No problem Sprocky, that was the only one which I could think of. I'll let others more knowledgeable than I answer your questions. :)

There is a lap joint at that location, so either it was corrosion, a substandard repair or a scrape in the surface of the aluminum which cracked from pressurization cycles. Missing rivets thru the aluminum skin to the underlying stringer is also another possibility.

Hope they find the root cause soon and get all of those craft flying again.

Ripping Yarns
 

How very inconvenient for this to happen to a -300, just before the Supreme Court case involving the firing of the 737NG assembly line inspectors who blew the whistle on the defective chord sections and "bear-straps" from a Boeing sub-contractor?!

What happens when the 1st NG made mid 90s to mid 2000s suffers a sardine can experience?

Put A H F Ducommun in your search engines, ignore the company puffs and look for the nasty bits if anyone fancies doing some research on this topic.

Then buy our ticket and pray. :confused:

CGs have a regular NDT inspection on this structure I believe. HFEC as well. Most NDT inspectors I know aren't into the sharp pen business or bowing to pressure from management. Of course I cannot speak for the inspectors that last checked the airframe in question.. Lap Joint?? More possibly a pocket IMHO, but what do I know?:E

I would like to hang anybody I see scraping lap joints with metallic or non approved scrappers.. they should be excuted..:E

Two observations on a brighter note:

1. This and previous happenings with happy outcomes do speak volumes for the damage-tolerance of the 737 fuselage design.

2. The flying public, seeing this on the TV news and hearing the testimony of witnesses, will be motivated to heed the safety advice and keep their seatbelts fastened at all times they are in their seats.

> Ducommun
Good pointer, thank you. Among the first page of results:
Washington Post Article | Political & Social Justice Project | Schuster Institute | Brandeis University

Six Prior SW Depressurization Events
 

Mar 2009 thru Nov 2010 Service Difficulty Reports

For full text reports, see FAA’s SDR database at this Link > FAA :: SDR Reporting [Service Difficulty Report Query Page] Enter SDR # into the “Operator Control #” field and run query.

Service Difficulty Report – Control Numbers >

SWAA107101 11/14/2010 Reg 773SA No data.
SWAA106876 10/28/2010. Reg 902WN At Fl 380
SWAA094502 07/13/2009. Reg 387SW At FL330
SWAA093897 06/15/2009. Reg 522SW At FL 230
SWAA092547 04/18/2009. Reg 654SW At Fl 290
SWAA091992 03/29/2009. Reg 358SW At Fl 260.

Sprocky_ger

That is correct. March 2009 $7.5 million settlement was for alleged maintenance violations which occurred in 2008. That figure was reached after months of negotiations - the FAA had originally demanded much more.

I was inspecting an A320 fuselage during a heavy mtce check a few year ago and I found a row of missing rivets thru the skin and underlying stringer. So human factors play a major part with regards to mistakes.

more rivets ...the only answer!

I flew the Aloha 737 that became a convertible about 100 hours before our airline gave it to Aloha. We normally cruised at 35,000 ft. Aloha was only about 20,000 ft when the top blew off. We always train for emergency descents but have never had to do a real one. They did just fine at SWA getting it down. Good bunch of pilots there.

Techgeek may be on to something. Many of the recent commentators have apparently not read the link to the AD that he posted. Here it is
in summary form without the compliance time limits:

Quote:

---

AD 2010-25-06

This AD is effective February 1, 2011.

BS 616 and BS 639 inspection/lower frame and stub beam
15 work hours

This AD applies to The Boeing Company Model 737-200, -300, -400, and -500 series airplanes ...
The Federal Aviation Administration is issuing this AD to detect and correct fatigue cracking of certain fuselage frames and stub beams and possible severed frames, which could result in reduced structural integrity of the frames. This reduced structural integrity can increase loading in the fuselage skin, which will accelerate skin crack growth and could result in rapid decompression of the fuselage.

---

It appears that the observed failure is in just that area. Severed frames would cause a longitudinal crack to develop.

that seems right

Two Questions:-
(1) Did the hole in the roof cause the decompression?????:confused:
(2) Do 737's have a pull top tab on the inside of the fuselage???:ok:

AD-2010-25-06 and SWA 812
 

Looking at the picture someone posted and a 737-300 Station Diagram it looks like the skin panel that opened up begins around STA 663.75 and continues past STA 706 and ending before STA 727. So, it is close but not exactly correlated with the locations cited in AD-2010-25-06. I suppose the NTSB will have something to say if it turns out this AD was involved.

Regarding post # 8

<<< 1. did something like this happen outside US also in the past? >>>

It is difficult to say exactly what "this" is until we know more about what caused the event in question. (For instance, was there any prior damage near the site of the failure that was undetected or improperly repaired?)

With that caveat, my understanding is there have been some incidents outside the US involving explosive decompression attributed to undetected (or unrepaired) corrosion or cracking.

