CH47A wrote:

What are the thoughts on this simply being a case of a ground maintenance individual and his/her boss not properly doing their job?

And I hope to be excused for using the vocabulary simply.

EDIT: An apology for missing sebring's post just a bit above. Seems somebody else also is thinking that some sort of human ground maintenance situation may be a factor here.

It split in half, right where somebody performed a hot bond on the top of the cowl. You can clearly see the repair.

Interesting on the tower tape that the crew in running the checklist states that the cabin altitude is "uncontrollable", meaning a confirmation of depressurization. Also, the tower keeps asking the incident aircraft to state altitude, whereupon one pilot finally asks the tower whether they don't have transponder for 3472. "Roger, sir." The pilot makes a sardonic comment about just another thing not working on this aircraft. Interesting why the transponder wouldn't work (or at least the altitude information wouldn't transmit).

wjcandee wrote:

Interesting on the tower tape that the crew in running the checklist states that the cabin altitude is "uncontrollable", meaning a confirmation of depressurization. Also, the tower keeps asking the incident aircraft to state altitude, whereupon one pilot finally asks the tower whether they don't have transponder for 3472. "Roger, sir." The pilot makes a sardonic comment about just another thing not working on this aircraft. Interesting why the transponder wouldn't work (or at least the altitude information wouldn't transmit).

That sounds like atc only wanting to confirm their readings were still correct.

So just saw a TV news story on this…engine explodes, passengers 'terrified' and 'think they are about to die' oxygen masks on but of course decide to take selfies and post to social media.

rfields5421 wrote:

Nothing in the pictures looks like a failure in the engine.

Not directly, no. But I'm sure that the engine ingested some debris and wound up failing secondary to the loss of the inlet assembly.

zeke wrote:

Referring to the first photo in the OP.

Anyone car to comment why the latches look undone ?

Why is the inspection panel open

It is am overpressure relief panel. The latches will open with high pressure under the panel. Maybe a duct failure started all this?

I think the wing root, fuselage and tail damage can be explained by aerodynamic forces opening the cowling like the petals of a flower, hinging on what's left of the nacelle to give the debris plenty sideways acceleration to slam into the fuselage.

What really baffles me is the nicked winglet on the other side of the engine.

Did they have to shut down the engine with damage and land with just one ?

wstakl wrote:

So just saw a TV news story on this…engine explodes, passengers 'terrified' and 'think they are about to die' oxygen masks on but of course decide to take selfies and post to social media.

Once they'd put their masks on they were along for the ride. What else to do?

Hello all,

This could have gotten ugly real fast. The flight crew probably heard/felt the loud bang just before the cabin depressurized and the engine giving them bad indications all in a very short time. The crew reacted, went into emergency decent and ultimately got everyone down on the ground un-injured. If a blade[s] let go and pierced the fuselage it would have been worse. Listening to them during the emergency, I hear calm professionals working the problem and they should be commended. The cabin crew probably did their best to calm the pax but looking out the window, it was more difficult after seeing the damage.

The news media sucks with their inacurate news-gloom stories of an engine exploding, or an engine falling off so they can get writing the mostly inaccurate 'tarmac' in their story lines.
I'm glad there were no injuries. Two things i'd like to see: the look on the pilots faces when they first saw the damage on their aircraft and the history of that cowl and if repaired recently and if WN did it themselves or sourced it out.

I tip my cap and salute them for doing it extremely well under trying circumstances. Thank you to the pilots....

LightningZ71 wrote:

It's an Elon Musk / SpaceX term. He uses it to describe the process by which a rocket annihilates itself when it hits the ground with excess velocity, or an uncontained rapid burn of combustible material leads to an over-pressure situation inside of a space craft (it blows up).

It's a much older term than that. I remember it being used in the Kerbal Space Program community years before Musk used it. And it was old then. Pretty sure it's an old engineering term that's used to make and incident sound better than "It blew up/broke apart." Otherwise people get antsy.

Props to the original engineers, builders, and the crew for getting everyone back safe and sound.

The "say altitude" calls from controllers were pretty frequent. I does appear they were in the dark about altitude. And thus, this aircraft may indeed have had problems squawking.

