SWA1380 - diversion to KPHL after engine event

[MarkerInbound]

2) We didn't have the option of choosing between Flaps 15 and any other Flap setting on our QRH in the One Engine Inoperative Landing Checklist. Does planning a Flaps 5 landing raise the question of legality in terms of crew training?

I'm just curious.

FAR 91.3, 121.557 and 559, 125.319 and 135.19 all state something similar to "In an emergency situation that requires immediate decision and action the pilot in command may take any action that he considers necessary under the circumstances. In such a case he may deviate from prescribed operations procedures and methods, weather minimums, and this chapter, to the extent required in the interests of safety."

So no matter what rules you are operating under, if you are around to talk about it what you did is ok.

[FiveGirlKit]

EASA issued AD 2018-0071 (https://ad.easa.europa.eu/ad/2018-0071) on 26 March 2018 following the first incident of loss of fan blade. It says:

Reason:
An occurrence was reported of fan blade failure on a CFM56-7B engine. The released fan blade was initially contained by the engine case, but there was subsequent uncontained forward release of debris and separation of the inlet cowl. Preliminary investigation determined that the fracture in the blade initiated from the fan blade dovetail.
This condition, if not detected and corrected, could lead to fan blade failure, possibly resulting in uncontained forward release of debris, with consequent damage to the engine and the aeroplane.
To address this potential unsafe condition, CFM International issued CFM56-7B SB No. 72-1019, later revised, and CFM56-7B SB No. 72-1024, providing inspection instructions.
For the reason described above, this AD requires a one-time inspection of certain fan blades, and, depending on findings, accomplishment of applicable corrective action(s).
This AD is considered an interim action and further AD action may follow.

It is interesting that the FAA have not yet issued an AD on the same subject, despite a Notice of proposed rulemaking (https://www.federalregister.gov/documents/2017/08/25/2017-17828/airworthiness-directives-cfm-international-sa-turbofan-engines) (NPRM) being issued covering the same issue on 25 August 2017.

Maybe they are now speeding up the AD process, as stated here (https://www.faa.gov/news/updates/?newsId=90105)

[Highway1]

In the video the speaker says the cabin altitude warning goes off at around 13,500'? Is that correct. My experience of Boeings is that the warning sounds at a cabin altitude of 10,000' and the masks will drop automatically at 13,500'. Is the B737 different?

737 cabin altitude warning is triggered at 10,000ft (+/- 1000).

The altitude pressure switch releases the passenger oxygen mask automatically when cabin altitude is at or above 14000 feet.

[CONSO]

Captain certainly was extremely calm but then her years in the cockpit of an F18 doing stuff like night carrier landings would mean that while this was not exactly a walk in the park it probably wasnt the most frightning experience of her career.


She may NOT have been carrier qualified which would infer combat ready- and at that time women were not allowed in combat roles. She WAS and instructor AND " agressor" pilot for training . .

[PukinDog]

And what's all this cr*p about misuse of oxygen masks by the passengers ? Maybe they didn't follow the precise design features for designed use, but they were more in danger from not opening their individual release valves by not giving the line a good tug, but does it matter how they breathed sufficient oxygen, did anyone die through lack of oxygen ?


Exactly, cr*p. IF they donned them over mouths only, the brain is automatically going to have them sucking it in through their mouths because thats where it knows the O2 they put the mask on to get is. I really doubt anyone with it over their mouths only was breathing through their nose only.

No, nobody died. Nobody incapacitated either by any account. In fact, the 2 male pax who pulled the lady stuck halfway out the window and the female, ex-nurse pax who began attending to her once back inside doing CPR etc, plus whatever cabin crew were there on the injury scene did all they did do with no masks.

Those throwing spitballs about yellow-cup mask use as if it mattered just reckon they'd diligently follow every instruction to the letter under stress so they act as if those in the aircraft were wearing them on top of their heads like party hats, or something.

[CONSO]

Structurally-speaking, I wonder what kinds of tests Boeing will need to do around that window and fuselage area?EVER since the days of the British Comet disasters, there has been major attention to the structure around windows- There is a relatively ' massive' forging along and around the windows- window line. So much so that a few inches diff the part(s) would not have penetrated. No doubt that area will be NDT for any cracks or hidden damage.

[tscell7]

In the USA we "declare an emergency". However if lack of use of the word "MAYDAY" is the only criticism we can throw at this American domestic crew operating in American domestic airspace, let's just shut up and say good job.

I would concur. There was no confusion between pilot and controller. I listened to the audio and from the moment the pilot announced they were descending, the controller inferred the emergency and began vectoring them towards a landing.

My only quibble with the approach controller were the multiple queries about the nature of the emergency ("is the engine still on fire?" etc.) which were probably redundant in a situation where the pilots' hands were full.

I also found it interesting that the pilot chided ATC about too many frequency changes -- those were edited out of the audio clip I listened to.

[Herod]

IIRC, the use of "Pan" and "Mayday" in UK is also to cover against any claims by third parties. I once had a medical emergency on board and requested a priority landing. The controller advised that he couldn't give me that. "Pan, pan, pan"...."You are cleared direct three-mile final". That way, if anyone, e.g. people under a non-standard flight path, complain, the controller and the airport authority are covered. Different from America, and perhaps American pilots operating into UK should know about it. Thread drift; sorry.

[costalpilot]

I would concur. There was no confusion between pilot and controller. I listened to the audio and from the moment the pilot announced they were descending, the controller inferred the emergency and began vectoring them towards a landing.

My only quibble with the approach controller were the multiple queries about the nature of the emergency ("is the engine still on fire?" etc.) which were probably redundant in a situation where the pilots' hands were full.

I also found it interesting that the pilot chided ATC about too many frequency changes -- those were edited out of the audio clip I listened to.

quite right...imo, the emergency should have been given directed a discrete frequency. there were way too many distracting transmissions, so much so that at one point atc had to clarify to the emergency flight who they were talking to. .

Also. ATC ended up having to tell the emergency flight that some of ITS questions: 'it doesn't matter." Indeed, it didn't matter.

Approach control even instructed the emergency flight to avoid "the city" while giving her the mda.

I understand much of it (tension), but the frequency congestion was avoidable, had they just given her a discrete frequency. How hard could that be?

[Airbubba]

For some reason, I don't think Southwest pilots have to worry too much about ICAO R/T procedures.

[Ian W]

It can be seen that a minor amendment to the certification requirement may relieve the interference of multiple aural alerts expressed by "Good Business Sense"


"b. Multiple Aural Alerts
(1) Aural alerts should be prioritised so that only one aural alert is presented at a time. If more than one
aural alert needs to be presented at a time, each alert must be clearly distinguishable and intelligible by the flight
crew (CS 25.1322(a)(2)).
(2) When aural alerts are provided, an active aural alert should finish before another aural alert begins.
However, active aural alerts must be interrupted by alerts from higher urgency levels if the delay to annunciate the
higher-priority alert impacts the timely response of the flight crew (CS 25.1301(a)). If the condition that triggered the
interrupted alert is still active, that alert may be repeated once the higher-urgency alert is completed. If more than
one aural alert requires immediate awareness and the interrupted alert(s) affects the safe operation of the
aeroplane, an effective alternative means of presenting the alert to the flight crew must be provided to meet the
requirements of CS 25.1322(a)(1) and (a)(2)."

That sounds well and good for someone writing a spec. But now imagine you have several high urgency aural alerts. The effect is one continual stream of aural alerts and their visual counterparts just as your piloting skills are being tested by the failures the alerts are repeating to you. It is a human factors nightmare.
The aural sense is actually the first to be suppressed when under stress, so all the aural alerts may do is increase the stress to a level at which they are ineffective.

[SamYeager]

Sure, I listen to the brief.




There was mention on another forum that the oxygen from these masks tends to stink and that this might be a reason for the masks just covering the mouth. It was also mentioned that because FAs never place the mask physically on their face it can appear to passengers that it just needs to be put over the mouth.


For those that bother to read the emergency card it's obviously quite clear how the mask should be positioned but sadly we know that not everyone does that. Without personal experience I can't comment on whether or the oxygen smells and if so how much. Anyone have personal experience they can share?

[OldnGrounded]

>>> . . .whether or the oxygen smells. . .

The oxygen doesn't smell, but it is released from an "oxygen sponge" of (mostly) sodium chlorate in a chemical reaction that heats the NaCl03. The system creates a lot of heat (circa 250°C) in the overhead and things often smell like burning. . . things.

Google "chemical oxygen generator."

[PAXboy]

If you think the masks issue is being laboured in here, not it has reached mainstream Southwest Airlines emergency sparks on-board safety warnings - BBC News (http://www.bbc.co.uk/news/world-43823145)

You can be sure that no briefing is going to warn about the burning smell! Perhaps, during an emergency descent, when reassuring pax, the CC might explain WHY the sudden reduction in altitude and that any other smell you can detect = Don't Panic!

[clareprop]

If you think the masks issue is being laboured in here, not it has reached mainstream Southwest Airlines emergency sparks on-board safety warnings - BBC News

That article was posted earlier but has been deleted.

Edited to say that the biggest inaccuracy - about masks being useful in a fire has now been edited out of the BBC article.

[Concours77]

I would think that loss of a fan blade under these conditions would suggest a chaotic exit for the blade mass... I have no difficulty imagining the blade in any or all of several postures post separation from the disc. The dove tail (pine tree) would be susceptible to “rocking” in normal use, forward in Thrust, and backward in windmill. I doubt the dove tail failed evenly in an instant, it would be unlikely the joint let go evenly across its attachment joint. If the failure originated in the rear of the joint, the blade would immediately try to unpeel forward causing the tip to migrate well ahead of the fan’s plane, perhaps explaining the lack of evidence of major contact damage to the blades bracketing it?

Wouldn't the blade accelerate forward, rapidly, as a reaction to loss of attachment? (Newton #3)? Contacting the containing ring (likely it’s first point of contact) it would react violently to interruption of its linear escape, and likely start to wobble intensely? From the reasonably crisp remnants of the cowl, it looks like the blade lingered, radially, at least long enough to trim the honeycomb back to solid metal (Kevlar?).

It would be most interesting to see what remains of the disc pine tree? My conclusion is that the blade left the axis of the engine’s shaft rapidly, but retained some radial trail. How far forward of the engine’s inlet did it extend before traveling aft?

[WHBM]

There is now a rapid inspection regime. The CFM56 has been in volume production for some 35 years now, so I wonder why it is only now that an event which requires a campaign check has come to light.

Rubber jungle is not only accompanied by the smell from the oxygen generators. I've more than once seen pax describe to the media that the masks were "old and dusty". Nobody had explained that the "dust" is actually french chalk, which engineers pack them with to minimise any snagging on deployment.

[tdracer]

There is now a rapid inspection regime. The CFM56 has been in volume production for some 35 years now, so I wonder why it is only now that an event which requires a campaign check has come to light.
There are differences between the fans of the different marks of the CFM56 (the 737 NG is the -7, previous 737s were -3, the A320 is -5, and those used to re-engine KC-135s and DC-8s were the -2). Furthermore, according to one write-up, the event engine had 40,000 cycles, 10,000 since overhaul (I'm a bit suspicious - 40k cycles would be a huge amount - I wonder if that's hours not cycles). At any rate it's a very high time engine, so it seems likely that we're looking at a wear-out mode - which may be unique to the CFM56-7 model.
At any rate the FAA has some explaining to do regarding why it's been sitting on a planned fan blade inspection AD for 8 months...

[Thrust Augmentation]

No aviator or engineer (as will be obvious...), but the discussions on the trajectory of the errant blade & the differences between static testing & real world blade loss are quite interesting.

On a static test stand the engine will be consuming air that has a density of 1.22 Kg/M3, at FL320 its about 0.41 Kg/M3 - assuming that the engine consumes the same volume at the intake regardless of altitude, does density not play a part in the forces acting upon the fan & if it does would this not make a forward blade trajectory more likely at altitude as there is less mass of air forcing the blade rearwards?

If there is any truth in that, the fact that the static engine is operating in still air & the flying engine operating in a 400kn+ airflow must also play a part - possibly to the extent that it completely cancels the above idea & then some.

Please excuse if this is utter nonsense:ok:

[evansb]

Switch to a discrete frequency? ATC can't just invent a frequency. How about 121.5 mHz? You know, the International Distress Frequency? Perhaps the air traffic controller didn't even have that frequency at his/her disposal. "Silence, Mayday" could have been imposed, where all non-essential traffic shut up. Clearly these ideas have become obsolete.

[infrequentflyer789]

... If the failure originated in the rear of the joint, the blade would immediately try to unpeel forward causing the tip to migrate well ahead of the fan’s plane, perhaps explaining the lack of evidence of major contact damage to the blades bracketing it?
...


I believe in one of the NTSB briefings it was said that the crack was at the rear and would not have been possible to see on a visual inspection from the front (I think it was in Q&A and that was the question). At some point after separation we know the blade itself fractured into at least two pieces - because the NTSB have the root half but not the rest - but what caused that we can only guess. I doubt it was impact with the rest of the fan because (as you say) what we've seen shows surprisingly little damage there.

[Herod]

For some reason, I don't think Southwest pilots have to worry too much about ICAO R/T procedures.

Agreed, but I believe some American airlines do fly into the UK? I could be wrong, of course.

[BlankBox]

WTF!!!....frikken ambulance chasers at it already...

https://www.usatoday.com/story/news/nation/2018/04/19/southwest-passengers-could-collect-millions-after-deadly-ordeal/531537002/

:(

[Carbon Bootprint]

I believe in one of the NTSB briefings it was said that the crack was at the rear and would not have been possible to see on a visual inspection from the front (I think it was in Q&A and that was the question). Actually, what he said was that the crack was found to be in the interior of the blade. This was in Sumwalt's briefing yesterday afternoon (post 250), at about the 20:00 min mark. He rolled up a piece of paper and pointed inside the tube to show that it wasn't something that would be spotted in a simple visual inspection.

[ph-sbe]

Why did the Capt. not simply give a mayday call as it was most appropriate.

Because she felt it was not needed. If you listen to the ATC recordings, she stayed exactly within the limits of her authority without getting "trigger happy".

She initiated her descent and subsequently informed the controller (aviate, navigate, communicate). By doing that she used her authority provided by 14 CFR 91.3b, and exactly by that rule: she only deviated from her previous clearance to the extent necessary (emergency descent).

She then asked for directions to the nearest suitable airport. At that point, the controller was perfectly aware of the situation and there really was no need to explicitly declare an emergency.

But, even so: if needed a controller can "declare an emergency" for you. In reality it was not needed, since no rules needed to be breached. If, for example, she had to fly through restricted airspace to get to the runway, then explicitly declaring an emergency may have made sense. But even in that case: no FAA official is going to question her actions.

You declare an emergency to get the attention you need. If you already have the attention, it's just a waste of brain cycles and precious communication time.

[Matt48]

There are differences between the fans of the different marks of the CFM56 (the 737 NG is the -7, previous 737s were -3, the A320 is -5, and those used to re-engine KC-135s and DC-8s were the -2). Furthermore, according to one write-up, the event engine had 40,000 cycles, 10,000 since overhaul (I'm a bit suspicious - 40k cycles would be a huge amount - I wonder if that's hours not cycles). At any rate it's a very high time engine, so it seems likely that we're looking at a wear-out mode - which may be unique to the CFM56-7 model.
At any rate the FAA has some explaining to do regarding why it's been sitting on a planned fan blade inspection AD for 8 months...

It appears the fan blades can be removed from the disc without greatly dismantling the engine while on the wing, can the blades be crack checked this way.

[aterpster]

You declare an emergency to get the attention you need. If you already have the attention, it's just a waste of brain cycles and precious communication time.

Disagree. Two engine inop approach on 727 for example.

[tdracer]

It appears the fan blades can be removed from the disc without greatly dismantling the engine while on the wing, can the blades be crack checked this way.
Short answer is YES. There are some minor complications - for example you want to number the blades and put them all back in the exact same position (otherwise you'll foul up the fan balance), but the fan blades can be readily removed, inspected (probably eddy current), and replaced in a few hours.

[Matt48]

Thanks TDR. !

