Southwest Airlines engine failure.

[schmitt trigger]

Whenever I read about an accident similar to Southwest Airlines flight 1380, in addition to feeling the pain for the victim's grieving friends and families, I also feel the pain of the engineers and investigators tasked with finding the root cause or causes for the accident.

The pressure on them is beyond incredible. Grueling hours, pressure from every corner.
Fortunately I've never had a job whose product's failure causes an immediate life-threatening situation. Still a failure from some of our products can still cause significant body harm and economic damage.
We once had where a single MLCC capacitor, which suffered a flex crack. The capacitor was filtering a sensor's analog output voltage, causing a  machine malfunction which injured an operator.
It took us almost a full year of non-stop work to clear that one.

Without giving away any details, as this may have legal ramifications, have you ever been involved in a similar situation?

[GreyWoolfe]

Thankfully, no.  Not much life threatening about fixing computers, printers, camera systems and such.

[Ampera]

In that case, don't become a car mechanic.

[Mr. Scram]

Whenever I read about an accident similar to Southwest Airlines flight 1380, in addition to feeling the pain for the victim's grieving friends and families, I also feel the pain of the engineers and investigators tasked with finding the root cause or causes for the accident.

The pressure on them is beyond incredible. Grueling hours, pressure from every corner.
Fortunately I've never had a job whose product's failure causes an immediate life-threatening situation. Still a failure from some of our products can still cause significant body harm and economic damage.
We once had where a single MLCC capacitor, which suffered a flex crack. The capacitor was filtering a sensor's analog output voltage, causing a  machine malfunction which injured an operator.
It took us almost a full year of non-stop work to clear that one.

Without giving away any details, as this may have legal ramifications, have you ever been involved in a similar situation?

How can any business afford to work a year for free? I assume you're not saying that the entire company did this, but it sill sounds like a large investment.

[CatalinaWOW]

It is incredibly difficult when you think your product is involved in a loss of life situation.  I have twice been in that situation.  In one case the investigation showed the cause was elsewhere, even though our product was the initial suspect.  In the other case our analysis discovered the potential for a lethal accident.  The resulting phone call to customers requesting that they discontinue use of our product until the matter was resolved was nearly as bad.  The product was important to them, and it was just good fortune that the lethal condition had not yet occurred.

[SparkyFX]

Fortunately I've never had a job whose product's failure causes an immediate life-threatening situation.

I work in such an area on a daily basis. The biggest risk to the product is management.
Of all Bullshit Artists i´ve met, most were cautious enough to not document what they want (as that would outright document their gross negligience), but as usual the bigger idiot with the more unrealistic plans or excessive promise to get that job is just around the corner. The only thing in their way are people that actually know what they are talking about, but they are en route to solve that problem too, by creating a real downward spiral to all applicable standards.

I have a relative in the aviation maintenance business, they have a lot more safety procedures to follow, better documentation, higher education standards and therefore less of such problems.

[G7PSK]

Just been watching this, his closing comments made me think about what was being said about autonomous cars on this forum and how they were going to be superior than humans.

[schmitt trigger]

How can any business afford to work a year for free? I assume you're not saying that the entire company did this, but it sill sounds like a large investment.

No.
I wasn't saying that we worked for free.
I was saying that I was involved on a task group which did almost anything else but to work on this particular problem; finding its root cause, creating a robust containment action, and validating a corrective action.

[floobydust]

MOSFET shorted. VN10K's are extremely fragile with ESD. So the natural gas solenoid stayed on and filled the system with gas 
After a couple explosions, management did- not much  It's the usual - blame the customer, blame the vendor, blame manufacturing, blame the design etc. etc.
Not my design, but a single component failure caused big trouble.

No different than a turbine blade this CFM 56-7B engine.

There was once a fatigue failure on a passenger jet engine and it was tracked down to used turbine blades being sold as new. Big money there.

[CopperCone]

[IanB]

With jet engines there is supposed to be containment. Since engines will throw a blade from time to time, the engine housing is supposed to contain the shrapnel. Engines are tested for this kind of failure on a test stand to see what damage results.

In this case it is very unfortunate that the containment did not work as expected. I am sure the investigators will be trying to understand why.

[james_s]

At least in this case the plane returned safely and landed with the damaged engine relatively intact. That makes the investigation a whole lot easier than when they have to sift through piles of shredded debris in search of the culprit.

[Neomys Sapiens]

The point about turbofan uncontained blade failures is such, that the engine is not expected to contain the worst case failure, which is a large, continous piece coming off at high rpm. The usual line of thought is that of those failures, a large proportion will be detected and avoided again. So the remainder, which is a large, fast piece of blade coming off and moving towards the passenger-carrying part of the fuselage is treated as 'that is the reason why aviation insurance is expensive. Stop worrying.'
I don't like commercial flying much. If I must, I take a window seat. Most blades stay where they belong. Period.
I would not like to see this happen on the latest product of this airplane manufacturer. I try not to board it at all.

