AA B757 Exp. Decompression, FL310 due 1' x 2' hole in fuselage

[Clipper811]

All safe.

A/C with approx 60,000 hours had a decompression on flight 1640; MIA-BOS on Oct. 26th.
A 1 foot by 2 foot piece of the fuselage skin peeled back inflight causing explosive decompression at FL310.

Anyone have pics?

[tailstrikecharles]

May as well use this

Y9VegJ3n8vs

http://twitpic.com/show/thumb/a9vk8.jpg

Once you've seen some peeled back skin, you've seen em all
(unless you're Jewish)

[repariit]

"A/C with approx 60,000 hours had a decompression on flight 1640"

If so, something might have been missed on a couple of D-Checks. Anybody know what the disposition of the SWA incident was?

[411A]

Aft fuselage crown skin, perhaps?
IF so, seems a Boeing trouble prone area...even from the 707 days.

[BRE]

Isn't that because some fuselage sections from the 707 were never changed in any of the narrowbodies?

[411A]

Similar construction technique.
Initially, with some 707's, fuselage skin cracking was noticed, just above the aft door, on the fuselage crown.
External straps were fitted, for a maximum of 2500 cycles, then reskinning was accomplished.
This was a problem with the forward fuselage crown skin as well, but not quite so severe.
As I recall, heavier skins were then used on the -320B/C models.

[Green Guard]

Anybody know what the disposition of the SWA incident was?

I don't...please write more if you know.

[Bruce Wayne]

any press reports yet quoting the usual..

"..thought we were going to die.."

"...crash landed.."

"...narrowly missing a school/hospital/orphanage.."

... i could do with a laugh this morning !

[Agaricus bisporus]

Anybody know what the disposition of the SWA incident was?

Anyone know what "disposition" means in relation to an aeroplane incident?

I assume it's a transatlantic expression - it means nothing to us in Europe and the dictionary gives no help...

[411A]

Anyone know what "disposition" means in relation to an aeroplane incident?


Final outcome....IE: the end result.:rolleyes:

[Saintsman]

any press reports yet quoting the usual..

"..thought we were going to die.."

"...crash landed.."

"...narrowly missing a school/hospital/orphanage.."

... i could do with a laugh this morning !

Surely it should have sucked half the passengers out.....

[2 Whites 2 Reds]

As it was an AA flight I doubt any American will be brave enough to suggest they could fit through a 1ft x 2ft hole, last AA flight I was on many of them on board were lucky to get through the bloody door!!! :E

[VFR750]

HI
Not a frequent poster, but curious about this one

if a rotund person of any nationality happened to get sucked or pushed, the latter being more technically correct i guess, and they plugged up the hole, what are the implications of the "fluid hammer" effect of all the air rushing towards the hole, then having no where to escape to? could it cause a catastrophic failure of the structure?

many thanks

Neil Byrne

[Willit Run]

VFR 750,

Air is compressible, so no hammer effect like hydraulics. And, there are a couple things called "pressure relief valves" to prevent (whatelse) over pressure.

Holes in fuselages are fairly rare, but they do happen, and the structures engineers have done a good job designing them , so when they do fail, the damage doesn't do what the movies think they will.

cheerio

[telster]

any press reports yet quoting the usual..

"..thought we were going to die.."

"...crash landed.."

"...narrowly missing a school/hospital/orphanage.."

... i could do with a laugh this morning !

With respect, I think I'm a fairly chilled out passenger, with a good pprune education, but I think I'd have been a bit worried to see a hole appear in the fuselage.

I know most incidents are non-events to those in the industry, but bear in mind that most SLF have little aviation knowledge, and I think "we thought we were going to die" although unjustified would be an understandable reaction.

[green granite]

... i could do with a laugh this morning !

Perhaps you should have been in the cabin on the flight, then you could have had a bellyful of laughs Bruce Wayne.

[LME (GOD)]

The failure was on a chem milled doubler, (Upper lobe, above and behind the 1L door). Aircraft is quarantined pending NTSB investigation. I have some pics but i can't post them??