[lomapaseo]

In my view The questions about blade behavior are way too technical for this kind of thread. The same questions and faulted assumptions keep popping up on multiple posts.

The blades, behavior once it has separated is governed by Newtoian physics and not by aerodynamic forces which are pittance compared to the Newton laws of motion. So put the blade air loads out of your mind.

For the blade breakup into multiple large pieces, it's extremely plastic at these impact strain rates and column buckling is taking place. The forward motion is due to sliding friction of the blade tip once it strikes the case.

[RatherBeFlying]

Aerodynamics follows Newtonian principles, even at high Mach numbers.

[visibility3miles]

The story of the pilot who calmly landed the Southwest Airlines flight
‘She has nerves of steel’: The story of the pilot who calmly landed the Southwest Airlines flight

https://www.washingtonpost.com/local/trafficandcommuting/investigators-in-fatal-southwest-flight-want-to-know-why-engine-fan-fractured/2018/04/18/e1d72ddc-430a-11e8-bba2-0976a82b05a2_story.html?utm_term=.e7e5f8314cff

The pilot’s voice was calm yet focused as her plane descended, telling air traffic control she had “149 souls” on board and was carrying 21,000 pounds — or about five hours’ worth — of fuel.

“Southwest 1380, we’re single engine,” said Capt. Tammie Jo Shults, a former fighter pilot with the U.S. Navy. “We have part of the aircraft missing, so we’re going to need to slow down a bit.” She asked for medical personnel to meet her aircraft on the runway. “We’ve got injured passengers.”

“Injured passengers, okay, and is your airplane physically on fire?” asked the air traffic controller, according to audio of the interaction.

“No, it’s not on fire, but part of it’s missing,” Shults said, pausing for a moment. “They said there’s a hole, and, uh, someone went out.”...

...In the midst of the chaos, Shults deftly guided the plane onto the runway, touching down at 190 mph, saving the lives of 148 people aboard and averting a far worse catastrophe...

[Pugilistic Animus]

Not a 'Fighter Pilot' A Naval Aviator

[bpp]

Per my company Flight Operations Manual:

The phrase “declaring an emergency” no longer appears in FAA Pilot/Controller Glossary or the FAA 7110. The only method appearing in FAA or ICAO guidance is to declare a distress situation is the use of the word “Mayday” repeated three times. Pilots are cautioned that the use of the phrase “declaring an emergency” is not in compliance with regulatory guidance. (Nov 2017)

[ExSp33db1rd]

If you already have the attention, it's just a waste of brain cycles and precious communication time.

Agree - If there's nowt to say, don't say it.

Disagree. Two engine inop approach on 727 for example.

But it wasn't. Apples and Oranges.

[procede]

No aviator or engineer (as will be obvious...), but the discussions on the trajectory of the errant blade & the differences between static testing & real world blade loss are quite interesting.

I think the main issue is that the blade (due to being weakened by the fatigue crack) started to bend and rotate forward and did not break away clean to an explosion, like during the test. How many degrees it rotated forward before failing is something that needs to be analysed and might mean we need to rethink containment requirements.

[Dannyboy39]

Couple of things... the EASA AD not implemented by the FAA is a bit of a red herring. The effective date of that was only 2 weeks ago and operators have until 1st Jan 2019 to implement it, and it only affects certain PNs which may well change after the SB is embodied. I expect the FAA will now follow EASA’s lead but there’s nothing unusual about this situation. It does take time to inspect 15,000 7Bs globally operating 10 hours per day, which gives you some idea of its despatch reliability. Within that time probably a third of B737s would’ve been through C check which is an opportune time to carry it out.

Fan blades on the 7B also don’t have a finite scrap life (I believe only the Trent 700(?) is one of the few that does) and are replaced on condition after NDT/ultrasound/BSI findings.

If the engine is 10000 cycles since OH it probably is due a restoration soon, but that is nothing unusual (if SW operate 1.5 FH: 1 FC) You’d expect in the operating environment to double that and get up towards the limiter which is 20000.

[bsieker]

Short answer is YES. There are some minor complications - for example you want to number the blades and put them all back in the exact same position (otherwise you'll foul up the fan balance), but the fan blades can be readily removed, inspected (probably eddy current), and replaced in a few hours.

Reading the EASA AD (which is 3 weeks old, still a bit faster than the FAA), the prescribed inspection within 9 months of effective date of the AD is ultrasonic inspection according to an SB, but blades which have previously passed an eddy-current inspection according to the "Engine Shop Manual" are considered "serviceable", too.

I won't be surprised if the 9 month compliance period will very soon be shortened substantially through an EAD, at least for engines with a long service life.


Bernd

[bsieker]

Not an ATC or a pilot, but if someone tells me that half of their engines aren't working, and there's a hole in the plane large enough for someone to fall out out of it - I'm going to consider that an emergency, regardless of what precise terminology is or isn't used.

And nobody said it wasn't.

But regardless of whether or not that word (or the word "mayday") was used, the flight got all the attention required.

There's something to be said for internationally standardised phraseology, but in this case nothing important seemed to be amiss.


Bernd

[Less Hair]

If you just say "smoke" they will treat you like an emergency.
It's just a status that you need to divert from standard rules for a reason. If they know it they can assist you and clear the other traffic for you.

[wiggy]

Surely with damaged engine cowlings, descend as quickly as possible but perhaps not at Max speed?

I believe this got covered a page or two back...:ok:

Anyhow the Boeing Flight Crew Training Manual (FCTM) for a bigger Boeing twin is quite explicit in stating that in the event of a rapid descent you descend at a target speed of Mmo or Vmo unless structural damage is suspected, in which case “limit air speed and avoid high manoeuvring loads”...I suspect the 737 FCTM might contain similar comment....

[M.Mouse]

Surely with damaged engine cowlings, descend as quickly as possible but perhaps not at Max speed?

Assuming the B737 is like other Boeings the procedure for a Rapid Descent is to descend at VMO/MMO unless structural integrity is in doubt. How you determine structural integrity is an open question. I would suggest that if there is ANY doubt then limit airspeed.

Boeing tell us, I work as an instructor for Boeing in the UK, that with engine severe damage the vibration will be severe. It is not something we can replicate in the simulator because the amount of vibration would cause other problems apparently. We are assured that you will have no doubt that there is severe vibration!

During conversion and routine refresher training both Engine Severe Damage Separation and Depressurisation exercises are flown. Both events require prompt memory actions. What is unique(?) in this event was that both situations occurred either simultaneously or very close together. That puts a great onus on the crew to prioritise their actions which are made more difficult wearing an oxygen mask which, without doubt, makes communication between crew (sound of O2 through the intercom and restricted ability to look at your colleague directly, almost like wearing horse blinkers) more difficult.

It would have been a situation requiring excellent CRM in such a challenging situation.

It makes me cross in all the reporting that the reference is to 'the pilot'. Undoubtedly her co-pilot was an essential part of the operation to ensure a safe outcome.

With reference to the RT used it must be remembered that the USA has a slightly more laid back approach to RT than perhaps those of us in Europe. Listening to the transcripts there seemed to be no doubt that the seriousness of the situation was understood by all concerned. Had the crew thought otherwise they probably would have broadcast a Mayday call. Certain parts of the world I would say it would be essential!

Well done to all involved.

[Smilin_Ed]

"Fighter Pilot" is a subset of Naval Aviator.

[Mark in CA]

Posted in today's NY Times:

To the Editor:

Re “Quiet Flight, Then a Blast and a Sudden Plunge” (front page, April 19):

Capt. Tammie Jo Shults, a former Navy pilot, did an outstanding job flying Southwest Airlines Flight 1380 to safety on Tuesday, but readers should know that all airline pilots train for these emergencies. Demonstrating the ability to fly with an engine failure is required for airline transport pilot certification.

Also, quick drops, although scary, do not mean a crash is inevitable. Planes that lose cabin pressure as Flight 1380 did must descend quickly to an altitude where people can breathe unassisted.

Finally, though Captain Shults has been rightly lauded, the co-pilot, Darren Ellisor, also deserves praise for his skill under pressure. Crews act as teams during emergencies. The co-pilot reads checklists, acts as a second set of hands and talks with air traffic control.

Flying is the safest method of transportation today. We shouldn’t take for granted the many people who make it so.

MARY CATHERINE LONGSHORE
JUPITER, FLA.

The writer is a licensed commercial pilot.

[judge11]

Many moons ago, I, like many other readers of these fora, I am sure, had to learn swathes of the JSP 318. For our non-military and overseas friends, JSP 318 was the RAF's 'Miitary Flying Regulations'.

Of course, it was laden with definitions including those of PAN and MAYDAY, the definitions of both I shall undoubtedly carry with me to the grave.

MAYDAY - 'an aircraft is threatened with serious or imminent danger and is in need of immediate assistance'.

I would suggest that the flight in this scenario fitted the bill to the letter and a MAYDAY, irrespective of your location around the globe, would be an unambiguous call to make.

[hoss183]

Short answer is YES. There are some minor complications - for example you want to number the blades and put them all back in the exact same position (otherwise you'll foul up the fan balance), but the fan blades can be readily removed, inspected (probably eddy current), and replaced in a few hours.

In fact its even more clever than that. When visiting BAs maintenance facility, i was shown what the do on a/c during a C check.
The blades are taken out and inspected an weighed, thats fed into a computer and it defines the optimal position for each blade being put back to achieve the best balance.

[bsieker]

In fact its even more clever than that. When visiting BAs maintenance facility, i was shown what the do on a/c during a C check.
The blades are taken out and inspected an weighed, thats fed into a computer and it defines the optimal position for each blade being put back to achieve the best balance.

The most important data the computer needs to know about each blade is not its weight, but its moment of inertia relative to the rotor axis, but to make a machine for that is straightforward.

And the proposed rulemaking concerning CFM56-7B fan blades (referenced here earlier) should give you an idea how quick and easy it is to inspect the blades. The estimated cost for the operator is a mere $170 per engine (2 work hours), which is nothing in aviation.

And I would assume that when you do these inspections, the easiest way is in fact to just number the blades and their position on the disk with a permanent felt-tip marker.


Bernd

[whitav8r]

I just noticed this phrase on another article about this possible EAD for engine blade check and realized that the airlines must keep track of cycles for each blade!

“The industry took no major issue with the 2017 proposal, though some airlines requested longer compliance times. They said the rule would affect more than 220 engines because airlines often swap blades between engines.“

I assume this is done to better balance the disk?

Also, what are the statistics on blades that have been found to have a discovered failure during a check? How many cycles did they have on them?

And finally, CFM and/or Boeing better get busy on some sort of analysis (simulation) on how these blade fragments go forward of the "containment ring".

[KenV]

"Fighter Pilot" is a subset of Naval Aviator.Is it? Lots of USAF, RAF, IAF, Russia AF, etc etc folks are "fighter pilots." How many are Naval Aviators?

[G0ULI]

And I would assume that when you do these inspections, the easiest way is in fact to just number the blades and their position on the disk with a permanent felt-tip marker.

Bernd

The Chlorine based ink used in permanent markers reacts with Titanium, the main component in modern fan blades. This has the potential to be the initiating point for a stress fracture site. The law of unintended consequences?

It is rather ironic that innocent actions during the maintenance and inspections designed to detect and prevent fan blade failure could actually be responsible for some recent failures.

[Ian W]

Because she felt it was not needed. If you listen to the ATC recordings, she stayed exactly within the limits of her authority without getting "trigger happy".

She initiated her descent and subsequently informed the controller (aviate, navigate, communicate). By doing that she used her authority provided by 14 CFR 91.3b, and exactly by that rule: she only deviated from her previous clearance to the extent necessary (emergency descent).

She then asked for directions to the nearest suitable airport. At that point, the controller was perfectly aware of the situation and there really was no need to explicitly declare an emergency.

But, even so: if needed a controller can "declare an emergency" for you. In reality it was not needed, since no rules needed to be breached. If, for example, she had to fly through restricted airspace to get to the runway, then explicitly declaring an emergency may have made sense. But even in that case: no FAA official is going to question her actions.

You declare an emergency to get the attention you need. If you already have the attention, it's just a waste of brain cycles and precious communication time.

Oh but there is a reason to declare an emergency and even more importantly squawk 7700. You may be happy that the controller you are speaking to understands the problem but you have just gone into a crash descent into another controller's sector perhaps crossing through several. Squawk 7700 takes no time to select and EVERYONE in ATC for several hundred miles definitely all the controllers in New York and DC centers and associated TRACONs know about it as a 7700 squawk does not get filtered by the system. That will mean that aircraft that you WILL be conflicting with will be turned out of your way by their controllers without the controller you are speaking to - who does not have authority for the airspace you have descended into - having to add multiple ground line calls to her/his workload. It will also mean that before even being contacted PHL will have seen a 7700 aircraft coming their way. It really smooths the path for you in the ground systems.

Sure follow the mantra Aviate Navigate - but you are in one of the busiest airspaces in the CONUS - if you do not communicate you may add TCAS RAs and worst case a collision to your bad day. A simple 7700 solves all of that and tells everyone that you have a problem.

For those of you that care, current ATC systems will maintain your identity but add symbology that shows you have an emergency on controller displays.

7700 is the same for MAYDAY or PAN so it removes the dialectic nuances of is it really a MAYDAY or only a PAN and with modern surveillance systems is far more effective than an R/T call.

[KenV]

Aerodynamics follows Newtonian principles, even at high Mach numbers.OK. Let's try this: the Newtonian physics associated with the air acting on a separated fan blade are completely overwhelmed by the Newtonian physics of the moments of inertia acting on the blade. Kinda like a bullet in air-to-air combat. Sure, aerodynamics will affect the bullet's ballistic trajectory. But those affects are overwhelmed by the moments of inertia acting on the bullet.

I think the main issue is that the blade (due to being weakened by the fatigue crack) started to bend and rotate forward and did not break away clean to an explosion, like during the test. How many degrees it rotated forward before failing is something that needs to be analysed and might mean we need to rethink containment requirements. Two points:

1. A fan blade that "rotates forward" will almost immediately result in a blade tip/case strike. The resulting forces acting on the blade will cause the blade to fail at the fatigue crack.

2. What would cause the fan blade to "rotate forward"? The fan is a compressor section. In other words, in a turbo fan engine the fan blade compresses the air, it does not accelerate the air like a propeller. Further, the huge tension forces resulting from the massive centripetal acceleration of the blade will overwhelm any aero force pushing on the blade. Consider a guitar string. It is under considerable tension. Can you blow on the string to cause it to bend? No. The tension on the fan blade is several orders of magnitude greater than the tension on the guitar string.

[DaveReidUK]

OK. Let's try this: the Newtonian physics associated with the air acting on a separated fan blade are completely overwhelmed by the Newtonian physics of the moments of inertia acting on the blade. Kinda like a bullet in air-to-air combat. Sure, aerodynamics will affect the bullet's ballistic trajectory. But those affects are overwhelmed by the moments of inertia acting on the bullet.

Nice explanation, although I suspect you mean simply inertia, rather than moment of inertia, particularly in your ballistic analogy.

[Carbon Bootprint]

7700 is the same for MAYDAY or PAN so it removes the dialectic nuances of is it really a MAYDAY or only a PAN and with modern surveillance systems is far more effective than an R/T call.No argument, but I haven't seen or heard in any of the briefings or comms references as to whether SW1380 squawked 7700 or not. Does anyone know? Isn't it a checklist item for an emergency descent along with some of the other things that were going on here?

[highflyer40]

Listening to the tapes. All she said was she was single engine and descending. No mention of an emergency descent due to decompression. From what she said I would assume the controller would assume a gentle descent down to single engine ceiling.

[hoss183]

The most important data the computer needs to know about each blade is not its weight, but its moment of inertia relative to the rotor axis,

And I would assume that when you do these inspections, the easiest way is in fact to just number the blades and their position on the disk with a permanent felt-tip marker.

Bernd

Yes i should have expanded 'weighed', they were checking the CofG or balance on a machine.
In fact each blade has a serial number and each position on the rotor is numbered, thats how it was tracked.

[gums]

Nice explanation, Ken, and I agree with Dave about the trajectory analogy. Once that projectile leaves the barrel it doesn't make any difference what body rates and such were.

