recommendation in a report (IN 2023) for how to resolve the smoke issue, and it still hasn't been implemented by Boeing? That couldn't be the issue, it must be a conspiracy.