[Homer J Simpson]

I thought part of the certification for an engine was it had to be able to contain a blade failure?

-k

[Homer J Simpson]

Just googled my own answer.

From Wikipedia........

Contained and uncontained failures

Engine failures may be described as "contained" or "uncontained". A contained engine failure is one in which components might separate inside the engine but either remain within the engine's cases or exit the engine through the tail pipe. An uncontained engine failure is more serious because pieces often exit the sides of the engine, posing potential danger to the aircraft structure and those within the plane. Although engine manufacturers are required by the FAA to perform blade off tests to ensure containment of shrapnel if blade separation occurs,[7] the National Transportation Safety Board notes that "Engine enclosures are not designed to contain broken turbines, rather the turbines are designed not to break."[8]

[Mr. Scram]

No.
I wasn't saying that we worked for free.
I was saying that I was involved on a task group which did almost anything else but to work on this particular problem; finding its root cause, creating a robust containment action, and validating a corrective action.

Did this yield the company profit?

[IanB]

Just googled my own answer.

From Wikipedia........

Contained and uncontained failures

Engine failures may be described as "contained" or "uncontained". A contained engine failure is one in which components might separate inside the engine but either remain within the engine's cases or exit the engine through the tail pipe. An uncontained engine failure is more serious because pieces often exit the sides of the engine, posing potential danger to the aircraft structure and those within the plane. Although engine manufacturers are required by the FAA to perform blade off tests to ensure containment of shrapnel if blade separation occurs,[7] the National Transportation Safety Board notes that "Engine enclosures are not designed to contain broken turbines, rather the turbines are designed not to break."[8]

Although the pictures of the aircraft on the ground did seem to show a missing fan blade at the front of the engine, which would explain why the front cowling was shredded. (Turbofan engines have three sections: the fan at the front, the compressor in the middle, and the turbine at the back.)

[james_s]

There was definitely a missing fan blade, and you can see the abrasion around the fan casing. Given the location of the window that was broken, near the trailing edge of the wing it's quite possible that the shrapnel that broke it was not the fan blade but part of the cowling or inlet that was thrown free. There is a tremendous amount of kinetic energy involved. it's impossible to fully contain every possible type of failure under every circumstance. Even if nothing penetrates the engine casing the whole engine will flail and flex like crazy, shedding of external parts is almost inevitable.

It's just like the crumple zones and airbags in a car, they're designed to protect against most common collisions but they can't always succeed.

[radar_macgyver]

I thought part of the certification for an engine was it had to be able to contain a blade failure?

-k

Yup:

[G7PSK]

I thought part of the certification for an engine was it had to be able to contain a blade failure?

-k

I heard that the blade for whatever reason travelled forward before exiting the containment and that is why the cowling was shredded.   

[Gyro]

Hmmm, it looks as if they had an almost identical failure back in 2016. Same airline, same engine model, debris hit the fuselage causing cabin depressurization. The only difference is that it missed a window. It looks as if they have a problem with metal fatigue and are going to be enforcing more stringent testing.

http://www.bbc.co.uk/news/world-us-canada-43818752

Strange, CFM isn't a name I've heard of before, a bit surprising as it sounds as if they're in most 737s (8000 worldwide).

[Red Squirrel]

Incidents like this just come to show "shit happens".   One thing we need to remember is how rare this is and despite all the brains that go into it, sometimes things can still go wrong.  It's sad when people die but sometimes we just have to accept that things can go wrong.  Or course we can't dismiss it either, hopefully they figure out what happens.  I can't imagine the pressure that must be though.

[Maxlor]

I doubt the investigators are under very much pressure. Fortunately, the safety culture in aviation is such that the quality of the result of their investigation is valued much more highly than the speed with which they deliver it. So some very smart people will conduct their investigation, taking as much time to analyze everything as is required, and in the end write up a report that is comprehensive. They won't let their work be affected by pressure or stress.

[Rerouter]

Its the little unexpected things that always get you, My own one was, for a model of truck we had hooked into a bodybuilder canbus, well 2 things I learned about what happens when a OEM diagnostic computer is plugged in for a firmware update, 1. The data sent both ways is presented on that bus, and 2. the bodybuilder bus does not rebroadcast the "quiet" command that most tools transmit to tell all devices its king of the hill. resulting in 13 bricked ECU's... yeah that was a fun day.

As for the plane, the fan is missing, the cowling is damaged, so we can safely say "shit hit the fan" probably post incident, and some result of that hit the window, with enough kinetic energy to damage atleast 2 layers.

[james_s]

Strange, CFM isn't a name I've heard of before, a bit surprising as it sounds as if they're in most 737s (8000 worldwide).

CFM is one of the biggest names in turbine engines in the world. The 737 is the most widely sold airliner in history and they have been powered exclusively by the CFM56 for decades, and the engine is used on many other aircraft.