OTOH, Dave, I think the moments are very important as to where the blade breaks, especially if the density of the thing changes as you go from hub to tip.

Glad to hear that inspections are not as big a deal as I thot. NDI gear and procedures have changed dramatically since I got outta the business, just like medical equipment.

Gums..

P.S. I had severe fan blade destruction one day on my PW F100 after a chunk off ice came off the intake soon after takeoff. Had 60 -70 blades severely bent and many with large sections missing. Good thing about fans is a lotta debris goes around the core and only really big pieces leave "containment" We saw that with the TF-41 in the Sluf, as well, with bird strikes.

[KenV]

Nice explanation, although I suspect you mean simply inertia, rather than moment of inertia, particularly in your ballistic analogy.Well, it depends on your frame of reference. Since the blade is attached to the hub and the hub is spinning at a high rate, I used the term moment of inertia. Further, in my bullet analogy, a bullet is spinning at a very high rate which stabilizes it. Nevertheless, once the blade fails and detaches from the hub, the blade is behaving under plain inertia, and with no spin to stabilize it. So in that sense, you are correct and I concede your point.

[guadaMB]

There's something that puzzles me.
All over the Planet Earth it's being mentioned Mrs. Tammie Jo Shults as "the hero pilot, bla, bla,bla".
But listening to the radio exchange (brief and complete ones) between ATCs, TWR & AC, there's one thing very clear: THE PIC DURING ALL THE DESCENT WAS F.O. Mr. Darren Ellisor.
Mrs. Shults was in charge of radio and -surely- checklists while Mr. Ellisor was PIC descending and later aligning for a visual long final.
I've got not clear if Mr. Ellisor was PIC at the moment of the engine failure.

[Super VC-10]

It doesn't matter, both crew worked together as a team.

[Bergerie1]

guada,

It doesn't matter who was the handling pilot at the time of the incident. But good cockpit management (CRM) suggests that the captain should manage the situation while the copilot handles the aircraft. This allows the captain to have time to think, generally oversee the whole operation, do the R/T and run the checklists.

From what I heard of the ATC tape that is what seems to have happened. As to who does what and when, that is solely up to the captain - who remains in control of the whole conduct of the flight.

It appears to have been a good job very well done. Not hero stuff, but good professional competence.

[Concours77]

In fact its even more clever than that. When visiting BAs maintenance facility, i was shown what the do on a/c during a C check.
The blades are taken out and inspected an weighed, thats fed into a computer and it defines the optimal position for each blade being put back to achieve the best balance.

The procedure for removal of each blade involves sliding the blade root out of its disc mate. Loose enough to slide means play. Play means wear, likely unique to each paired joint.

I’d question the advisability of changing matched pairs in the interest of balancing the disc?

[hans brinker]

There's something that puzzles me.
All over the Planet Earth it's being mentioned Mrs. Tammie Jo Shults as "the hero pilot, bla, bla,bla".
But listening to the radio exchange (brief and complete ones) between ATCs, TWR & AC, there's one thing very clear: THE PIC DURING ALL THE DESCENT WAS F.O. Mr. Darren Ellisor.
Mrs. Shults was in charge of radio and -surely- checklists while Mr. Ellisor was PIC descending and later aligning for a visual long final.
I've got not clear if Mr. Ellisor was PIC at the moment of the engine failure.

No, at no point in time was Ellisor PIC. I believe he was PF for most of the event, until Shults took the controls for the landing. That doesn’t change the fact Shults was the PIC for the whole flight.

[tdracer]

“The industry took no major issue with the 2017 proposal, though some airlines requested longer compliance times. They said the rule would affect more than 220 engines because airlines often swap blades between engines.“
Fan blades are often removed to repair minor damage (bird strike, FOD, etc.) - this is likely more common on 737/CFM56 due to the low inlet on the 737 and the relatively high number of cycles the engines see relative to wide body aircraft. How this is done is operator specific - some change blades as an engine set, some replace the damaged blade(s) along with the blade 180 deg. opposite with a matched blade to retain fan balance, still others will only replace the damaged blade(s) then do a fan balance run.
Fan balance is very important for the CFM56 on the 737 - the engine is so close coupled with the wing that any fan imbalance will cause annoyingly high vibrations in the passenger cabin.
But the main point is that if an operator has 10 engines that would be affected by the AD, the fan blades originally from those engines might be spread around many more than 10 engines.
<edited to address Concours 77>
While there will always be a small amount of wear between the blade dovetail and the hub, special coatings and lubes are used to limit the wear, and there are strict limits on the allowable amount of wear (it's not much - a few thousands).

However, having been involved in several FAA AD's over the years, 8 months and it's still not released is inexcusable. AD's by definition affect flight safety. Normal flow time for a 'routine' AD is a couple months - seldom going much beyond 3 months even if there are lots of comments (emergency AD's don't go through public comment and can go out in a few days). While getting the blade inspection AD released may not have affected this accident, it's pretty clear to me that someone in the FAA dropped the ball.

[lomapaseo]

However, having been involved in several FAA AD's over the years, 8 months and it's still not released is inexcusable. AD's by definition affect flight safety. Normal flow time for a 'routine' AD is a couple months - seldom going much beyond 3 months even if there are lots of comments (emergency AD's don't go through public comment and can go out in a few days). While getting the blade inspection AD released may not have affected this accident, it's pretty clear to me that someone in the FAA dropped the ball.

Well of course hindsight is much clearer than foresight.

However both the manufacturer and the FAA have processes developed under continued airworthiness rules to assess in-service experience coupled with today's analysis. Such experience includes probable causes and population at risk, (of a blade fracture) certification basis, and any unexpected in-service additional safety concerns beyond a safe engine shutdown.

The risk analysis does consider a given that a blade fracture will occur sometime in the future, but given such a fracture other combinations of risk in the in-service experience ala crew error or parts being liberated beyond the engine itself (possibly some others that I can't remember at this time)

In the end such analysis need show that the risk of a far more serious event than currently experience in the data must be extremely low and not significantly contribute to the underlying risk of flying that product in its expected lifetime.

It does not mean that a simple blade fracture will not occur while they are dotting the "Is" and crossing the "Ts" in a proposed AD but based on data available nobody close to this would have expected the result in this flight.

OK it is obvious that an unexpected combination did occur and the AD does have to be adjusted. So let's just get after this bottom line lest we end up only blaming somebody instead.

[Highway1]

I’d question the advisability of changing matched pairs in the interest of balancing the disc?

Standard practice on the 737

https://www.pprune.org/members/475048-highway1-albums-pics-picture1153-screenshot-2018-04-20-13-43-46.png

[tdracer]

However both the manufacturer and the FAA have processes developed under continued airworthiness rules to assess in-service experience coupled with today's analysis. Such experience includes probable causes and population at risk, (of a blade fracture) certification basis, and any unexpected in-service additional safety concerns beyond a safe engine shutdown.


Loma, not disagreeing with anything you wrote, but it's also true that the FAA has established flow times - and those flow times would not have allowed an AD to languish for anywhere near 8 months and not be released (an FAA spokesperson has basically admitted as much).
Think of it this way - the risk assessment said they could allow 12 months to do the inspections without a significant safety threat - but they'd already used up over half of that and still hadn't mandated the inspections. So the safety assessment would have to be for at least 20 months which would most likely change the answer.
Knowing and having worked with the FAA for 2/3rds of my career, I'd bet pretty good money the AD's been sitting in someone's in-basket - forgotten - for several months. I'd bet even more money that the responsible person or persons will get nothing worse than a wrist slap.

[CONSO]

Airline Regulators Call for Emergency Inspections of Boeing 737 Engines

Regulators expected to require inspections sooner, and of more engines, than previously proposed



https://www.wsj.com/articles/airline-regulators-call-for-emergency-inspections-of-boeing-737-engines-1524255154

By Andy Pasztor, Doug Cameron and Robert Wall

Updated April 20, 2018 4:17 p.m. ET 0 COMMENTS (https://www.wsj.com/articles/airline-regulators-call-for-emergency-inspections-of-boeing-737-engines-1524255154#comments_sector)


U.S. aviation regulators in the wake of this week’s fatal Southwest Airlines Co. accident (https://www.wsj.com/articles/southwest-jet-makes-emergency-landing-in-philadelphia-1523985825) are expected as soon as today to impose emergency inspection requirements for certain jet engines going beyond what they previously proposed, according to people familiar with the issue.

[Vessbot]

2. What would cause the fan blade to "rotate forward"? The fan is a compressor section. In other words, in a turbo fan engine the fan blade compresses the air, it does not accelerate the air like a propeller.

There is no substantial difference between an axial compressor, fan, and propeller. They all apply a rearward force on air, and therefore the air applies a forward force on the blade.


Further, the huge tension forces resulting from the massive centripetal acceleration of the blade will overwhelm any aero force pushing on the blade.

You've repeated this a few times, but never with any subtantiating argument. An intuitive appeal to the tension on a guitar string vs. the force of air blowing out of one's mouth, is naive and unconvincing.

[lomapaseo]

There is no substantial difference between an axial compressor, fan, and propeller. They all apply a rearward force on air, and therefore the air applies a forward force on the blade.

Agree until such time that it stops rotating about the eng drive shaft and moves purely in translation with some rotation about it's own CG thus altering the incident angle on the blade with the air. Then 5 milliseconds later it develops significant friction against the outer fan case structure and is guided by these forces at the tip which far outweigh any aero forces by many factors.

[PastTense]

Knowing and having worked with the FAA for 2/3rds of my career, I'd bet pretty good money the AD's been sitting in someone's in-basket - forgotten - for several months. I'd bet even more money that the responsible person or persons will get nothing worse than a wrist slap.

Perhaps, but it also could be a result of the current administration's deregulation initiatives.

[slfool]

According to the NTSB press conference the blade broke in two places, near the root and further up. They have the section nearest the root, they don't have the outboard section. Doesn't that suggest that the section of blade nearest the root went backwards into the engine? If the speculation about the blade shooting forward and clear of the engine was correct, it seems almost certain they wouldn't have either section.

[lomapaseo]

tdracer

However, having been involved in several FAA AD's over the years, 8 months and it's still not released is inexcusable. AD's by definition affect flight safety. Normal flow time for a 'routine' AD is a couple months - seldom going much beyond 3 months even if there are lots of comments (emergency AD's don't go through public comment and can go out in a few days). While getting the blade inspection AD released may not have affected this accident, it's pretty clear to me that someone in the FAA dropped the ball.

A lot to agree on above, except what office issues the AD and under what supporting arguments? After all the engine was safely shut down according to it's certificate. It's only in conjunction with the design of the aircraft certification that it progressed or might have progressed to an unsafe result. If it was an FAA guy in the engine section writing the words in the AD he might have gotten a lot of push back by the operators about the assumptions and had to go back to both Boeing and GE to substantiate responses to comments.

I predict that this will all come out in a public hearing chaired by the NTSB

he who breaks the crockery must pick up the pieces

[slfool]

Large Engine Uncontained Debris Analysis
DOT/FAA/AR-99/11
http://www.tc.faa.gov/its/worldpac/techrpt/AR99-11.pdf

Section 4.1.2, page 38 onwards

In a typical fan blade failure event where a large (> 50%) section of the blade is released, the blade tip section fragments and slides forward resulting in a helical trajectory while the root section of the blade is caught by the trailing blade and swept aft.

Much more information besides...

[costalpilot]

There's something that puzzles me.
All over the Planet Earth it's being mentioned Mrs. Tammie Jo Shults as "the hero pilot, bla, bla,bla".
But listening to the radio exchange (brief and complete ones) between ATCs, TWR & AC, there's one thing very clear: THE PIC DURING ALL THE DESCENT WAS F.O. Mr. Darren Ellisor.
Mrs. Shults was in charge of radio and -surely- checklists while Mr. Ellisor was PIC descending and later aligning for a visual long final.
I've got not clear if Mr. Ellisor was PIC at the moment of the engine failure.


I'm not clear about anything you assert.

The PIC signs the release and is the PIC for the entire flight . Also there is a PF and PNF. As to who flies, that is determined by the PIC for the entire flight.
Who talks on the radio depends on the situation and is, alas, also determined by the PIC. It could be anybody. It could be the jumpseater.

(Pilot In Command)

That is the way it was done where I come from----back in the day.

Is it done differently anywhere?

[AmericanFlyer]

https://www.reuters.com/article/us-pennsylvania-airplane/u-s-regulator-to-order-jet-engines-inspection-after-southwest-explosion-idUSKBN1HO2K4

[climber314]

The new EAD is signed as follows:

Original signed by
Karen M. Grant, Acting Manager
Engine and Propeller Standards Branch,
Aircraft Certification Service.

Does this mean the previous "manager" has been sacked for not doing his/her job?

[VinRouge]

OK. Let's try this: the Newtonian physics associated with the air acting on a separated fan blade are completely overwhelmed by the Newtonian physics of the moments of inertia acting on the blade. Kinda like a bullet in air-to-air combat. Sure, aerodynamics will affect the bullet's ballistic trajectory. But those affects are overwhelmed by the moments of inertia acting on the bullet.

Two points:

1. A fan blade that "rotates forward" will almost immediately result in a blade tip/case strike. The resulting forces acting on the blade will cause the blade to fail at the fatigue crack.

2. What would cause the fan blade to "rotate forward"? The fan is a compressor section. In other words, in a turbo fan engine the fan blade compresses the air, it does not accelerate the air like a propeller. Further, the huge tension forces resulting from the massive centripetal acceleration of the blade will overwhelm any aero force pushing on the blade. Consider a guitar string. It is under considerable tension. Can you blow on the string to cause it to bend? No. The tension on the fan blade is several orders of magnitude greater than the tension on the guitar string.
Mostly true. Compressor rotating section typically increases flow velocity, stator increases pressure. although depends upon the stage and design, and the degree of reaction gone into blade design.

Very true about tensile stresses, which far exceed bending stresses by a significant factor. This actually stiffens the blade considerably in the varying pressure field it operates. one would be very surprised, even at max chat, if a blade would make it outside the cowl without smashing into the edge, as the cetrepetal forces compared to aero forces are massive. My type, you can actually see the fan bending forward at the tips at Max, at least an inch forwards, due to the forces on the blades. The centripetal element is why blades stretch and the cowl has a frangiable seal which wears away as the blades stretch to maintain efficiency. Google turbine creep, the situation is far worse in the hot section.

[visibility3miles]

Naive question: Although the broken fan blade may have been going at ballistic speeds and bounced off of the cowling before its final trajectory through an aft window,
Wouldn't the 500 knot forward speed of the aircraft have some/ a major influence on its being blown backwards midflight?

After all, if a skydiver leaves a plane, they get blown backwards as they are not as aerodynamically sleek as the plane itself nor under power, especially if the plane is going faster than their rate limiting speed in freefall.

[NWA SLF]

According to the NTSB press conference the blade broke in two places, near the root and further up. They have the section nearest the root, they don't have the outboard section. Doesn't that suggest that the section of blade nearest the root went backwards into the engine? If the speculation about the blade shooting forward and clear of the engine was correct, it seems almost certain they wouldn't have either section.

You got it! NTSB and other sources say the blade is in 3 pieces, the dovetail end is still in the hub, about half of the rest of the blade was recovered in the engine, and the outer part is missing. The inner portion to dovetail end has the interior fatigue crack. They don't say anything special about the fracture at the blade midpoint. Possibilities are the fatigue crack caused the initial failure and the outer portion broke into 2 pieces when it hit the containment ring or the outer fracture occurred due to impact with other blades. It appears certain the broken blade end did not shoot forward due to normal dynamic loading but may have been ejected by impact with other blade. The big unknown is how this caused such massive damage to the inlet. Two broken blades, 2 similar cowling failures. Yet there have been many bird hits with blade damage and without similar cowl failures.

[Intruder]

Nobody knows exactly what the blade hit on its way out, and what else in the cowling was cut off in what direction. It is entirely possible that a piece of something from/in the cowl ricocheted and hit the window. All it had to do was weaken the window enough that the differential pressure could do the rest. Since there was no debris visible inside the cabin, I consider this the more likely scenario.