[green granite]

LME. http://www.pprune.org/spectators-balcony-spotters-corner/203481-image-posting-pprune-guide.html

[LME (GOD)]

http://i56.tinypic.com/30w3scy.jpg

http://i52.tinypic.com/5vouqh.jpg

[kwateow]

I always said the 757 was a sardine can.

[R04stb33f]

Willit Run

Air is compressible, so no hammer effect like hydraulics.Aloha Air flight 293

If I remember correctly, a member of the crew was "sucked" towards a small hole in the fuselage, blocked it, then the 'fluid hammer' effect basically destroyed a good part of the fuselage. Explosive decompression, but aircraft landed safely.

Cheers

Ros

[BRE]

60,000 hours will probably make it one of the oldest jets in legacy service not that NWA have retired their DC-9?

[timothy taylor]

Airframe cycles are the ultimate fatigue and life limiter to a passenger aircraft.

[Huck]

My company has bought several 757's with over 90,000 hours.

Converted them to cargo and put them on the line. Lots of replaced structure, though.

[Spooky 2]

As much a fan as I am of the 757, I recall a Boeing guy telling me years ago that the 757 airframe is no match for the 727.

[MungoP]

Just for the sake of verisimilitude... Talk of 'explosive' decompression is probably inaccurate in this case... 'Rapid' decompression is more likely to be the appropriate term.. If I remember correctly, explosive decompression refers to a total decompression within 1/2 second, this would more likely be the result of a door blowing off, a bomb or a huge structural failure similar to that of the 747 a few years back where passengers were sucked out of the aicraft through a hole you could have driven a volkswagen through... the instant loss of compression often proves fatal to some passengers as lungs and other organs are unable to adapt quickly enough.
Rapid decompression I think is between 1/2 and 1 1/2 seconds... as there were no injuries reported this was the more likely time scale the incident falls into.... or an even slower category...I stand to be corrected.. I'm no expert.

[pattern_is_full]

Aloha Air 243, actually.

The "fluid hammer" effect was suggested as a factor in that accident by an engineer, but not accepted by the NTSB in its final report - which found that widespread fatigue due to a very high number of cycles sufficiently accounted for 1/3 of the cabin skin "unzipping" following the initial failure. http://www.jethag.com/wp-content/uploads/2009/10/243.jpg

But an FA was, indeed, sucked out during the decompression, the sole fatality.

The incident MungoP refers to was United Flight 811: http://www.warman.demon.co.uk/anna/united.jpg - due to an age (but not fatigue) induced cargo-door locking failure.

[Data Guy]

Just another chem milled stress failure says Boeing >>>

"Boeing finite element modeling suggests stress levels are higher in the skin at the edges of chemically milled steps adjacent to non-chemically milled bays due to the difference in stiffness.”

See NTSB's Accident/Incident reports for that earlier Southwest 'skylight' at Link > DCA09FA065 (http://www.ntsb.gov/ntsb/brief.asp?ev_id=20090714X83900&key=1)

Cause > "Fuselage skin failure due to preexisting fatigue at a chemically milled step".

and a good article with more overview at Link >Metal Fatigue Led to Fuselage Rupture|Aviation Safety Journal (http://asj.nolan-law.com/2010/10/metal-fatigue-led-to-fuselage-rupture/)

Looks like the easier exterior inspections may now be a problem. Inside inspections are a lot more work.(ceiling, ducts, insulation).

[SKS777FLYER]

2W2R writes, As it was an AA flight I doubt any American will be brave enough to suggest they could fit through a 1ft x 2ft hole, last AA flight I was on many of them on board were lucky to get through the bloody door!!!
Yes, no doubt Americans are needing cargo doors for boarding these days, but had the unfortunate flight been a Charter of German or English tourists, would be about the same situation. :=

[YRP]

any press reports yet quoting the usual..

"..thought we were going to die.."

"...crash landed.."

"...narrowly missing a school/hospital/orphanage.."

... i could do with a laugh this morning !

Bruce, I don't think a wide-body aircraft like the 757 can narrowly miss anything.

:E

[aterpster]

YRP:

Bruce, I don't think a wide-body aircraft like the 757 can narrowly miss anything.

It's companion ship the 767 is a wide-body; the 757 is not.