This really does seem to have been a pretty serious situation. Not second guessing here, but I am surprised the crew wanted to be vectored to 17 for the ILS instead of quickly going into runway 8. If the turn to the north explains needing to shed altitude, that is a reasonable explanation, but extra time aloft seems odd considering 8/17 are almost identical strips, emergency first assumed 8, and winds were not a factor in runway selection.

Looks liks an overpressure event of the anti-ice system. Large repair on the cowling (could be additional delimitation in area), high pressure valve failure or duct/joint burst over pressuring the inlet. The bang could be the duct blow out which could/would lead to de-pressureation especially if the shutoff valve is damaged from debris. Smell in cabin is a good indication duct rupture as well. The fan appears to be spinning in one of the pictures which would lead to believe it was not fan blade issue.

Great when training gets everyone home safe(minus underwear change) Good job Southwest pilots, ATC, Emergency services in Penscola.

The anti icing overpressure as indicated by the open access panels could have occurred after the cowl separation. The bleed air supply tube appears to be kinked in a way that would have sealed it off and caused a spike in pressure upstream in the bleed air system. Highly speculative but I'd put a bet on the failure originating in a non pressure related failure of the cowl/housing. Issues with the bleed air were result of the initial failure not a cause.

It would be helpful to know how quickly separation occurred. Was it one explosive failure of the entire cowl or a small separation that cascaded into what is shown in the photos? I recognize that both failure modes could appear to the human eye as the same thing given how quickly the cowl could have disintegrated from a small failure due to the aerodynamic pressure in place at the time.

I just listed to the ATC recording and the part were the pilot comments that the faulty transponder is, "just another thing wrong with the plane." I'm wondering where the antenna for this is on the 737-700? Could the piece of debris that hit the vertical stab have taken out an antenna as well?

Do southwest pilots do a walkaround before every flight where the pilots could have noticed loose fasteners? I know other airlines are required to on every flight but somehow I remember that southwest did not.

kraz911 wrote:

Hello all,

This could have gotten ugly real fast. The flight crew probably heard/felt the loud bang just before the cabin depressurized and the engine giving them bad indications all in a very short time. The crew reacted, went into emergency decent and ultimately got everyone down on the ground un-injured. If a blade[s] let go and pierced the fuselage it would have been worse.

A blade isn't supposed to be able to do that. Turbine disks, on the other hand, can do that, and have, several times.

wstakl wrote:

So just saw a TV news story on this…engine explodes, passengers 'terrified' and 'think they are about to die' oxygen masks on but of course decide to take selfies and post to social media.

But i do hope that the passengers (and everyone else) realize that they (the passengers and crew) were travelling in one of the safest modern transportation machines known to man. With so much emhpasis on redundant safety features, so much emphasis on training & other operational procedures designed with safety in mind..becaus of which not one fatality of injury in this incident. Kudos to modern aviation! Contrast this with how there can be multiple fatalities due to a simple blown tire at highway speeds on a bus or an SUV.

fr8mech wrote:

Just spit-balling here, but I wonder if this couldn't be a pneumatic over-pressure event.

The blown open service doors indicative of such an event.

It's clearly an inlet cowl separation, but what if it was from an internal event (over-pressure of the inlet TAI system) vs. an external event, that caused the cowl to fail in a localized area and then aerodynamic forces took over and tore the inlet apart and off the airframe. Separation in stages can easily cause the widespread damage we see.

Now, in my almost 30 years in the industry, I've never quite seen an inlet fail quite so bad.

Have to agree on most points with you, especially never seeing anything like this. But would the anti-ice nose cowl system be able to do that ? After entering the nose cowl the hot engine bleed air comes out of the piccolo tubes heating the LE of the nose cowl and then blows overboard through that vent at the bottom of the cowl. Did the vent become clogged ? How ? What is intriguing to me, is in the photo taken inflight, this one,



the big long patch of shiny metal on top of whats left of the nose cowl with the red sealant around it's perimeter. Do not remember seeing that in nose cowls. Looks to be a repair possibly, and the tear goes right along the edge of that area. and the tear along that area is pretty linear. The rest of the nose cowl that is left, the edge is jagged. A bad crack not caught ? Or was there a failure of the TAI system on #1 engine. The regulator on the TAI is supposed to keep pressure below 50psi. Did the TAI pressure switch illuminata before this event showing that TAI duct pressure was above 65psi ?