Also, even a "tight" seat belt is NOT "TIGHT". If you've never strapped into an airplane for planned negative-G acrobatics, you don't know how loose even a normal "tight" seat belt is. Virtually any passenger will have the belt VERY loose in cruise, allowing for significant upward movement if enough force is applied...

[slfool]

Nobody knows exactly what the blade hit on its way out, and what else in the cowling was cut off in what direction.

DOT/FAA/AR-99/11 "Large Engine Uncontained Debris Analysis" which I posted a link to earlier contains both post-incident analysis and modelling information, and takes into account both the mechanical and aerodynamic forces at play when there is a failure. Even a quick scan makes it clear that the dynamics are very complicated, for example there may be secondary fragments caused by debris being ejected out of the front of the engine, then re-ingested and flung out again. Damage is to be expected both ahead and behind of the point of failure, although from looking at the diagrams it appears that the majority of it will be behind the point of failure.

[etudiant]

Should not this accident, coming on the heels of several other surprisingly damaging engine failures, cause a review of our ETOPS requirements?
It certainly appears that large fan engine failures can be more complicated and more damaging than previously anticipated.

[MarkerInbound]

The new EAD is signed as follows:

Original signed by
Karen M. Grant, Acting Manager
Engine and Propeller Standards Branch,
Aircraft Certification Service.

Does this mean the previous "manager" has been sacked for not doing his/her job?

The FAA has an "acting" -

Administrator
Deputy Administrator
Chief of Staff
Associate Administrator Airports
Assistant Administrator Finance and Management
Assistant Administrator Next Gen

And on and on. The previous manager for Engines and Propeller Standards died a couple years ago. Ms Grant has been in that office all this century. They probably don't want to make her position official as she'd go up a notch in pay.

[TXGliderPilot]

Regarding the passenger partially exiting the window: Can anyone provide an analysis of the Bernoullie forces involved? Most of the analyses seem to assume that the only force is due to the pressure differential between the cabin interior and the aircraft exterior. However, a 500 knot airflow past an open window must create substantial additional pressure differential. Might this help explain the difficultly in retracting the passenger from the window?

[IFixPlanes]

Now there are only 20 days (!) left to check the Blades with more than 30.000 FC on the 737 NG:
FAA AD 2018-09-51 (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/6de148fe35ddeddb8625827500759aa4/$FILE/2018-09-51_Emergency.pdf)

[infrequentflyer789]

During conversion and routine refresher training both Engine Severe Damage Separation and Depressurisation exercises are flown. Both events require prompt memory actions. What is unique(?) in this event was that both situations occurred either simultaneously or very close together.

Not unique - both situations occurred in exactly the same order and very close together, with same initial cause, on N766SW in 2016.

Due to the vagaries of the media circus there was comparatively little media interest in that one, probably because nobody died. We don't even know the names of the crew involved (not made public, that I can find) - they got everyone down safely but apparently they weren't heros. We do, however, know from published selfies that things were very different in 2016 in that pax could fit oxygen masks correctly back then :), no really: https://www.thesun.co.uk/wp-content/uploads/2016/08/nintchdbpict000262490017.jpg?w=960

[ManaAdaSystem]

There's something that puzzles me.
All over the Planet Earth it's being mentioned Mrs. Tammie Jo Shults as "the hero pilot, bla, bla,bla".
But listening to the radio exchange (brief and complete ones) between ATCs, TWR & AC, there's one thing very clear: THE PIC DURING ALL THE DESCENT WAS F.O. Mr. Darren Ellisor.
Mrs. Shults was in charge of radio and -surely- checklists while Mr. Ellisor was PIC descending and later aligning for a visual long final.
I've got not clear if Mr. Ellisor was PIC at the moment of the engine failure.

You don’t know the difference between the PIC and the PF?
Only one PIC in the cockpit. Who is PF and PM may change several times during a flight.
I have never had an emergency like this, but in the simulator I will give control to my Effoh when there is a problem. Managing and flying at the same time is a bad combination.
I take back control for the landing. Only myself to blame if something goes wrong at that stage.

FL5 landing is not dictated by any non normal checklist. I say it was a good call. You look out and see damage to the leading edge. You want to slow down as much as possible, but are unsure if you can get control problems when you extend your leading edges. You try FL 5 and LE in mid position. It works.
You land with this configuration. I don’t know the runway length but a -700 is not that hard to stop on a normal length runway even in a flapless configuration.

This emergency involved multiple priority checklists, non normal configuration, compromises, etc.
You can all keep digging for mistakes and look for ways to criticise this crew, but they did a great job.

[bud leon]

With the SW 3472 incident in 2016, plus the SW 438 incident in 2007, and now this, I think the focus of attention needs to be as much on the cowl as the blade. In two (perhaps all three) cases the root of an N1 fan-blade failed (due to fatigue on the 2016 incident) and the blade separated.

But in all three cases the blade appears to have missed the containment ring and struck the cowl instead, causing a complete failure of the cowl, and all the attendant risks with all that material flying off into the slipstream. If you look at the N1 containment ring on the recent incident, it appears to be untouched all the way around. But the cowl took the full force of the departing blade, and disintegrated.

The N1 blade is under considerable aerodynamic forward pressure in flight, and will naturally spring forwards when released. But in static testing for cerification the blade still seems to hit the containment ring. Yet here it appears that the blade moved forward enough to miss the containment ring, and strike the cowl. Perhaps an engineer on this board might suggest why that might be. Why would the forward speed of the aircraft have any effect on the trajectory of the departing blade?

ST

The fan blade following the failed blade is deformed. One possible answer to your question is the blade was propelled forward by the impact of the following blade.

[wiedehopf]

So reading this statement from SWA
https://twitter.com/SouthwestAir/status/987487170947637248

Does this imply that the AD was already performed on the fan blade that failed and was not effective in detecting the problem?

[EDLB]

Unlikely. You can be sure that the FAA/NTSB pulled all relevant engine maintainance logs already.

[aterpster]

So reading this statement from SWA
https://twitter.com/SouthwestAir/status/987487170947637248

Does this imply that the AD was already performed on the fan blade that failed and was not effective in detecting the problem?

The way I read it, they have the capability to comply with the AD without any additional maintenance staff or equipment.

[wiedehopf]

The way I read it, they have the capability to comply with the AD without any additional maintenance staff or equipment.

thank you that would make more sense. still the wording is unfortunate.

[CONSO]

I say it was a good call. You look out and see damage to the leading edge. You want to slow down as much as possible, but are unsure if you can get control problems when you extend your leading edges. You try FL 5 and LE in mid position. It works.

many many years ago, during the first flight of the 767 one leading edge slat jammed and curled back over the leading edge- due to a poorly designed actuation linkage. The other side was as I recall could only be partially extended for the same linkage problem. The resultant landing was very fast so as to maintain control and had some very hot brakes as a result So the first 5 or 6 airplanes had to have major rework in that area before delivery. How do I know this? Was involved in the tooling side of the rework.

[RatherBeFlying]

Large Engine Uncontained Debris Analysis
DOT/FAA/AR-99/11
http://www.tc.faa.gov/its/worldpac/techrpt/AR99-11.pdf

Slfool, Excellent find:ok:

[cavortingcheetah]

https://www.cfmaeroengines.com/press-articles/cfm-statement-incident-wn1380/

[Herod]

ManaAdaSystem. Your post 340. Agree totally

[climber314]

350 Million Flight Hours with minimal problems on the CFM56 Family.
Sounds like a pretty good track record.
Risk is never ZERO.

[Niner Lima Charlie]

Southwest gives US$5000 plus a US$1000 travel voucher to each passenger. This article also has a nice summary of other rapid decompression events in airline history. There have been many others in business jets and military aircraft.

https://www.bloomberg.com/news/articles/2018-04-20/southwest-airlines-gives-5-000-to-passengers-on-fatal-flight

[PineappleFrenzy]

Nobody knows exactly what the blade hit on its way out, and what else in the cowling was cut off in what direction. It is entirely possible that a piece of something from/in the cowl ricocheted and hit the window.

This!

It seems strange to me that so many people here seem focused on generating magic bullet theories about how the departed fan blade struck a cabin window well aft of the event when most of the damage to the cowling was due to engine imbalance.

Is it so hard to believe that the massive forces shaking the cowling apart could to throw debris into the air-stream with sufficient force to dislodge a cabin window?

Given the delay between the initial blade failure and the window failure, I think the evidence available supports the hypothesis that pieces of the cowl, or other secondary debris struck the window as the unbalanced engine wound down.

I've seen enough footage of imbalanced rotating objects destroying things to know you should never underestimate the devastating effects such phenomena can have on their surroundings.

Note that in the first two videos below, the engines are mounted in test stands which are far more rigid than an airplane's engine pylon. In flight, I would expect a lot more movement of the engine during wind-down:

https://www.youtube.com/watch?v=5-8_Gnbp2JA
https://www.youtube.com/watch?v=wcALjMJbAvU

These videos are of helicopters, but illustrate how quickly things can go wrong when rotating parts are no longer balanced:

https://www.youtube.com/watch?v=v5aMT9MBfZI
https://www.youtube.com/watch?v=8BnES4T1RDk

[DaveReidUK]

350 Million Flight Hours with minimal problems on the CFM56 Family.

800 million, in fact, as of a couple of years ago.

Up In The Air: The World’s Hardest-Working Jet Engine Has Logged 91,000 Years in Flight (https://www.ge.com/reports/up-in-the-air-the-worlds-hardest-working-jet-engine-has-logged-91000-years-in-flight/)

[DaveReidUK]

It seems strange to me that so many people here seem focused on generating magic bullet theories about how the departed fan blade struck a cabin window well aft of the event when most of the damage to the cowling was due to engine imbalance.

I don't see many posters maintaining that the departing blade struck the window, particularly in view of the NTSB's early finding that no window fragments were found inside the cabin.

As for the damage to the nose cowl being largely due to out-of-balance forces rather than to the blade scything through it, I think your earlier advice applies:

A fan blade departed and bad things happened. The NTSB will tell us exactly what happened, and why.

[snowfalcon2]

Anybody seen pictures yet of the remains of the failed fan blade?

[RAT 5]

It seems strange to me that so many people here seem focused on generating magic bullet theories about how the departed fan blade struck a cabin window well aft of the event when most of the damage to the cowling was due to engine imbalance.

The NTSB experts speculated it would be 12-15 months for their report to be concluded. it seems some patience is required by the amateurs. :bored:

In 355 replies there is very little comment about the 'piloting input' and about what was done and what you might have done; except for some total rubbish about RT. I'm glad there was this level of expertise up front. Given the severely reduced command time in some carriers worldwide this could have been a very different outcome.

[ph-sbe]

Oh but there is a reason to declare an emergency and even more importantly squawk 7700.

the controller you are speaking to - who does not have authority for the airspace you have descended into - having to add multiple ground line calls to her/his workload.

Agree on the 7700, but do we have any indication that this was not done as part of the checklist or even memorized items?

Workload on the ground: I could not care less about that. The ground has infinite resources compared to the flight deck. The moment that an emergency becomes apparent, whether explicitly declared or not, that controller will already have help from either his supe or colleagues.

Moving workload from the controller to the flight deck, even if it is reduced by a factor 10, is a big no-no imho.

In the end, it boils down to this: the flight crew made it clear that they had a problem and needed to land immediately. From that point on, it is up to the controller to ensure that they get priority handling and as much air space as they need. And if you listen closely, the controller did warn them about traffic below them which was a factor during the initial descent. There was absolutely nothing unprofessional about either the flight crew or the controller.

And on a side note: ICAO standard phraseology exists for one purpose only: to ensure that flight crews and ATC have an unambiguous understanding of each other's intentions and communications. In many cases, that results in longer than strictly necessary speech to accommodate non-native English speakers. Being a non-native English speaker myself, I do appreciate that. At the same time, I cannot critique a native English speaking crew talking to a native English speaking controller diverting from standard ICAO phraseology in an emergency situation where communications and intent are clear on both ends.

In short: there was no need to explicitly yell "Mayday-Mayday-Mayday" or "we are declaring an emergency". It would only consume much needed brain cycles.

[lomapaseo]

PineappleFrenzy

Is it so hard to believe that the massive forces shaking the cowling apart could to throw debris into the air-stream with sufficient force to dislodge a cabin window?

yes it's hard to believe

The blade loss video show large motions at the inlet, but motion alone is not enough. You have to couple it with mass and rate of change.

The even more challenging forces are gust loads in extreme turbulence or aircraft upsets and these don't end up like what you see in the pictures. As long as the inlet remains a box structure designed to aircraft principals it will hold up through all types of loadings.

[lomapaseo]

Large Engine Uncontained Debris Analysis
DOT/FAA/AR-99/11
http://www.tc.faa.gov/its/worldpac/techrpt/AR99-11.pdf


Slfool, Excellent find:ok:

my life just passed in front of me :)

[Concours77]

PineappleFrenzy.

“Given the delay between the initial blade failure and the window failure, I think the evidence available supports the hypothesis that pieces of the cowl, or other secondary debris struck the window as the unbalanced engine wound down...”

Wound down sure. Absent a shaft brake or lock, what does windmilling do in such a circumstance?

[vapilot2004]

Just about all aero structures have critical vibration frequency and amplitude limits. Engine cowling is no different.

It is primarily designed for noise suppression, with strength considerations for ramp rash (nose cowl) and anti-flutter properties (clamshell & nose cowling). Modern engine cowlings are not considered primary protective structures from high energy engine parts. That's the purpose of the engine and fan cases.

While obvious, it is useful to recall that blade out test rigs are designed primarily to evaluate the disk, fan, and fan case strength and performance. The inlet bell is a multi-purpose structure that has no bearing on the blade test data, by design, outside of the purpose of containing the high energy fragments.

[tdracer]

Wound down sure. Absent a shaft brake or lock, what does windmilling do in such a circumstance?
The windmilling vibration loads are still tremendous - the FAA has made Boeing show that the rest of the aircraft can readily handle the blade out vibrations for an extended ETOPS diversion - it wasn't trivial.
One story was that after a blade out event on a 747, the aircraft vibrations were so severe the crew had difficulty reading the flight deck gauges (one variation of the story - perhaps antidotal - was that there was a Boeing exec on the flight - after the flight he promptly asked engineering to go make sure the aircraft could handle that level of vibration..)

[CONSO]

The windmilling vibration loads are still tremendous - the FAA has made Boeing show that the rest of the aircraft can readily handle the blade out vibrations for an extended ETOPS diversion - it wasn't trivial.The load on engine mounts and wing structure can be significant. For an extreme case- check out whirl mode on the Electra problem/flutter due to 'engine mount ' failures. Sufficient to tear off a wing in a few seconds. Granted the current problem was different in many respects- but the point of high frequency vibrations on structure is real . For low frequency vibrations caused by simple aero loading and what they can do without damping - google galloping gertie.:8

[PineappleFrenzy]

PineappleFrenzy.

Wound down sure. Absent a shaft brake or lock, what does windmilling do in such a circumstance?

Windmilling simply adds more opportunity for parts to shake loose. It also stresses the airframe.

Given the lack of vibration depicted in video of the SW1380 incident, I'd say the engine wasn't windmilling at all. The first two videos below show what it's like inside an airplane with a windmilling but unbalanced engine.

As seen in previous catastrophic engine failure events, often the initial shaking caused by an unbalanced high speed rotating mass is so strong that the engine simply sheds its exterior components (see the third video), if it isn't ripped from the pylon altogether. Even when blades remain within the containment ring, and even if friction prevents the engine from windmilling, it certainly seems possible for a piece of the cowling to catch the airflow at just the right angle to lead it directly into the side of the plane and damage a window as the engine winds down.

AirAsia X D7237:
https://www.youtube.com/watch?v=_J5QsbA_QzQ

United 1175:
https://www.youtube.com/watch?v=f2TEJbm-HE4

Exterior shot of United 1175:
https://www.youtube.com/watch?v=mGm-obltrtQ

[lomapaseo]

tdracer

the FAA has made Boeing show that the rest of the aircraft can readily handle the blade out vibrations for an extended ETOPS diversion - it wasn't trivial.
One story was that after a blade out event on a 747, the aircraft vibrations were so severe the crew had difficulty reading the flight deck gauges (one variation of the story - perhaps antidotal - was that there was a Boeing exec on the flight - after the flight he promptly asked engineering to go make sure the aircraft could handle that level of vibration..)