[Green Guard]

'fluid hammer' effect basically destroyed

"Hammer effect" exists as much as "Air Pockets"

Also...why this hammer is not active before the hole appeared ?

[threemiles]

I can't see a doubler, just a panel.

[glhcarl]

2 Whites 2 Reds, if you don't think a 1' X 2' opening isn't large enough for a passenger to fit through, how do you explain this from airsafe.com:

3 November 1973; National Airlines DC10; over New Mexico, USA: The aircraft had an uncontained failure of one of the wing mounted engines. A piece of the engine struck the fuselage and broke a passenger window. One of the 116 passengers was sucked out of the aircraft during a rapid decompression. The remains of the passenger were not found.

By the way the DC-10 window is 10" X 16".

[PaperTiger]

It's companion ship the 767 is a wide-bodyTo be really picky, the 767 isn't a wide body either. It's a twin-aisle with just one extra seat per row (Y) vis-a-vis the narrow bodies.

[Data Guy]

Some have asked for some detail to that second fuselage incident being investigated by the NTSB.
First from that American story >

Source; Officials investigate what caused hole in American jet's fuselage | News for Dallas, Texas | Dallas Morning News | Airlines | Dallas Business News (http://www.dallasnews.com/sharedcontent/dws/bus/industries/airlines/stories/1030dnbusjethole.1da1d0136.html)
Quote >
The NTSB is looking at similar damage discovered on a United Airlines plane on Sept. 11, Holloway said. NTSB and Federal Aviation Administration officials said they had not yet conducted broader safety checks of Boeing 757s. End --- see Link above for full text story.
Discussion. In spite of the NTSB’s claim to a September 11 United incident, there is no NTSB record at the NTSB’s Accident/Incident database as of October 29,2010. See NTSB Link > N T S B - Sep 2010 Aviation Accidents (http://www.ntsb.gov/ntsb/AccList.asp?month=9&year=2010) by date

Records search of SDR database for September 11 United fuselage incident Sept 9-12th. Results 51 records. Two records found below for the 10th and Reg 509UA for a dent and 520UA for ‘over a 10 inch crack’. The latter is a severe damage and likely to be the one the NTSB would be looking at. See Below >

Partial texts, See bottom on how to retrieve the full text reports
UALA2010091303389 9/10/10. 757. Reg 509UA. 520UA. JASC/ATA Code 5330. Problem Description; Ext fuselage at BS 418, between STR. 19 and 20l is dented. Major repair accomplished: found dent to be out of limits.
UALA2010091303386 9/10/10. JASC/ATA Code 5330. Problem Description; Fuselage crack on upper crown area. Crack measures 10.75 inches. Located at sta(tion) 426 stringer S4l and above first pax (passenger) window Lt (left)side.

Frivolous Filings. 60 % are spam mail.
In addition and amongst the 51 records were 23 records for code 3350 and 8 records for code 3397. Both codes are for ground replacements of lights and are not required reporting to the FAA but they do serve to ‘pump up’ the numbers and the appearance of compliance. 60 % of the 51 records here (sum of 23 +8) and are typical of the industry - wide practice filings of frivolous filings seen in another one year survey of nine carriers. Quantity does not mean quality.

How to retrieve full text SDR reports.
FAA’s Service Difficulty database and query search;
Link > FAA :: SDR Reporting [Service Difficulty Report Query Page] (http://av-info.faa.gov/sdrx/Query.aspx)
To access SDRs seen here, merely enter the ‘Control Number’ (i.e. UALA2010091303389) into that data field , press “Run Query”.

[blueloo]

To be really picky, the A380 isnt a widebody either...its just a twin aisle jet with 4 extra seats per row....... :} I mean where does it end.....