Pieces of that nose cowl as it came apart interrupting the airflow at that flight level could have stalled the compressor overpressurizing the bleeds, catching the VBVs and VSVs off guard, and bleed lines causing all those access panels to blow open. Will be interesting to see what the NTSB will find out in the investigation.

Never heard of anything like this before. Never thought you would have a cowl incident like this either. Wow.

I'm surprised the strake/chine didn't get ripped off too. Obviously the debris moved around it, and its fasteners held fast.

Oops, didn't see some of the spot on comments on page 2. Also, in this photo, there is another suspect shiny metal area where the nose cowl tore off linear to the edge of that shiny area. So it seems like two areas of repairs that look suspect. Area is near the bottom of the inlet in this photo, ending about the 8 o'clock position in the inlet....bad repairs or too many performed ? Hope not,...

That area in the photo above looks like the acoustical material just came apart from the nose cowl structure, maybe not a repair.

b747400erf wrote:

wjcandee wrote:

Interesting on the tower tape that the crew in running the checklist states that the cabin altitude is "uncontrollable", meaning a confirmation of depressurization. Also, the tower keeps asking the incident aircraft to state altitude, whereupon one pilot finally asks the tower whether they don't have transponder for 3472. "Roger, sir." The pilot makes a sardonic comment about just another thing not working on this aircraft. Interesting why the transponder wouldn't work (or at least the altitude information wouldn't transmit).

That sounds like atc only wanting to confirm their readings were still correct.

Well, at first it seemed so, but when the crew noted the frequency of altitude requests and asked ATC whether they didn't have transponder data for the aircraft, and ATC responds in the affirmative, I'm pretty sure it means that ATC didn't have altitude transponder data for the aircraft.

Where will they repair this jet?

I've only seen this one other time and it was due ti a compressor stall when a variable vane ring
failed NOBODY id going to know until the engine has been removed and torn down though the Pylon will require a major inspection.

This adds up to the Aloha Airlines Flight 243 to show how the Boeing 737 is a sturdy design. The only shortcoming is the fact that it is losing gracefully to the A32s.

strfyr51 wrote:

I've only seen this one other time and it was due ti a compressor stall when a variable vane ring
failed NOBODY id going to know until the engine has been removed and torn down though the Pylon will require a major inspection.

Do you remember the details of this incident? airline? aircraft? This sounds very interesting...

I noticed the passenger pictures show the strake separating several inches before the aircraft reached the runway. Had the sheet metal on the bottom of the engine separated with the gear down that landing would have been far more interesting.

Long time lurker first time poster. I can shed light on whatever I know on this. The aircraft will be repaired at PNS. A team was dispatched from DAL. No information on recent maintenance due to lockout.

As for the damages. Debris landed in the gulf. Engine in the in air shot is windmilling. I can check a cowl soon for the plate as that does look unfamiliar which leaves me to believe it was an outsourced cowl.

What we do know is that there is a blade missing.

zeke wrote:

Referring to the first photo in the OP.

Anyone car to comment why the latches look undone ?

Why is the inspection panel open

Occasionally panels like that on engines come open inflight for various reasons (not properly latched, latches loose, etc) just because of the dynamics of the engine. With whatever went on in front of the panel it's not unreasonable that the forces in play would effect the panel causing it to open. I once ingested an engine side panel similar to that when it came open during reverse testing on a 757.

Ceamajay wrote:

Judging from the window pattern, that gash looks to be about six inches from the left elbow of the lucky occupant of seat 8A. Even on WN I'd say that entitles him or her to a complimentary alcoholic beverage.

And a voucher for dry cleaning.

Ceamajay wrote:

(It's good that we can laugh about it. It would appear that the flight crew, and those parts of the aircraft which remained attached, performed their respective duties to perfection.)

Indeed.

strfyr51 wrote:

I've only seen this one other time and it was due ti a compressor stall when a variable vane ring
failed NOBODY id going to know until the engine has been removed and torn down though the Pylon will require a major inspection.

Can the pylon stay on-wing for that inspection? Even when scrapping 737s the engine pylons usually remain in place (can't think of a time I've ever seen one dropped) so I assume removing it is a major job.