The FAA also included all other plane manufacturers as well in the assessment. Tis true some interesting windmill events did occur but they were all associated with the loss of the engine front shaft support and did not otherwise degrade other critical structures or the ability to fly the aircraft.. Nevertheless the loads developed were well within the design loads for manuever and gust loading in the aircraft certification base.

The worst part of it was that the passengers were not happy as the aircraft went through a critical windmill speed range while landing.

As for reading the flight deck instrumentation we confirmed that the crews could fly the aircraft with no problem. We got one famous chap to sit on a laboratory shake table and cranked it up to the expected frequency and amplitude for a time and he had no complaints and slept for days afterwards.

[OddballM4]

The FAA has an "acting" -

Administrator
Deputy Administrator
Chief of Staff
Associate Administrator Airports
Assistant Administrator Finance and Management
Assistant Administrator Next Gen

And on and on. The previous manager for Engines and Propeller Standards died a couple years ago. Ms Grant has been in that office all this century. They probably don't want to make her position official as she'd go up a notch in pay.

Not really germane to the rampant speculation on this event; but...

Gov employee here (not FAA or NTSB, but another federal safety regulator). While 17+ years seems kind of long in my experience (has she really been an actor in that role for that length of time, or are you extrapolating her time in service with the FAA to that one position - people do move around a lot in Fed agencies), acting managers are a fact of life in government service. It takes time to post, interview, hire (most often from within) for a management position in a Fed agency. Also, there are generally time limits on how long one can act in a higher-graded position without receiving the higher-grade pay.

Most of us - even the managers - are competent professionals just trying to do our part to serve the public. This even applies to the political appointees (although I'll grant it 's become more of an exception in the last year or so :ouch: ). I thought Chairman Sumwalt did a fine job in the media briefing posted earlier.

Back to lurking. Thanks to the many professionals who make this site such an engaging read for this wanna-be aviator.

[jugofpropwash]

PineappleFrenzy.

“Given the delay between the initial blade failure and the window failure, I think the evidence available supports the hypothesis that pieces of the cowl, or other secondary debris struck the window as the unbalanced engine wound down...”

Wound down sure. Absent a shaft brake or lock, what does windmilling do in such a circumstance?

I don't think we really know how much of a delay there was between the blade failure and the window failure. Passengers have stated that there was some delay between the initial explosion and the masks dropping, and another delay between the masks dropping and the passenger being sucked out, but how reliable are those accounts, and how much of a delay? Even if that is an accurate chain of events, and a short span elapsed between each, I don't think that eliminates the possibility of something (partial fan blade or other material) from the initial event hitting the window. It would seem a glancing blow could have caused a crack or small hole, which as it spread caused cabin pressure to go down/masks to drop, before failing completely. Am I wrong? Unless they find the pieces (highly unlikely), I doubt if they will ever determine exactly what caused the damage.

[tdracer]

Unless they find the pieces (highly unlikely), I doubt if they will ever determine exactly what caused the damage.
They found paint transfer marks on the fuselage, so it's pretty much established that parts of the nacelle impacted the fuselage.
It should be fairly straightforward to determine if the damage around the paint marks correlates with the window failing.

[Highway1]

I don't see many posters maintaining that the departing blade struck the window, particularly in view of the NTSB's early finding that no window fragments were found inside the cabin.


Well I have responded to several - it does seem to be a common assumption. Not sure what the relevance of window fragments would be as they wouldn't confirm blade impact or impact by parts of the nose or fan cowl.

FWIW my money is still on the fan cowl..

[DaveReidUK]

Given the lack of vibration depicted in video of the SW1380 incident, I'd say the engine wasn't windmilling at all. The first two videos below show what it's like inside an airplane with a windmilling but unbalanced engine.

AirAsia X D7237:
https://www.youtube.com/watch?v=_J5QsbA_QzQ

United 1175:
https://www.youtube.com/watch?v=f2TEJbm-HE4

I'm not sure you can make a direct comparison between the out-of-balance forces produced by a windmilling Trent or PW4xxx compared to a CFM56.

[VinRouge]

PineappleFrenzy



yes it's hard to believe

The blade loss video show large motions at the inlet, but motion alone is not enough. You have to couple it with mass and rate of change.

The even more challenging forces are gust loads in extreme turbulence or aircraft upsets and these don't end up like what you see in the pictures. As long as the inlet remains a box structure designed to aircraft principals it will hold up through all types of loadings.

You get some interesting aeroelastic effects at higher IAS. So it's not just about the structure witholding the fan when it fails. Those blade off tests don't show incoming air at around 250-270kts IAS. Only takes a part to become partially detached into the airflow and it will start to tear apart. Even if it witholding the fan, the weakened structure may struggle to stay attached. Be more concerned what could happen if the cowl, accelerated in the air flow, were to impact the vertical or horizontal stab.

[rob_ginger]

In this news article http://www.bbc.com/news/world-us-canada-43804253 (http://http://www.bbc.com/news/world-us-canada-43804253)
I saw this quote:

For a few seconds, the aircraft rolled to an angle of 41 degrees before levelling out and starting an emergency descent, federal investigators said on Wednesday.Does that sound right? Haven't seen it mentioned in this thread or anywhere else. If true it seems like quite a significant roll. What would cause that?

[Chesty Morgan]

Yaw.
......

[core_dump]

Yaw.

NTSB board member Robert Sumwalt said during one of the briefings that the bank angle reached 41.3 degrees (or was it 41.5?). He then proceeded to say that your first reaction would be to grab the yoke and correct it. Since he was an airline pilot for 24 years, I doubt he would have confused bank angle with yaw. Certainly one of the staffers may have given him misinformation, but it doesn't sound like it. (Edit: I misunderstood Chesty's terse answer. My apologies.)

Link to relevant portion of briefing (https://www.youtube.com/watch?v=EL5eMVGz5gk&feature=youtu.be&t=118)
The aircraft began a rapid uncommanded left roll of about 41 degrees of bank angle. So usually when you're flying on an airliner you rarely get over about 20-25 degrees of bank. This went over to 41 degrees. The pilots leveled the wings.Then during the Q&A one of the reporters asked him about the roll and he elaborated: Link

[jaytee54]

[QUOTE= Since he was an airline pilot for 24 years, I doubt he would have confused bank angle with yaw. But certainly one of the staffers may have given him misinformation.
I found that tidbit during the briefing very interesting as well.[/QUOTE]

following the question
"If true it seems like quite a significant roll. What would cause that? "

and answer "yaw"

What Chesty Morgan (of few words) probably meant was that engine failure causes asymmetric loss of thrust which causes yaw towards the failed engine, and the yaw coupled with wing sweepback causes significant ROLL
QED

[DaveReidUK]

What Chesty Morgan (of few words) probably meant was that engine failure causes asymmetric loss of thrust which causes yaw towards the failed engine, and the yaw coupled with wing sweepback causes significant ROLL

Those considerations apply, of course, to any engine failure in a twin.

How many of those result in rolling almost halfway to the vertical ?

While Chesty's succinct responses are always to be admired, in this case a few more words of explanation might have helped ...

[LowAndSlowTX]

Those considerations apply, of course, to any engine failure in a twin.

How many of those result in rolling almost halfway to the vertical ?

While Chesty's succinct responses are always to be admired, in this case a few more words of explanation might have helped ...

Normally when you have gotten up to the point where you are talking to center (at the higher altitudes), things are fairly relaxed (George, the autopilot is doing its thing) and direct hands-on-the-yoke is several minutes in the past. A bang and shudder takes a few seconds to determine something serious has gone wrong, and may have even gotten both sets of eyes on the engine instruments, attempting to decipher exactly what had happened, with feet not on the rudder peddles.

With those big fat dumpsters out on the wing, the drag, assuming the fan stopped fairly quickly, could be a tremendous yaw/roll.

On takeoff, your concern is complete control if such an event happens at low speed, as the ground is right there waiting, so hands and feet at literally on or near the controls on both sides. At altitude, the crew thought process is much more relaxed.

[Chesty Morgan]

I suspect not many happen near top of climb, probably feet up, with a coffee.

15 words! I’m done in:p

[aterpster]

This even applies to the political appointees (although I'll grant it 's become more of an exception in the last year or so :ouch: ). I thought Chairman Sumwalt did a fine job in the media briefing posted earlier.


He is probably the best chairman the NTSB has had. He was elevated to chairman by the present administration. Bob is a former airline pilot and ALPA safety rep. He also has an abundance of common sense and tact.

[gums]

TNX for the education Chesty and others.

I was surprised at the amount of roll, but I guess with the motors at near-full thrust that the lack of thrust on one as well as increased drag from the damage was enuf. Also was prolly a fairly low "q" so aero authority of vertical stab likely low.

Yaw can cause significant roll even in straight wing planes depending on engine alignment with the aerodynamic longitudianl axis and not necessariy the physical. So you can get decent roll even on symmetrical thrust twins, and I flew one that required immediate full rudder and pulling the good engine back from mil thrust. Lost two folks on single engine go arounds because of that, especially if they were pullng back on the stick to get the nose up.

On the bent wing planes, the roll due to yaw can be extreme. Flying some fighters, we used nothing but rudder for roll when at high AoA, with stick locked between your knees. But 41+ degrees of roll within seconds at that stage of flight would sure get my attention, heh heh.

Gums sends...

[RAT 5]

Dangerous, but I'm going to make some assumptions. Engine failure, yaw, roll, autopilot tries to keep wings level with ailerons and control column goes to full scale PDQ. No doubt there was quite a bang. Autopilot lets go and a/c rolls. That would happen in only a few seconds. The startle factor must have been severe.
I wonder who was PF, but if I was captain I think I would have my hands and feet doing their thing. That in itself would be interesting if F/O (as PF) was also doing his thing. Knowing who had control would be essential, quickly.
One engine out FL325 means immediate descent, perhaps at idle to help control the yaw/roll. That needs ATC coordination/communication. A drift down in the scenario was highly unlikely.
Somewhere during the analysis of the engine bang they were then presented with the cabin ALT warning, then emergency descent.
This is worse than a bad hair day, and indeed at Gums says, idle thrust on the live makes life easier. They did have lots of height.
I'll be curious when/if they re-engaged the autopilot to reduce work load. The idle thrust on live + drag on sev damage engine would still give some yaw/roll problems, but rudder trim should have been enough to help the autopilot.
This really would have been a scenario of ANC & priorities.

I was curious, in the NTSB briefing, how he mentioned, and repeated the landing speeds for F30/40 landing; explaining their F5 landing was 30kts faster than normal. Difference between F5 & F15 is 10kts.

Good to hear the CVR/FDR and crew debriefing is underway expeditiously.

[DaveReidUK]

Dangerous, but I'm going to make some assumptions. Engine failure, yaw, roll, autopilot tries to keep wings level with ailerons and control column goes to full scale PDQ. No doubt there was quite a bang. Autopilot lets go and a/c rolls. That would happen in only a few seconds. The startle factor must have been severe.

I suspect also, as alluded to by Gums, that the effect on L/D of the nose cowl being shredded and subsequently departing was a significant factor contributing to the degree of uncommanded roll, compared to an everyday engine failure.

[aterpster]

Article about ADs and SBs in MRO:

EASA, FAA Issue Emergency ADs For CFM56-7B Inspections | MRO Network (http://www.mro-network.com/engines-engine-systems/easa-faa-issue-emergency-ads-cfm56-7b-inspections)

[Concours77]

https://dynaimage.cdn.cnn.com/cnn/livestory/w_900/57a4834c-ff2f-4e6f-8387-66ef66c7bbdf.jpg

From the peeling forward of the lapped inner skin of the inlet and the clean departure of the honeycomb in circumferential and crisp fashion, I would think the structures were “blown out” forward. That would make a blade separation a result of, and not the cause of the severe damage....

[DaveReidUK]

From the peeling forward of the lapped inner skin of the inlet and the clean departure of the honeycomb in circumferential and crisp fashion, I would think the structures were “blown out” forward. That would make a blade separation a result of, and not the cause of the severe damage....

How does the evidence of fatigue at the root of the departed blade fit in with that scenario ?

[bsieker]

https://dynaimage.cdn.cnn.com/cnn/livestory/w_900/57a4834c-ff2f-4e6f-8387-66ef66c7bbdf.jpg

From the peeling forward of the lapped inner skin of the inlet and the clean departure of the honeycomb in circumferential and crisp fashion, I would think the structures were “blown out” forward. That would make a blade separation a result of, and not the cause of the severe damage....

How does the evidence of fatigue at the root of the departed blade fit in with that scenario ?

Also, Concours77, what do you think could "blow out" the front of the engine in such a way that it only damages part of the cowling, which is a relatively weak material, but then is also powerful enough to snap off a fan blade, which is very strong indeed unless there already is a fatigue crack.

The only think I know which "blows out" of the front of the engine would be a surge, but these rarely damage the engine, although they can be spectacular. I can't imagine that one would ever blow out a fan blade.

Bernd

[MarkerInbound]

Not really germane to the rampant speculation on this event; but...

Gov employee here (not FAA or NTSB, but another federal safety regulator). While 17+ years seems kind of long in my experience (has she really been an actor in that role for that length of time, or are you extrapolating her time in service with the FAA to that one position - people do move around a lot in Fed agencies), acting managers are a fact of life in government service. It takes time to post, interview, hire (most often from within) for a management position in a Fed agency. Also, there are generally time limits on how long one can act in a higher-graded position without receiving the higher-grade pay.

Most of us - even the managers - are competent professionals just trying to do our part to serve the public. This even applies to the political appointees (although I'll grant it 's become more of an exception in the last year or so :ouch: ). I thought Chairman Sumwalt did a fine job in the media briefing posted earlier.

Back to lurking. Thanks to the many professionals who make this site such an engaging read for this wanna-be aviator.

Just to clarify, Ms Grant has been in the Engine and Propeller Standards branch of the FAA for 15 plus years. She appears to have assumed the duties of acting Director after the death of the previous manager in 2015.

Climber314 seemed to imply that her "acting" status may have been due to fallout from the SW accident and I was just pointing out that most of the FAA senior management is in acting positions.

[Concours77]

How does the evidence of fatigue at the root of the departed blade fit in with that scenario ?

It makes the surge theory case; a surge causes a loss of, and an instantaneous reaction to the peak thrust at top of climb....

IF the blade is compromised by patent fatigue, it suggests the rapid and emphatic change in gas path could cause sufficient failure to further crack the flaw, and exacerbate the separation.

[Concours77]

Also, Concours77, what do you think could "blow out" the front of the engine in such a way that it only damages part of the cowling, which is a relatively weak material, but then is also powerful enough to snap off a fan blade, which is very strong indeed unless there already is a fatigue crack.

The only think I know which "blows out" of the front of the engine would be a surge, but these rarely damage the engine, although they can be spectacular. I can't imagine that one would ever blow out a fan blade.

Bernd

It wouldn’t have to be powerful enough to blow out an (undamaged) fan blade, only sufficiently robust to snap an already cracked one. An important piece of evidence is the character of the “bang”. Never present at an actual blade separation, but I have experienced a very impressive surge in a DC-10 (Mexicana, forty years ago). Number two. A LOT of flame, and a very loud “boom”.

[tdracer]

Concours, losing a fan blade will invariable cause a surge (go look at the videos of fan blade out testing a few pages back).
Cause and effect is 99.99% that the surge was a result of the blade release, not the other way around...
Also, healthy CFM56 engines very seldom surge. Oh, and the number 2 engine on the DC-10 was notorious for surging during climb - flow distortion from the fuselage at higher angles of attack.

[Concours77]

Concours, losing a fan blade will invariable cause a surge (go look at the videos of fan blade out testing a few pages back).
Cause and effect is 99.99% that the surge was a result of the blade release, not the other way around...
Also, healthy CFM56 engines very seldom surge. Oh, and the number 2 engine on the DC-10 was notorious for surging during climb - flow distortion from the fuselage at higher angles of attack.

:ok::ok::ok:

[DaveReidUK]

It makes the surge theory case; a surge causes a loss of, and an instantaneous reaction to the peak thrust at top of climb....