[kappa]

Here are more initial pictures of the damage immediately after the incident:
http://img5.imagesha...g=imag0188x.jpg (http://img5.imageshack.us/gal.php?g=imag0188x.jpg)

And here are pictures after the repair began indicating and extended area of potential skin failure.
http://img5.imagesha...g=imag0188x.jpg (http://img5.imageshack.us/gal.php?g=imag0188x.jpg)

Edited to add, I’m no aircraft engineer but I read on another forum that this level of the fuselage is an area where the thickness of the aluminum skin is milled down to (to reduce weight?), It was noted that there is no visual evidence of corrosion and no jagged edges. There is speculation that a thickness check may indicate a variance with the specs. If so, I would bet it will precipitate further checks on other Boeing aircraft with aluminum from the same milling batch. I’m sure Boeing has the records.

[grounded27]

Talk of 'explosive' decompression is probably inaccurate in this case... 'Rapid' decompression is more likely to be the appropriate term.. If I remember correctly, explosive decompression refers to a total decompression within 1/2 second

Rapid or explosive, Have you ever dumped a cabin at max Dp out your slow moving outflow valve? I estimate a explosive 12" by 24" (larger than than your out flow valve for type) would give every passenger a bad f-ing hair day real quick!.

None the less lives were in danger at the hands of the crew.

[aterpster]

BRE:

60,000 hours will probably make it one of the oldest jets in legacy service not that NWA have retired their DC-9?

According to the WSJ, the incident aircraft had less then 25,000 hours:

American Jet Suffered Two-Foot Hole, Cabin Decompression - WSJ.com (http://online.wsj.com/article/SB10001424052702304786904575580991048460452.html)

[aterpster]

PaperTiger:

To be really picky, the 767 isn't a wide body either. It's a twin-aisle with just one extra seat per row (Y) vis-a-vis the narrow bodies.

The 757 uses the same "barrels" as the 707.

[NWA SLF]

As an engineer, I am impressed with the radii on the corners of the crack. Heck, I am lucky if I send out a part designed like that and I can get the supplier to match such a nice radius in a corner. I am afraid if I was a passenger in front of business class and this happened, after things settled down I would by itching to get a look at the fracture surfaces.

[glhcarl]

As an engineer, I am impressed with the radii on the corners of the crack. Heck, I am lucky if I send out a part designed like that and I can get the supplier to match such a nice radius in a corner.

I agree, which that leads me to believe that something was done during manufacture of the panel. On the TriStar we had a couple of aft pressure bulkhead failures with similuar shaped failures. The cause turned out to be incorrect trimming of the bonding material. When trimming the excess material with an "exacto" knife the base metal was cut. After 15,000 to 20,000 pressure cycles the failure followed right along the score mark.

[MungoP]

Rapid or explosive, Have you ever dumped a cabin at max Dp out your slow moving outflow valve? I estimate a explosive 12" by 24" (larger than than your out flow valve for type) would give every passenger a bad f-ing hair day real quick!.

Yes I have...
And the difference between 'explosive' decompression and 'rapid' decompression remains significant...'rapid' = bad hair day.... 'explosive' can equal last day worrying about your hair...

[Dairyground]

Is the area where the blowout happened one that is particularly highly stressed in some relatively rare circumstances? The skin wrinkles received by a B767 at Bristol a few weeks ago seem to have been in the same general area, and the thread about that incident refers to two other cases of repairs in similar places, one to the same airframe. These were B767, rather than B757, and I don't know how closely the design teams for these bits of similar products worked. But twice is coincidence, three times is ...:hmm:?

[Machaca]

Example of chemically milled fuselage skin panel:

http://i337.photobucket.com/albums/n385/motidog/chem_milled.jpg


For info on chemical milling of aluminum, check out pages 368-370 of Aluminum and Aluminum Alloys (http://www.google.com/search?tbs=bks%3A1&tbo=1&q=9780871704962&btnG=Search+Books) by J. R. Davis & Associates.

[kappa]

The complete panel above seems to have "radii on the corners" of the individual areas between the location of the structural "membranes(?)".

[glhcarl]

Example of chemically milled fuselage skin panel:

http://i337.photobucket.com/albums/n385/motidog/chem_milled.jpg



Fuselage skin? Looks more like a lower wing panel!

[Mr @ Spotty M]

I would like to add a couple of comments to this thread.
One point is with the reference to the WSJ article, it does not state the aircraft had less than 25000 flight hours, the figures were for the number of flights.
What l can remember with regards to using the same flight barrels as the B707, the skin thickness on the B757 is a lot thinner, hence the special type of rivets used.