What’s the operating pressure and max. design pressure of the engine cowl lip TAI chamber? Is there a failed operating system transient relative to the 5th stage and 9th stage extraction system/valves which could result in an overpressure condition in the engine cowl lip TAI chamber? Obviously metallurgical issues with the materials in the internal cowl area could also result in sudden failure under (bleed) pressurized conditions, as well as any past maintenance, etc. repairs completed in the cowl internal pressurized area.

I bet the pylon is ok. Engine change, new fan cowls, Inlet duct, and repairs to the fuselage and leading edges. The fuselage repairs might take the longest. A lot of the others are just swap out fixes. None of it is cheap, but nothing in aviation is. The real question is why did it happen?

LightningZ71 wrote:

It's an Elon Musk / SpaceX term. He uses it to describe the process by which a rocket annihilates itself when it hits the ground with excess velocity, or an uncontained rapid burn of combustible material leads to an over-pressure situation inside of a space craft (it blows up).

"Rapid unscheduled disassembly" long predates Elon Musk's entry into the space business.

I haven't been able to trace back the ultimate origin of the phrase, but I'm under the impression it was coined during the Apollo program. At a minimum, here's a 1972 source with the closely related term "catastrophic self-disassembly" (page 123), and the specific quote there suggests the term was already well-circulated in the spaceflight community:
http://library.sciencemadness.org/libra ... nition.pdf

Here also is a 1981 book using the effectively identical phrase "Rapid, unintended disassembly."
https://books.google.com/books?id=Weg1W ... et&f=false

These terms are apt anytime you want to understate a dramatic failure, especially explosions.

The NTSB is investigating. I've not found any report from NTSB yet - but this information comes from an Aviation Week article and indicates no damage to rotating parts of the engine. They do not attribute this as a quote, so I can't speak to it's accuracy.


"Given the absence of evidence of damage to the fan stage and the intact fan case flange, it is likely the U.S. National Transportation Safety Board (NTSB) investigation will focus initially on the inlet cowl mounting structure and potential failures of the few systems that are located within it. Prime suspects are likely to include an overpressure of the inlet anti-ice system, possibly due to a TAI valve failure, a duct or vent failure in the pressurization system itself, or a mechanical failure of the fasteners. However the root cause and failure sequence could also be difficult to identify given the impact of air loads on the structure and the accelerated break-up this force would cause."

http://aviationweek.com/commercial-avia ... cdd546fd42

As stated in an earlier post the engine is missing a fan blade. IMHO this type of damage along with ithe resulting imbalance and vibration caused the fan cowl to disinegrate leading to the other damages to the airframe. Now it is up to the NTSB and others to find out why.

iamlucky13 wrote:

LightningZ71 wrote:

It's an Elon Musk / SpaceX term. He uses it to describe the process by which a rocket annihilates itself when it hits the ground with excess velocity, or an uncontained rapid burn of combustible material leads to an over-pressure situation inside of a space craft (it blows up).

"Rapid unscheduled disassembly" long predates Elon Musk's entry into the space business.

I haven't been able to trace back the ultimate origin of the phrase, but I'm under the impression it was coined during the Apollo program. At a minimum, here's a 1972 source with the closely related term "catastrophic self-disassembly" (page 123), and the specific quote there suggests the term was already well-circulated in the spaceflight community:
http://library.sciencemadness.org/libra ... nition.pdf

Here also is a 1981 book using the effectively identical phrase "Rapid, unintended disassembly."
https://books.google.com/books?id=Weg1W ... et&f=false

These terms are apt anytime you want to understate a dramatic failure, especially explosions.

Disassembly, whether "scheduled" or "unscheduled", would seem to imply that you can reassemble the components and make it work again.

freakyrat wrote:

As stated in an earlier post the engine is missing a fan blade. IMHO this type of damage along with ithe resulting imbalance and vibration caused the fan cowl to disinegrate leading to the other damages to the airframe. Now it is up to the NTSB and others to find out why.

Yet the NTSB is quoted in the post above you that there is no damage to the fan or shroud. Which one is correct ?

Spacepope wrote:

freakyrat wrote:

As stated in an earlier post the engine is missing a fan blade. IMHO this type of damage along with ithe resulting imbalance and vibration caused the fan cowl to disinegrate leading to the other damages to the airframe. Now it is up to the NTSB and others to find out why.