IF the blade is compromised by patent fatigue, it suggests the rapid and emphatic change in gas path could cause sufficient failure to further crack the flaw, and exacerbate the separation.

Interesting theory, could be true, but Occam's Razor points to a more obvious sequence of events starting with failure of a weakened blade.

[MightyOneFiveTwo]

Furthering Councours77's musing:
Evidence of pre-existing fatigue damage does not *necessarily* mean that the fatigue failure was primary. It's entirely plausible that some external factor caused loading to the blade in excess of what the remaining material could support, at which time it would fail at the fatigue site and expose the defect.

You'd want to do some analysis -- normally you can tell what part of a fracture face was progressive and what part was sudden, assuming it's not too bashed up by subsequent events. In the state the blade existed in just before the failure, was the remaining strength enough to withstand the normal operating forces (within some reasonable tolerance)? This is a fairly simple calculation.

If it's near the margin, then the most likely scenario is indeed that the fatigue fault grew until time ran out and the blade snapped off under normal (-ish) loads. If it should have still held under normal conditions, even in its degraded state, then you'd need to look for additional precipitating conditions.

What those conditions might be goes into pure uninformed speculation (on my part at least). A whopping surge prematurely disassembles part of the inlet, say, and re-ingested debris whacks the weakest blade?

I understand the general thinking is that a surge should not fracture a blade -- but what if it were approaching the point where it was going to come off soon? Here's a question: is a surge symmetrical (or maybe I should say circumferentially uniform)? During a surge event, does a given blade rotate through drastically different aerodynamic conditions as it spins around? How many revs are made during the typical duration of the upset flow? I think I've seen in the FBO test videos I've watched that sometimes the visible exit of combustion gases through the fan is asymmetrical, at least for part of the event. That would create a cyclic load that is (probably) much different than the design loads.

For that matter, under normal operating conditions, is the pressure/velocity uniform circumferentially around the fan? I can imagine it might not be, especially under large AOA (thinking about a simple prop clawing through the air in climb attitude).

I agree that the simplest and cleanest scenario is that the blade failure was primary, but there are things about that which nag at me. Not the least of which being that this event doesn't seem to conform to what is seen in static blade-off testing. Relying on a testing regime that *may* not accurately capture real-world failure scenarios is not a comfortable place to be.

For the record, I'm neither a pro pilot nor an aviation engineer, but I am a mechanical engineer who has too many years of this sort of failure analysis under my belt. And because of that I am still in awe of the detail and quality of the investigations the NTSB does!

Looking forward to what the professionals say when it's all wrapped up. Back to lurking and learning.

[lomapaseo]

I see a lot of bubble and boil going on here, so I'll drop another onion into the soup.
Blades that fail in fatigue do so under the loads of combined stress between tensile-bending and cyclic high frequency fatigue (Goodman's diagram).

As such any pertubation in the rotating arc of the blade, e.g. probes in the case add just a tiny bit of stress which while not being causal of the fracture does statistically pick the clock location where it does fracture. Thus for a given fleet problem, statistically most blade fractures will occur at the same clock location

[KenV]

Thus for a given fleet problem, statistically most blade fractures will occur at the same clock locationI must be missing something. Every fan blade is at every clock location when the engine is running. Help me out here, what am I missing?

[lomapaseo]

I must be missing something. Every fan blade is at every clock location when the engine is running. Help me out here, what am I missing?

clock position refers to the stationary bits of the engine relative to the top of the engine looking from the rear.

[KenV]

clock position refers to the stationary bits of the engine relative to the top of the engine looking from the rear.I understand that part. What I don't understand is blades fractures occurring "at the same clock position." Every blade is at every clock position when the engine is running. You can't say "the blade at 2 o-clock tends to fail more often than the blades at the other clock positions". So what am I missing?

[Rwy in Sight]

I understand that part. What I don't understand is blades fractures occurring "at the same clock position." Every blade is at every clock position when the engine is running. You can't say "the blade at 2 o-clock tends to fail more often than the blades at the other clock positions". So what am I missing?

Allow to interfere: the numbering is done while the blades don't turn. So the blades have a number as lomapaseo states.

[tdracer]

Ken, what loma is saying is that the failure would happen at about the same engine clock position - not the fan clock position (which as you noted is constantly changing as the fan rotates).
There a inlet probes in front of the fan for total temp (and on EPR engines, total pressure) - these create turbulence/vortices. The big concern for these has been the fan hitting those vortices makes a lot of noise - hence on new installations those probes have been pushed further forward in the inlet to give the airflow a chance to clean up before it hits the fan. What lomapaseo is pointing out is that those probe vortices also cause a once/rev stress on the individual fan blades as they pass - so if there is a cracked fan blade, it is most likely to fail as it passes through the probe wake.

I saw the report on a real severe case of this once/rev stress. A brand new GE90 (I think, it's been ~20 years) came apart during acceptance testing. Turns out part of one of the fuel nozzles hadn't been installed properly and came loose - it moved through the burner and blocked one of the stage one turbine nozzles. So first stage turbine blades saw a massive once/rev stress as they were totally unloaded then reloaded as the passed the blocked nozzle. It took something line 10 minutes at power before the first turbine blade failed :eek:

[CONSO]

I understand that part. What I don't understand is blades fractures occurring "at the same clock position." Every blade is at every clock position when the engine is running. You can't say "the blade at 2 o-clock tends to fail more often than the blades at the other clock positions". So what am I missing?

Lets try again-IMHO a particular spot on the fixed ( non rotating ) part of the engine casing/inlet is defined by ' clock position " The comment was made about an instrumentation device (probably a very small protrubence into the surrounding casing such as a magnetic/proximity/ device to measure rpm/temp/pressure ( approx 5000 rpm I believe ) This then could cause a minor disturbence in the airflow or a minor change in tangential/radial stress when each blade passes )

Over a period of time, given a marginally fatigued blade, this change in stress while quite small **COULD** **MAY** be sufficient to cause that blade to depart within a few milliseconds.
The point was that **IF** that is the case, then the first 'impact' point of the broken blade **COULD** be a function on fan speed and direction. so **IF** the fan speed was the same in a few cases, then the first impact point would **PROBABLY** be in the same relative clock position depending on fan direction eg 9 O'clock or 3 O'clock and x o'clock from the protrubence.

Keep in mind- the comment was re statistics and/or probability of such a comparison - NOT a fixed- proven theory.

Just my .000002 based on my injun-ear background

And after I posted this- I found tdracer comment made a few minutes before I hit save of my tome

[CONSO]

https://www.wsj.com/articles/at-southwest-airlines-the-minutes-after-disaster-struck-1524586032

At Southwest Airlines, the Minutes After Disaster Struck

How top management, using updates from the cockpit and passengers’ phones, put the emergency-response plan into action in Philadelphia and Dallas




By Scott McCartney

April 24, 2018 12:07 p.m. ET 59 COMMENTS (https://www.wsj.com/articles/at-southwest-airlines-the-minutes-after-disaster-struck-1524586032#comments_sector)

All Southwest Airlines (http://quotes.wsj.com/LUV) senior executives were at a Dallas hotel for a day-long meeting on leadership development last week when suddenly phones blared in unison around the room: Flight 1380 was in serious trouble.
The team had a quick conference call with the airline’s operation center, then raced to headquarters nearby. From there they put an emergency-response plan into action.
The plan had gotten a lot of use in the past year: three hurricanes (https://www.wsj.com/articles/hurricane-harvey-inundates-houston-with-widespread-flooding-1503841506?mod=article_inline), plus mass shootings in Las Vegas (https://www.wsj.com/articles/las-vegas-shooting-leaves-several-people-injured-1506927071?mod=article_inline) and Sutherland Springs (https://www.wsj.com/articles/two-dozen-funerals-in-one-texas-town-1510426112?mod=article_inline), Texas, near San Antonio. All required extensive coordination and interaction with customers. But nothing prepared executives for the kick in the gut they got when passenger Jennifer Riordan died.



goes on

[Carbon Bootprint]

https://www.wsj.com/video/series/financial-inclusion-in-america/propel-an-app-that-makes-checking-food-stamp-balances-easier/C2590842-E0F4-4E15-8036-C23B218D64D8

video and some audio of details and near end of video re loss of a blade
I find several videos there, but none that seem to deal with SW1380. Am I missing something? :confused:

[CONSO]

I find several videos there, but none that seem to deal with SW1380. Am I missing something? :confused:

Hmmm try again

https://www.wsj.com/video/southwest-flight-1380-what-happened-onboard/366C7463-2DD5-4AF8-ABCD-ADF6510D3401.html?mod=searchresults&page=1&pos=1 (https://www.wsj.com/video/southwest-flight-1380-what-happened-onboard/366C7463-2DD5-4AF8-ABCD-ADF6510D3401.html?mod=searchresults&amp;page=1&amp;pos=1)

cant figure out how to edit this new fubarproved system

Sorry

And I now am able to delete that previous mess - message ( I think )

[Carbon Bootprint]

That works, Conso. Thanks.

[airsound]

Thanks for that excellent Wall Street Journal piece, Conso. It brings home to me, again, what a wonderfully calming presence Capt Shults has. Under great pressure, she manages to speak in a conversational way in plain English. No, it's not on fire, but part of it's missing. They said there's a hole, and ....... someone went out.
And she, and the FO of course, got it back without further injury. Excellent.

airsound

[CONSO]

Here is another good article from WSJ

https://www.wsj.com/articles/southwest-1380-pilots-steered-a-well-timed-descent-1524834000

Southwest 1380 Pilots Steered a Well-Timed Descent

Abrupt dive was needed to get to a breathable altitude; ‘you can’t do it slower’



ByJo Craven McGinty

April 27, 2018 9:00 a.m. E (https://www.wsj.com/articles/southwest-1380-pilots-steered-a-well-timed-descent-1524834000#comments_sector)
When the left engine of Southwest Flight 1380 broke apart last week, shattering a window of the aircraft and causing the Boeing 737 to lose cabin pressure, the pilots pushed the nose of the plane down and zoomed from 32,500 feet to 10,000 feet (https://flightaware.com/live/flight/SWA1380/history/20180417/1430Z/KLGA/KPHL?mod=article_inline)in about eight minutes.The abrupt dive (https://www.wsj.com/articles/southwest-jet-makes-emergency-landing-in-philadelphia-1523985825?mod=article_inline) led some passengers to describe the change in altitude as a free fall. But the pilots appear to have executed a perfect emergency descent.

[WingNut60]

Did anyone see any confirmed reports of ear problems in any of the passengers?
I'd have expected a few ruptured eardrums with the rate of decompression when the window went.
Possible that some may even have ended up bent.

There was a report of a passenger standing with his back against the empty window port.

It would be interesting to see what happened with cabin altitude at various stages of the descent.
Obviously a sudden drop to drop the masks. But did the fellows butt in the window make any difference? To cabin altitude, that is. Not denigrating his efforts in any way.)

[Bleve]

I'd have expected a few ruptured eardrums with the rate of decompression when the window went.

I wouldn't. With respect to cabin altitude/decompression, the loss of one window is not dramatic. It usually results in the cabin altitude climbing at about 2000-3000 fpm (about the same as the initial climb after take-off). In this event, it wasn't even a full window opening - it was (tragically) partially blocked. So the cabin climb rate would have been even less.

Possible that some may even have ended up bent.

Probably not. Decompression sickness (the bends) becomes an issue above 25,000 feet. The aircraft was about 33,000 feet when they commenced descent. An emergency descent typically achieves about 6,000 fpm rate of descent. Assume a conservative case of the cabin at 14,000 feet and climbing at 2,000 fpm when the descent was initiated. Solving that basic math problem has the aircraft and the cabin altitudes equalizing after 2.375 minutes at 18,750 feet. It's unlikely anyone would get 'bent' at that altitude.

Obviously a sudden drop to drop the masks.

The masks automatically drop when the cabin altitude reaches a predetermined level (usually between 10,000-14,000 feet). The rate at which the cabin altitude is increasing (or the 'suddeness' of the decompression) is irrelevant.

But did the fellows butt in the window make any difference? To cabin altitude, that is.

I'm curious about that as well. I suspect that they were only able to pull the lady in after the cabin and outside air pressures were approximately equal. After that the cabin would have been fully depressurised and any air loss from the cabin would have been due to a venturi effect. A butt in the window might slow/stop that. But was it enough to create an effective seal? Did the cabin start to repressurise? Was the gentleman stuck there until the cabin was depressurised after landing? Did he suffer any injuries - eg a Petechial Rash or worse?

[RAT 5]

I wonder what altitude the cabin finally reached. It is the descent, asa much as the climb, where ear problems can occur. A few decades ago there was an Air Europe B757, out of Bangor I believe. They decompressed at crz level. During the emergency descent there were numerous complaints amongst pax & CA's of ear damage/problems. I don't know what the cabin climbed to. If the cabin climbs to crz level, or above 25.000', and then descends at 6000fpm there is a strong chance of ear drum problems.

[jugofpropwash]

I'm curious about that as well. I suspect that they were only able to pull the lady in after the cabin and outside air pressures were approximately equal. After that the cabin would have been fully depressurised and any air loss from the cabin would have been due to a venturi effect. A butt in the window might slow/stop that. But was it enough to create an effective seal? Did the cabin start to repressurise? Was the gentleman stuck there until the cabin was depressurised after landing? Did he suffer any injuries - eg a Petechial Rash or worse?

Assuming the story about the passenger blocking the window is accurate, it might have been done to keep anyone else from falling out, rather than actually trying to block the air flow. For that matter, it could simple have been done to reassure the other passengers, who were probably freaking about "Gaping hole in the plane! Ack!"

[CONSO]

I wonder what altitude the cabin finally reached. It is the descent, asa much as the climb, where ear problems can occur. A few decades ago there was an Air Europe B757, out of Bangor I believe. They decompressed at crz level. During the emergency descent there were numerous complaints amongst pax & CA's of ear damage/problems. I don't know what the cabin climbed to. If the cabin climbs to crz level, or above 25.000', and then descends at 6000fpm there is a strong chance of ear drum problems.

I suspect when the NTSB-FAA report comes out, there will be a data tabulation/curve showing the change in cabin altitude versus time- My GUESS is that it may have reached 16,000 to 18,000 feet,sinc it was likely that the pressurization system reduced the rate of depressurization. Somewhere there should be design or test data- regulations which would accommodate the loss of one window at cruise altitude.

[lomapaseo]

Somewhere there should be design or test data- regulations which would accommodate the loss of one window at cruise altitude.

One of the impediments against the early SST proposals was the cruise altitude vs decompression rate vs the size of the holes made by a bursting turbine disk.

[CONSO]

One of the impediments against the early SST proposals was the cruise altitude vs decompression rate vs the size of the holes made by a bursting turbine disk.

perhaps this may help ?

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25-20.pdf

[procede]

it was likely that the pressurization system reduced the rate of depressurization.
With one engine shut doen and the other at idle, I think the pressurization system would not be very effective.

[DaveReidUK]

My GUESS is that it may have reached 16,000 to 18,000 feet, since it was likely that the pressurization system reduced the rate of depressurization.

That sounds possible. It's not necessarily the case that a cabin with a broken window can't hold any pressure - it's akin to having a second one of these, albeit one that's stuck in the open position:

http://www.b737.org.uk/images/main_outflow_valve_ng_new.jpg

[thcrozier]

Depressurization and Ears:

Because of the design of the eustachean tubes, decreasing outside pressure rarely causes problems in a healthy ear. Increasing outside pressure, as in a rapid descent in air, and even more so in water, can cause what divers call “ear squeeze”, which can be very painful and rupture an eardrum if not managed properly.

That’s why you hear far more babies crying during descent than during ascent.

[Airbubba]

President Trump will meet with the crew of Southwest 1380 :ok: :

Donald Trump to meet with crew of Southwest Airlines Flight 1380

FILED UNDER SOUTHWEST AIRLINES (https://www.dallasnews.com/business/southwest-airlines) AT19 HRS AGO
Written by

https://dallasnews.imgix.net/1506471234-CLAIRE_CARDONA_PORTRAIT_2_59016813.JPG?w=40&h=40&q=30&auto=format&fit=facearea&crop=faces&facepad=1.7Claire Z. Cardona, Breaking News Producer (https://www.dallasnews.com/author/claire-z-cardona)Connect with Claire Z. Cardona

President Donald Trump will meet Tuesday with the crew of the Southwest Airlines flight that made an emergency landing this month after a deadly mid-flight engine failure.