[aterpster]

Mr @ Spotty M:

One point is with the reference to the WSJ article, it does not state the aircraft had less than 25000 flight hours, the figures were for the number of flights.

I have to learn to read. :O

Nonetheless, the article went on to say that is not a high-time/cycle airframe.

[Data Guy]

In addition to this newest AD for Southwest - 2010-01-09 Link > The Boeing Company Model 737-300, -400, and -500 (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/17C7B3B0A7BC72D3862576A900530098?OpenDocument&Highlight=2010-01-09)
It is hardly the first. A 2004 AD refers to a Alert Service Bulletin dated Dec 14, 2000.
2004-18-06, 737-200, -200C, -300, -400, and -500 series airplanes, as listed in Boeing Alert Service Bulletin 737-53A1210, Revision 1, dated October 25, 2001; certificated in any category. Effective Date;October 13, 2004. To find and fix fatigue cracking of certain upper and lower skin panels of the fuselage, which could result in sudden fracture and failure of the skin panels and consequent rapid decompression of the airplane. Inspections, repairs, and preventive modifications done before the effective date of this AD per Boeing Alert Service Bulletin 737-53A1210, dated December 14, 2000, are acceptable for compliance with the corresponding actions required by this AD.
See Link for full text > Boeing Model 737-200, -200C, -300, - 400, and -500 (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/F3FC2C49B4C790F586256F090052264B?OpenDocument&Highlight=ad%202004-18-06)

Then in 2008 >

2008-12-04. 737-600, -700, -700C, - 800, and -900 Series Airplanes SUMMARY: We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. This AD requires various repetitive inspections to detect cracks along the chemically milled steps of the fuselage skin or missing or loose fasteners in the area of the preventative modification or repairs, replacement of the time-limited repair with the permanent repair if applicable, and applicable corrective actions if necessary, which would end certain repetitive inspections. This AD results from a fatigue test that revealed numerous cracks in the upper skin panel at the chemically milled step above the lap joint. We are issuing this AD to detect and correct such fatigue-related cracks, which could result in the crack tips continuing to turn and grow to the point where the skin bay flaps open, causing decompression of the airplane. This AD is effective July 16, 2008.
This AD applies to Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category; as identified in Boeing Special Attention Service Bulletin 737-53-1232, dated April 2, 2007.
See Link for full text Boeing Model 737-600, -700, -700C, - 800, and -900 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/3DB5E1F9035BC25E8625746500523451?OpenDocument)

[llondel]

Green Guard:
"Hammer effect" exists as much as "Air Pockets"

Also...why this hammer is not active before the hole appeared ?

The hammer effect is where a hole develops, the entire air mass in the fuselage starts moving towards the hole and then suddenly the hole is blocked. You can hear it in water pipes when a valve suddenly shuts, but it can happen with a compressible medium such as air as well. There will be a pressure spike which, if the container holds, will dissipate safely. If it exceeds the material strength of the container then it will rupture.

The alternative Aloha 243 incident was that this happened - the outflow started, the flight attendant got sucked into the hole and got stuck, then the excess pressure ripped the rest of the fuselage off, fracturing at weak points all around. I suspect the NTSB version would have it that everything started and propagated from one place.

So, no hole, no hammer. (

[GlennAB1]

I don't see how the flight attendant could block the initial hole (causing a fluid hammer effect) with all the fuselage structure (frames, ribs and stringers) and cabin decorative panels in the way.

[contractor25]

airframe fatigue depends entirely on flightcycles, not on airframe hours. I have worked on Fokker 100 with 49000hours/41000cycles but also on B747 with 101000 hours/12000cycles. in calander age the boeing was newer, but in airframe life the fokker is 4 times older.

For years there have been structural mods on lapjoints on Boeing, especially the 737 series (good little earner), most of them come to light during ageing aircraft inspections.
But still there are people in the trade who think it's not a problem to use stanley blades and the like on a pressurised hull.....

[GlennAB1]

Although scribe line damage is a problem, it isn't related to AA 757 flight 1640; MIA-BOS on Oct. 26th