Yet the NTSB is quoted in the post above you that there is no damage to the fan or shroud. Which one is correct ?

If you read the post you are referring to, it states that the ntsb has yet to make a formal comment or whatever it says... whoever is saying that the fan blades and shroud are intact is from aviation week, not the ntsb. It also states that the person from avweek doesn't want to be quoted... which means they are full of bologna or doesn't actually know what is going on. I've been in contact with a SWA mechanic who confirmed a fan blade is missing, You just cant see it in the pictures. We'll see who's right, Avweek or my sources, should be interesting.

CBW wrote:

If you read the post you are referring to, it states that the ntsb has yet to make a formal comment or whatever it says... whoever is saying that the fan blades and shroud are intact is from aviation week, not the ntsb. It also states that the person from avweek doesn't want to be quoted... which means they are full of bologna or doesn't actually know what is going on. I've been in contact with a SWA mechanic who confirmed a fan blade is missing, You just cant see it in the pictures. We'll see who's right, Avweek or my sources, should be interesting.

1) Just because someone won't/can't go on record does not mean they are full of s***. In all likelihood the company said shut up to their employees on the project and let the PR dept handle it. They would probably get badly reprimanded if the company discovered they let out info like that.

2) If you want to get into a credibility match you will lose, because think about what you are saying:
Av Week is not credible because they are repeating info from an anonymous source (anonymous to everyone but the author), but I (anonymous person on a fan forum) am credible because my source is legitimate (even though it's again anonymous to everyone but the author).

Lastly, I would be very much interested in finding out if a fan blade is missing because loosing one with the engine running is a very violent event at any speed. So for it to loose a blade it either happened after shutdown or there is is really there must be cool physics going on to allow the fan to still look normal afterwards. Pretty much we wont know until the official report comes out

I'm sure the NTSB will make the pictures of the fan assembly available with their final report. CBW and thebig1 are correct there is a fan blade missing.

Erebus wrote:

iamlucky13 wrote:

"Rapid unscheduled disassembly" long predates Elon Musk's entry into the space business.

Disassembly, whether "scheduled" or "unscheduled", would seem to imply that you can reassemble the components and make it work again.

Yes, that's part of the joke.

Erebus wrote:

Disassembly, whether "scheduled" or "unscheduled", would seem to imply that you can reassemble the components and make it work again.

It really just depends on how much work you want to put on fixing up the parts..

I mean you might have to melt them down and re-smelt them......

USAirKid wrote:

Erebus wrote:

Disassembly, whether "scheduled" or "unscheduled", would seem to imply that you can reassemble the components and make it work again.

It really just depends on how much work you want to put on fixing up the parts..

I mean you might have to melt them down and re-smelt them......

This is probably the closest attempt I've seen...a sloppy one nevertheless.

freakyrat wrote:

As stated in an earlier post the engine is missing a fan blade. IMHO this type of damage along with ithe resulting imbalance and vibration caused the fan cowl to disinegrate leading to the other damages to the airframe. Now it is up to the NTSB and others to find out why.

if a fan blade departing was an initiator of the event, yes .... don't forget there's also an unknown about of debris that likely went through that engine, and any of that could easily have caused a blade to fail.

litz, You brought up a good point and we will just have to see what the NTSB determines initiated the event.

Hi all, my husband was on this flight and we've been following this thread to try and learn more about the technical aspect of what happened. Thank goodness for the educated responses that we found here The NTSB initial report came out today, curious to hear what you think!

http://www.cincinnati.com/story/money/2 ... /90274892/

Here is a link to the preliminary NTSB report on the incident just released on another site. The blade did fracture and now that the NTSB has made it's prelimanry findings known and they say the same thing I can say that the missing blade or ingested debris also took out chunks of metal out of two adjacent blades to the left of the missing blade as you would look at the fan creating the imbalance and possibly resulted in the cowl failure. This was also one of the earliest CFM56 engines manufactured for the 700 series jet.

http://atwonline.com/safety/fan-blade-m ... ne-failure

Here's the link to the NTSB press release itself, in case anyone missed it:

http://www.ntsb.gov/news/press-releases ... 60912.aspx

It will be very interesting to hear the full story of what took place when the investigation is completed!

Best,

OMP777X

So there is a fan blade missing and it is an uncontained engine failure.