They will meet at the White House, but no further details were released about the planned interaction between the president and the Flight 1380 crew.



https://dallasnews.imgix.net/1525045594-PLANE_EXPLOSION_PILOT_62347982.JPG?q=30&w=200&fit=clip&auto=format&frame=1In a photo provided by the U.S. Navy, Lt. Tammie Jo Shults with her F/A-18A jet in 1992. Shults, one of the Navy's first female fighter pilots, was in command of Southwest Airlines Flight 1380 when its engine exploded on April 17, 2018; for the next 40 minutes, she maneuvered the plane safely to an emergency landing in Philadelphia.(THOMAS P. MILNE/NYT)Passenger Jennifer Riordan, 43, was partially sucked out of a window and killed on the April 17 flight when a fan blade broke and caused the engine to fail.

The Dallas-bound plane was safely piloted to an emergency stop in Philadelphia by Captain Tammie Jo Shults, who has been commended for her composure during the crisis and compassion after the landing.

Once on the ground, Shults, a Texan and former Navy fighter pilot, walked up and down the aisle hugging passengers.

Also on board were first officer Darren Ellisor and three other crew members whose names have not been released. The flight was carrying 144 passengers from New York's La Guardia Airport.

While the cockpit crew worked to land the plane, witnesses said the flight attendants tried to help save the injured woman, assisted passengers with oxygen masks and explained where the plane was headed.

In a written statement, the crew said they "were simply doing our jobs."

https://www.dallasnews.com/business/southwest-airlines/2018/04/29/donald-trump-meet-crew-southwest-airlines-flight-1380

[gums]

Gota tellya, Bubba, but 26 years ago I would have been "interested" in Miss Tammie, with a buncha other folks, pilots or not. Heh heh.

I never had a single problem with the female pilots back in the day, especially in the Viper. That rascal was made for small people and you did not have to be a 200 pound gorilla to handle it just fine. But we in USAF didn't get females in fighters until 1995 or 96 or so. And the Navy restricted Miss Tammie to "training" outfits.

All that being said, the lady done good to get into fighters and then now for over twenty years as a custodian of more than a hundred SLF folks that depended on her to get them here and there.

No doubt the lady is getting the attention because she is a lady!!! So let her be a good example for anyone that wants to be a pilot and stop all the "diversity" emphasis. A good pilot is a good pilot.

Gums opines...

[aterpster]

Gota tellya, Bubba, but 26 years ago I would have been "interested" in Miss Tammie, with a buncha other folks, pilots or not. Heh heh.

Apparently, so was her husband, also a SWA captain. :D

[bandagunda]

Considering the gravity of this situation , 2 serious failures and memory actions accordingly plus a flap non normal checklist - landing with flap 5.

...........

Significant investigative effort should also be placed on examining the
procedures and why the airline has had a similar occurrence 2 years back .

Out .
Is it right that the investigation of (first incident) 2016 is yet incomplete, and no conclusions are published. There has been no AD issued in 2016 incident? Yes, CFM then issued an inspection SB, but there is no related AD.

[hunbet]

Preliminary report :

https://www.ntsb.gov/investigations/Pages/DCA18MA142.aspx

[JPJP]

Originally Posted by Lost in Saigon https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/607900-swa1380-diversion-kphl-after-engine-event-post10122798.html#post10122798)
I assume the un-named male First Officer was the Pilot Flying during the descent and initial approach, while Captain Tammie Jo Shults ran the checklist and the radio. (except when the FO responded to ATC clearing SWA1380 direct to Philadelphia)

On final, when they switched to the tower frequency, Captain Shults took over flying while the First Officer worked the radio.
(after landing the Captain went on the radio again)


Other way around - The PF would be working the radios, and the FO would be running the checklist. If the FO answered a radio call it may indicate that the CA was communicating with the FAs or making a PA. On approach the roles may return to normal, with the majority of checklists complete.

Obviously, it’s the CA perogative if she wants to run the checklist/manage.

To circle back to the answer to this question; from the investigation -

“The captain took over flying duties and the first officer began running emergency checklists. The captain requested a diversion from the air traffic controller;”

[PastTense]

Pilot and copilot are going to be on ABCs 20/20 Friday, May 11 at 10 p.m. ET.

Summary of the program with some information on what the pilot vs copilot was doing.

I don't think anyone in this thread mentioned the delay in communicating with flight attendants: "A few minutes before landing, the pilots were finally got in touch with the flight attendants, who informed them that there were injured passengers and that a window had shattered."

https://abcnews.go.com/US/pilots-safely-landed-southwest-flight-deadly-engine-failure/story?id=55041588

[lomapaseo]

PasstTense

Thanks for the link.

I was surprised about the person tense used in the wording. Most of it seemed to be attribital to the pilots until the section in quotes

"A few minutes before landing, the pilots were finally got in touch with the flight attendants, who informed them that there were injured passengers and that a window had shattered."

In my read this signifies an opinion by the writer that I do not share. Perhaps it would make more sense if the words used were only from the pilots or from the NTSB prelim summary

[Herod]

A good extract from the interview in today's London Times. "So long as you have altitude and ideas you are OK. We had both". Yep.

[gums]

Speed is life, but altitude is life insurance.

Gums sends...

[Airbubba]

Here's a re-creation of the event done by an Embry-Riddle prof in a CRJ sim. She demoes stickshaker, GPWS and other stuff on the single engine descent and approach.

https://news.erau.edu/headlines/erau-flight-simulator-instructors-reenact-emergency-landing-on-abcs-2020/

[Delight]

SLF Dumb Question; Why does the stickshaker go off? I thought that was for stall warning. Would an engine out while in the cruise reduce airspeed so quickly as to near stall speed?

[FIRESYSOK]

An engine failure at any altitude should not devolve into a stall. That performance would not pass an annual simulator check by a mile. I suspect the producers wanted more of a show. Scary lights, warbler, stick pusher, etc. At least I hope that’s what it was.

[RAT 5]

A known event. B737 family. >FL350. Engine failure in crz at night then developed into a stick shaker event very quickly. I suspect the startle factor and lack of experiencing such an event in the sim might have led the crew into focusing on the engine failure rather than ANC.

[Airbubba]

The plane was ferried to the boneyard at VCV today:

http://twitter.com/JenSchuld/status/1004834021858136064

[underfire]

Flaws in jet engine fan blades like one that cracked and broke loose in April, killing a Southwest Airlines Co. (https://www.bloomberg.com/quote/LUV:US) passenger, have been discovered on planes operated by several carriers, and the manufacturer is moving to further tighten inspections.

General Electric Co., part of a venture that makes the engines, found a cracked blade during post-accident inspections of another Southwest plane, and spotted four or five more in those of other airlines, Southwest Chief Operating Officer Michael Van de Ven said Thursday on a conference call to discuss earnings.

“We expect to formalize the interval in a new service bulletin that will be issued in coming days,” GE spokesman Perry Bradley said in a statement. Service bulletins are non-binding recommendations on maintenance, but are almost always made mandatory by aviation regulators.

Southwest has already cut the inspection interval for older engines almost in half, from 3,000 flights to 1,600, Chief Executive Officer Gary Kelly said in an interview.

https://www.bloomberg.com/news/articles/2018-07-26/southwest-boosts-inspections-of-engine-involved-in-fatal-failure?utm_source=yahoo&utm_medium=bd&utm_campaign=headline&cmpId=yhoo.headline&yptr=yahoo (https://www.bloomberg.com/news/articles/2018-07-26/southwest-boosts-inspections-of-engine-involved-in-fatal-failure?utm_source=yahoo&amp;utm_medium=bd&amp;utm_campaign=headline &amp;cmpId=yhoo.headline&amp;yptr=yahoo)

Here's a re-creation of the event done by an Embry-Riddle prof in a CRJ sim. She demoes stickshaker, GPWS and other stuff on the single engine descent and approach.

Why is the point to use a CRJ sim? a similar failure on a CRJ you would be looking at far dearer consequences.

[sardak]

The NTSB held an investigative hearing last week with witnessess from Southwest, Boeing, CFM and FAA. The public docket was also opened which has inteviews with the flight and cabin crews and passengers, CVR transcript and FDR data. The link to the hearing page, which in turn has a link to the docket, is https://www.ntsb.gov/news/events/Pages/2018-DCA18MA142-IH.aspx

[Mookiesurfs]

Airspeed, altitude, ideas. Any two and you’ll be ok.

[Zeffy]

NTSB Docket (https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=61786)

[sandos]

NTSB Docket (https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=61786)

I saw something interesting in the FDR factual report: the vibration values for Eng 1 are clearly higher than for 2 long before it goes boom. They go above (I presume unitless scale) the value of 1.0 on the graphs, when 2 is about 0.5. Can the engines warn themselves about high vibrations or is it up to the crew to look at the gauges? I know the manufacturers have very advanced algorithms to detect wear/maintenance needs and so on, but how clever is the onboard software?

Edit: I looked at the wrong graph. Apparently there is no large difference in magnitude between the engines... rather looks like Eng 1 vibration goes way down before it disintegrates. Very hard to tell with the scaling being that extreme for Eng 1. Looks like either the vibration went down to 0, or the rendering of the graph is not very good.

[lomapaseo]

Can the engines warn themselves about high vibrations or is it up to the crew to look at the gauges? I know the manufacturers have very advanced algorithms to detect wear/maintenance needs and so on, but how clever is the onboard software?

more like the ability of the detector and its mounting location to reliably detect (discriminate) all sources of vibration. We really don't want to introduce spurious unwarranted engine shutdowns, so we still rely on the pilot to use other senses as well.

[tdracer]

With a few notable exceptions, Boeing doesn't have any recommendations regarding high engine vibrations other than 'crew awareness'. There are other potential causes for engine vibrations other than imminent engine failure - e.g. ice accumulation on the fan/compressor blades (which can usually be addressed by temporarily increasing the engine power setting).
Even when the vibrations are the result of engine damage, you don't want the FADEC unilaterally shutting the engine down - the problem could easily affect multiple engines (e.g. birdstrike) and the last thing you want to do is do an auto-shutdown of all engines.
The one exception for high vibes that I recall was for the RB211-524 engine. After a couple of bearing failure related fan shaft fractures that culminated in uncontained engine failures, if the engine vibes exceeded some threshold the crew was instructed to shut it down.

[aterpster]

We really don't want to introduce spurious unwarranted engine shutdowns, so we still rely on the pilot to use other senses as well.
Especially at the ETP between Los Angeles and Honolulu.

[Roger_Murdock]

I took a gander at the CVR transcript from the docket, and I think it's a really interesting illustration of professionalism, competence, and humanity. The pilots apparently intended to pull the CVR breaker at some point after landing and either failed or couldn't find it (p.65,p.86). So there is a lot more than we usually get of the aftermath of an incident- including debriefing between the pilots and with with the union and ARFF. The CVR is not fully turned off until after the airplane is towed away.

They did have to skip a few checklist items, but in totality they acted efficiently to perform a safe landing. (Engine Fire and Engine Severe Damage checklists seem to have been completed to the best of their ability.) It seems that there was a lot of mutual understanding or non-verbal communication not captured on the CVR, which is interesting.

Given the situation they faced, which included 1. Uncontained engine failure, 2. Resultant control problems due to airflow changes, 3. Loss of half of their hydraulics, 4. Rapid depressurization, and 5. Severely injured passenger, I'd say they did a solid job.

At the beginning of the incident there's not much intelligible audio, possibly because of the crew masks.

Some things I noted:

They did not make contact with the cabin crew until about 12 minutes into the incident- they were focused on descending.

The captain decided to do flaps 5 landing because of possible control surface damage and controllability issues.

They knew pretty much right away that the passenger had died, and informed the airline within about 7 minutes of landing when they called dispatch.

p.67 - The FO gets annoyed when scheduling calls him and he tries to get them off the phone as soon as possible.

p.70 - The FO summarized the incident thusly to the union rep on the phone:

I think the engine blew up I think a fan blade pierced our window I think we had a rapid decompression because of that. that's what I think happened.

p.72 - GND wants to know if they suspect terrorism. FO says no, mechanical, 100%.

p.78-81 - The pilots debrief each other and try to get their story straight about skipping checklist items. Nothing nefarious here! The captain takes responsibility and says they FO shouldn't try to cover for her.
Captain: I just wanted to know you don't have to defend my skipping of some of the checklists to get on the ground.

[Zeffy]

https://www.reuters.com/article/us-southwest-airplane/u-s-safety-board-wants-boeing-to-redesign-737-ng-part-after-fatal-southwest-accident-idUSKBN1XT1EK

U.S. safety board wants Boeing to redesign 737 NG part after fatal Southwest accident


WASHINGTON (Reuters) - The U.S. National Transportation Safety Board on Tuesday called on Boeing Co (BA.N) to redesign the fan cowl structure on all 737 NG planes and retrofit existing planes after an April 2019 incident in which a woman was killed on a Southwest Airlines (LUV.N) plane after an engine failure caused by a fan blade.

The board said the U.S. Federal Aviation Administration should require Boeing to determine the fan blade impact location or locations on the engine fan case and redesign the structure to minimize the potential of a catastrophic failure. The board did not fault Boeing’s analysis in the mid-1990s when it developed the case.

Boeing and the FAA did not immediately comment.

NTSB Chairman Robert Sumwalt acknowledged the retrofit could be expensive.

“This accident underlines the vulnerability of the fan case to become separated when the fan blade detaches at a location that was not anticipated,” Sumwalt said after the hearing.

The NTSB did not call for the planes to be grounded and noted that airlines are now inspecting the fan blades on a more regular basis.

Jennifer Riordan of New Mexico, a 43-year-old Wells Fargo vice president and mother of two, was killed after the engine exploded and shattered a plane window on Flight 1380. She was the first person killed in a U.S. passenger airline accident since 2009.

The accident occurred 20 minutes into the flight when a fan blade fractured as a result of a fatigue crack on a Boeing 737-700 jet powered by two CFM International CFM56-7B engines after taking off from New York’s LaGuardia Airport. The plane, bound for Dallas, diverted to Philadelphia International Airport. Eight of the 144 passengers suffered minor injuries.

The NTSB had been investigating a 2016 engine failure on another Southwest 737-700 at the time of the fatal incident. The incidents in both flights were what is known as a “fan blade out” (FBO) event.

The board noted that there are 14,600 CFM56-7B engines in service with 356,000 fan blades on the Boeing planes, with 400 million flights over more than two decades and two reported engine failures.

Tammie Jo Shults, the flight’s captain, recounted in her book “Nerves of Steel” published last month, that the engine explosion felt “like we’ve been T-boned by a Mack truck.” She said that the 737-700 rolled to the left and pulled into a dive, but that she and the co-pilot were able to level off the plane.

The engine on the plane’s left side spewed bits of metal when it blew apart, shattering a window and causing rapid cabin depressurization, the NTSB said. In 2018, the NTSB said two passengers eventually pulled Riordan, who was buckled into her seat, back inside the plane.

CFM International, the engine manufacturer, is a transatlantic joint venture between General Electric Co (GE.N) and France’s Safran SA (SAF.PA).

Reporting by David Shepardson; Editing by Gerry Doyle, Alex Richardson and Dan Grebler

[Zeffy]

Presentations:

Board Meeting : Left Engine Failure and Subsequent Depressurization, Southwest Airlines Flight 1380, Boeing 737-7H4, N772SW (https://www.ntsb.gov/news/events/Pages/2019-DCA18MA142-BMG.aspx)

[Zeffy]

Abstract of Final Report (https://www.ntsb.gov/news/events/Documents/2019-DCA18MA142-BMG-abstract.pdf)

Recommendations

To the Federal Aviation Administration

1. Require Boeing to determine the critical fan blade impact location(s) on the CFM56-7B
engine fan case and redesign the fan cowl structure on all Boeing 737 next-generation
series airplanes to ensure the structural integrity of the fan cowl after a fan-blade-out event.

2. Once the actions requested in Safety Recommendation [1] are completed, require Boeing
to install the redesigned fan cowl structure on new-production 737 next-generation-series
airplanes.

3. Once the actions requested in Safety Recommendation [1] are completed, require operators
of Boeing 737 next-generation-series airplanes to retrofit their airplanes with the
redesigned fan cowl structure.

4. Expand the Title 14 Code of Federal Regulations Part 25 and 33 certification requirements
to mandate that airplane and engine manufacturers work collaboratively to (1) analyze all
critical fan blade impact locations for all engine operating conditions, the resulting fan
blade fragmentation, and the effects of the fan-blade-out-generated loads on the nacelle
structure and (2) develop a method to ensure that the analysis findings are fully accounted
for in the design of the nacelle structure and its components.

5. Develop and issue guidance on ways that air carriers can mitigate hazards to passengers
affected by an in-flight loss of seating capacity.

[Zeffy]

NTSB Board Meeting: Southwest Airlines Flight 1380 Investigation
https://youtu.be/gWx4TWrPji8

[jimjim1]

Abstract of Final Report (https://www.ntsb.gov/news/events/Documents/2019-DCA18MA142-BMG-abstract.pdf)

Final Report not yet published, to try to save anyone else the trouble of looking for it:-)

"NTSB staff is currently making final revisions to the report from which the attached conclusions and safety recommendations have been extracted."

[Zeffy]

https://www.cnbc.com/2019/11/19/ntsb-calls-on-boeing-to-redesign-some-737s-after-deadly-2018-southwest-accident.html

Boeing commits to NTSB safety fixes on thousands of 737 NG jets after deadly Southwest engine blast

Boeing on Tuesday said it plans to revamp parts for thousands of 737s after federal safety officials investigating last year’s deadly engine blast on Southwest Airlines flight called for a redesign that would better withstand engine failures in flight...

...Boeing said it commended the NTSB for its investigation and said it is “committed to working closely with the FAA, engine manufacturers, and industry stakeholders to implement enhancements that address the NTSB’s safety recommendations.”

It said “enhancements are being introduced” to inlet and fan cowls to improve “their ability to withstand an engine fan blade out event as well as to increase the overall capability of these structures.”

[SLF3]

So the engine nacelle won't contain a blade failure. Are the rudder cables on the 737 NG vulnerable to blade impact damage, or is that a Max specific issue?

[lomapaseo]

So the engine nacelle won't contain a blade failure. Are the rudder cables on the 737 NG vulnerable to blade impact damage, or is that a Max specific issue?

NO, nothing to do with the the recommendations at hand

[Takwis]

So the engine nacelle won't contain a blade failure. Are the rudder cables on the 737 NG vulnerable to blade impact damage, or is that a Max specific issue?

Yes, they are, to all models of 737. That may not be WHY Boeing is getting busy with the cowling issue, but the cables will be somewhat better protected if the cowling improvements work.

One issue is how FAA managers agreed during certification of the 737 MAX to give Boeing a pass on complying with a safety rule that requires more separation between duplicate sets of cables that control the jet’s rudder.This is to avoid the possibility that shrapnel from an uncontained engine blowout could sever all the cables and render the plane uncontrollable.The requirement was introduced when such a blowout caused the deadly 1989 crash of a United Airlines DC-10 in Sioux City, Iowa. The 737 has never been brought into line with the requirement, and when Boeing updated to the 737 MAX it argued once again that design “changes would be impractical” and expressed concern about the potential impact on “resources and program schedules,” according to documents submitted to the FAA. https://www.seattletimes.com/business/boeing-aerospace/new-questions-raised-on-safety-of-both-737-max-and-787-dreamliner/

[Zeffy]

New additions to the Docket (https://dms.ntsb.gov/pubdms/search/hitlist.cfm?sort=1&order=1&CurrentPage=1&EndRow=15&StartRow=1&docketID=61786&txtSearchT=):

​​​​​​1 Dec 05, 2019 Party Submission - SWA 14 pages
2 Dec 05, 2019 Party Submission - Collins 7 pages
3 Dec 05, 2019 Party Submission - CFM 29 pages
4 Dec 05, 2019 Party Submission - Boeing 21 pages

[Zeffy]

https://youtu.be/HDxcBWZUCTI

[tdracer]

Yes, they are, to all models of 737. That may not be WHY Boeing is getting busy with the cowling issue, but the cables will be somewhat better protected if the cowling improvements work.

https://www.seattletimes.com/business/boeing-aerospace/new-questions-raised-on-safety-of-both-737-max-and-787-dreamliner/

No, the control cable issue isn't fan blades and their associated debris. The cable issue is for an uncontained disc failure - which by definition won't be contained by the nacelle or engine structure (Where will a 1/3 fan disc go? Anywhere it wants to :eek:).
The issue at hand is the failure of the inlet after the Fan Blade Out event. The containment ring worked as intended and contained all the high energy blade debris. However some of the low energy debris traveled forward and damaged the inlet (which didn't happen when they did the FBO test ~25 years ago), combined with higher than expected imbalance loads caused the inlet structure to fail. The damage to the fuselage was caused by the inlet, not the fan blade debris. Big parts departing the engine are a bit no-no since they can cause major damage to other parts of the airframe (the tail being the big concern):
the stresses in the fan cowl were greater than those calculated in the certification analyses. Since the time that the CFM56-7B engine and the Boeing 737-700 airplane were certificated (in December 1996 and December 1997, respectively), new technologies and analytical methods have been developed that will better predict the interaction of the engine and airframe during an FBO event and the response of the inlet, fan cowl, and associated airplane structures.

[Dave Therhino]

... The damage to the fuselage was caused by the inlet, not the fan blade debris. ...:

You are correct it was not fan blade fragments that broke the window. However, the window was actually struck by a section of the fan cowl door that held the heavy latch structure. When the fan blade released, it happened to hit at a clock position that gave a huge force and displacement to the bottom of the fan case. There is an unusual latch beam support connection to the fan case on this engine due to the flat bottom of the nacelle shape. The support is intended to keep the fan cowl doors tightly up against the engine. When the case in this area was driven outward, it directly transmitted load to the doors and latches and broke the doors open. A piece from the bottom latch end of one of the doors was slung at the fuselage and struck the window area, breaking the one window.

[lomapaseo]

You are correct it was not fan blade fragments that broke the window. However, the window was actually struck by a section of the fan cowl door that held the heavy latch structure. When the fan blade released, it happened to hit at a clock position that gave a huge force and displacement to the bottom of the fan case. There is an unusual latch beam support connection to the fan case on this engine due to the flat bottom of the nacelle shape. The support is intended to keep the fan cowl doors tightly up against the engine. When the case in this area was driven outward, it directly transmitted load to the doors and latches and broke the doors open. A piece from the bottom latch end of one of the doors was slung at the fuselage and struck the window area, breaking the one window.

Taken together with tdracerr post above, the individual details in the subject event are obviously repeatable for a number of reasons not all related to a CFM56 Fan blade failure. Thus the corrective actions as recommended are only minimizations of combinations. Taken in total the end result in this case is very improbable to re-occur. No doubt the manufacturers proposed actions are positive, but in the grand scheme of flight safety are not really news worthy.

[Dave Therhino]

Possibly the worst threat posed by a fan blade failure with an inlet separation from a probabilistic standpoint is fuel exhaustion on an extended range flight. If a fan blade fails (which often depressurizes the fuselage due to intermediate fragments) and the inlet comes off during a step climb halfway between the West Coast and Hawaii, there is not enough fuel on board to make land due to the high drag of the failed nacelle.

[lomapaseo]

Possibly the worst threat posed by a fan blade failure with an inlet separation from a probabilistic standpoint is fuel exhaustion on an extended range flight. If a fan blade fails (which often depressurizes the fuselage due to intermediate fragments) and the inlet comes off during a step climb halfway between the West Coast and Hawaii, there is not enough fuel on board to make land due to the high drag of the failed nacelle.

Of all the non-contained fan blade fragments(only) that pierced the fuselage I don't recall one where pressurization was lost. A whistling sound was reported though

Losing an inlet cowl might also result in less drag. At any rate it has certainly happened before even with large fan engines and no control problems reported by the pilot

[Dave Therhino]

Both the recent Pensacola and Philadelphia 737 CFM56-7B fan blade failures that caused inlet separations depressurized the fuselage. The skin on the 737 is quite a bit thinner than the skin of the larger airplanes. The pilot in the Philadelphia event reported significant control challenges. The drag study was done and the drag of a nacelle with the inlet missing is significantly greater than that of an intact nacelle with a windmilling engine. The critical scenario for setting ETOPS fuel reserves on a West Coast to Hawaii flight is an engine failure that causes depressurization at the critical point (equal time point). That required fuel is calculated based on the drag of an intact nacelle.

[infrequentflyer789]

There is an unusual latch beam support connection to the fan case on this engine due to the flat bottom of the nacelle shape.

Thank you for some illuminating and interesting posts. Since the unusual flattened nacelle shape is to fit the engine under the wing, are we to conclude then that this is another incident that is actually down to the short legs of the 737 and the desire to not redesign them for cost/ease-of-certification reasons?

[lomapaseo]

Both the recent Pensacola and Philadelphia 737 CFM56-7B fan blade failures that caused inlet separations depressurized the fuselage. The skin on the 737 is quite a bit thinner than the skin of the larger airplanes. The pilot in the Philadelphia event reported significant control challenges. The drag study was done and the drag of a nacelle with the inlet missing is significantly greater than that of an intact nacelle with a windmilling engine. The critical scenario for setting ETOPS fuel reserves on a West Coast to Hawaii flight is an engine failure that causes depressurization at the critical point (equal time point). That required fuel is calculated based on the drag of an intact nacelle.

You are mixing in events that have released more than fan blades that resulted in loss of pressurization

[Dave Therhino]

In the Pensacola event I believe it was a fan blade fragment that depressurized the airplane.

I was simply pointing out that, while the fuel load required for an engine failure that depressurizes the airplane is covered by the ETOPS fuel reserve rules, the fuel required if you add drag from a nacelle with a severely damaged or missing inlet is not covered.

[lomapaseo]

In the Pensacola event I believe it was a fan blade fragment that depressurized the airplane.

I was simply pointing out that, while the fuel load required for an engine failure that depressurizes the airplane is covered by the ETOPS fuel reserve rules, the fuel required if you add drag from a nacelle with a severely damaged or missing inlet is not covered.

Ir was a disk uncontainment along with its blades, quite a bit more robust than a fan blade release. A fan blade release simply doesn't have the energy to make a big hole in a pressurized cabin.

[OldnGrounded]

Ir was a disk uncontainment along with its blades, quite a bit more robust than a fan blade release. A fan blade release simply doesn't have the energy to make a big hole in a pressurized cabin.

If the reference is to SW 3472, it seems to have been a fan blade, unless the final report, which I can't find, discovered a disk failure not seen early in the investigation, which seems unlikely.

Investigative Update (SW 3472) (https://www.ntsb.gov/news/press-releases/Pages/PR20160912.aspx)

Initial findings from the engine examination include:

One fan blade separated from the fan disk during the accident flight and
The root of the separated fan blade remained in the fan hub; however, the remainder of the blade was not recovered.

Initial findings from the metallurgical examination conducted in the NTSB Materials Laboratory include:

The fracture surface of the missing blade showed curving crack arrest lines consistent with fatigue crack growth. The fatigue crack region was 1.14-inches long and 0.217-inch deep,
The center of the fatigue origin area was about 2.1 inches aft of the forward face of the blade root. No surface or material anomalies were noted during an examination of the fatigue crack origin using scanning electron microscopy and energy-dispersive x-ray spectroscopy, and
The blades are manufactured of a titanium alloy and the root contact face is coated with a copper-nickel-indium alloy.

[Manual Pitch Trim]

A really brilliant work example of why CRM works and why reduced crew operations would be unsafe and unnecessarily riskier. Reduced crew and single pilot operations throw mud and are an insult on the years of proven success of CRM in a severe catastrophic event.

The proof here is in the pudding.

Looking at this accident why would you as a passengerboard a aircraft with only 1 pilot?

The succseful result would not be the same.

[fdr]

In the Pensacola event I believe it was a fan blade fragment that depressurized the airplane.

I was simply pointing out that, while the fuel load required for an engine failure that depressurizes the airplane is covered by the ETOPS fuel reserve rules, the fuel required if you add drag from a nacelle with a severely damaged or missing inlet is not covered.

Dave's point is important.
The fuel policy of the operator covers various possible failure events, but not all.
Fuel policies do not cover any fundamental change to the drag count of the aircraft, other than a windmilling fan. There is no adjustments for the loss of the cowl, opening of the cowl, deflection of a slat upwards into the flow, major birdstrike causing loss of radome etc. Most of these have occurred, and fortunately, the drag counts have not been enough on the day to cause a deficit on the fuel side, but they all have the potential to impact the flight dynamics and control authority of the aircraft.
We are dismayed routinely by what messes the crews can get up to, as in recent oddities with upsets, low-level scenics in B777s, etc, when the bits come off the plane it is up to a pilot to work out how to make that fly if it is possible. Occasionally it is not, or the crew don't get the time to sort it out. UAL232, UAL 811, QF32, QF72, etc, the crews were able to be effective. Both of the SWA fan failures, the one into Pensacola and the more recent one, as well as the B777 fan separation, are examples of crews dealing with the problem. Sully's swim is also, and he highlights a simple truth; what else do you expect the pilot to do? Pilots are going to be the first on the accident scene... but, the training and experience that underlies their day-to-day driving provides the basis for contingent capabilities. On the other hand, the USBangla Dash 400 at Katmandu kind of sets the other end of the spectrum.
Computerizing aircraft to reduce the human input comes with it's own certainties of failures and ensures that the final recovery opportunities of a device that has the potential to develop creative solutions is available, even with its fallibilities.

Passengers will opt to go fly with one or no pilots if it is going to be a dollar less out of their pocket. If the HAL 9000 goes feral with them on board, they will complain about the injustice all the way to impact, but then, so would the passengers in the A320 into the alps, and the B737 into Guangdong province... :rolleyes:

[tdracer]

Pending AD to strengthen the Nacelle Structure after two Southwest Fan Blade Out events that caused the inlet to depart (one fatality):
All Boeing 737 NG To Have Redesigned Engine Nacelles Following Deadly Southwest Incident (msn.com) (https://www.msn.com/en-us/travel/news/all-boeing-737-ng-to-have-redesigned-engine-nacelles-following-deadly-southwest-incident/ar-AA1lrqdh?ocid=msedgntp&pc=HCTS&cvid=2ceda378e6ea4323bbce5f11876dc074&ei=10)

The project was launched in 2019, following the conclusion of the investigation into a 2018 Southwest Airlines (https://simpleflying.com/tag/southwest-airlines/?utm_source=syndication) accident that left one passenger dead and eight injured. The engine cowling on the Boeing 737-700 was damaged following an in-flight failure, with fragments of the damaged nacelle piercing the fuselage and causing an explosive depressurization. A similar, non-fatal accident was also recorded by Southwest Airlines two years prior when debris from the engine cowl punctured part of the fuselage.

[BFSGrad]

$7,650 per aircraft? The decimal place seems to be at least one notch out of position.

[tdracer]

$7,650 per aircraft? The decimal place seems to be at least one notch out of position.
Yea, I found that number curious at best - especially since they're estimating 90 hours labor/aircraft.
Having commented on a few proposed ADs over the years (one of which had a whopper of an error in it), I suspect they'll get more than a little feedback on that part.

[DaveReidUK]

$7,650 per aircraft? The decimal place seems to be at least one notch out of position.

No, that's a misreading of the AD. The above is the estimated average admin cost per operator for making the required revisions to its maintenance/inspection programme. It doesn't cover either labour or materials for the actual inspection or for remedial work on the aircraft (if required).

[Jhieminga]

The FAA page here about this AD (if I've got the correct one): https://www.federalregister.gov/documents/2023/12/12/2023-27100/airworthiness-directives-the-boeing-company-airplanes lists $13,300 for the modification and just shy of $3000 for fastener replacement.