A Far Eastern Air Transport (Taiwan) 737 crashed on August 22, 1981, following an explosive decompression event and in-flight breakup. Probable cause was found to be extensive corrosion damage in the lower fuselage structures, probably exacerbated by what was considered to be a large number of flight cycles.

Two other events outside the US involved 747s: China Airlines 611 and JAL 123. My understanding is that in each instance, the plane had sustained a tail strike some years before (22 years for China 611, and approximately 10 years for JAL 123).

In both cases, repairs were not properly performed. Over the years (and thousands of cycles), small fatigue cracks developed, grew, and connected with other cracks. Inspections either were not performed or failed to detect/correct the problem. Both planes eventually sustained an in-flight explosive decompression culminating in catastrophic structural failure, at a total cost of over 700 lives.

The real pilots here undoubtedly know of other such incidents. (I posted this only because it did not appear that anyone had directly addressed the question you raised.)

Ditto, the eldest a/c in the FR fleet EI-DAD! (no pun honestly) is about 4 years old from recollection.
The average fleet age is circ 2.5 years (airframe 300 came in Feb11!)
So with one of the youngest and most standardised fleets in the business, coupled with as strong a maintenance regime as any of the dinosaur airlines they are inherently safe.


If they are anywhere near as "pikey" as a lot of contributors try to imply, how come the only "decent" hiccup they have had was the multiple bridstrike in Ciampino? And whats that? oh yeah they did as good a job as the boys and girls on the BA 777 into LHR

Sorry ill take off my reality spec's now and look at the world in the rose tinted Legacy Is Best -The Rest Is Cowboys and Dangerous:ugh::}

Jeez some days if i had a subscription I'd cancel it
Unfortunatly im addicted to trashy comments as much as i am at throwing my shoes and houshold goods at the TV when ever Jeremy Kyle comes on

:}:}:}

The past history of SDRs as SWA is very concerning as it smacks of Aloha but on a far bigger scale.:\

Its another sign that airlines need to invest in SMS introduction to manage this sort of problem better.;)

I for one had not realised that they had not been investing in new aircraft like Ryanair.
:ok: to M O'L.

I wonder if the AD will now be revised.:confused:

Techgeek,

Whats all this doing research before posting?

Don't you realise this is a 'Rumour Network'?

You have confused the whole thread by introducing FACTS!!!

Well done that man :ok:

Shell Management:

They spent a huge amount of money retrofitting all their aircraft to be able to do RNP AR. Then, they are pushing complex, multi-path RNP AR IAPs at all their airports to hopefully save a bit of fuel here and there.

This was not the original objective of RNP AR, but SWA has forced the issue at the highest levels of the FAA. They are a very tough player.

Seems there might have been some warning?..

Southwest to ground 81 planes after hole prompts emergency landing - CNN.com

aterpster - not sure why you think that investment in aging aircraft is a postive one.

I wonder if that attitude has had a negative effect on safety.

Shell Management:

Did I state or imply that? The only investment aging aircraft should get is increased maintenance, especially heavy maintenance

lot of older planes out there...our B52's are in their 50's...but they constantly get rebuilt

sevenstrokeroll:

The Air Force doesn't try to cut costs in the B52 program. Also, I suspect the cycles per flight hours is very low.

Severed Frame
 

Regarding the AD, what exactly is a severed frame? TIA

The main issue with cycles is repeated pressurization/depressurization of the airplane. The B52 is not pressurized over the length of the fuselage.

Better understanding
 

Have 2 questions for U guys out there:

a) Where do you find the cycle and hours data for a given airframe ? If you feel uncomfortable posting the answer, a private message is fine.:ok:

b) Given that the low cost airlines will automatically end up with high cycles and relatively high hours on short haul aircraft how do the different airframe retention concepts of SW v. the 2 major european players affect safety and incident statistics ? (run forever to get as big a bang for your investment buck v. replace while still in prime of life and optimise on second hand value at times when new airframes are at a premium due to short supply).:ugh:

Old Fleets
 

Ryanair still getting new airframes. 3 new 737 on the flightline at Seattle when I passed an hour ago!!

AP reports:

I may be missing the crux of your question so feel free to accept other's responses.

The airframe hours and cycles are part of the required record keeping and of course one of the first things the NTSB will publized after they are vetted.

Fleet management has many considerations, commonality, market fit, repair and maintenance, etc. regardless of new or old safety management is a task shared by the operator, the manufacturer and the regulator. So in my mind there is no intent to see how far you can run an airplane to see if it will break catstrophicaly. Anywhere along the line, human error and/or ignorance (surprise factor) is present. No way would I predict anything else. I await some more specific investigative facts before delving more deeply into anything more.

cessnapete:

Correlation based on random observations is not useful.

737 deliveries since 1999:737 orders in last year:

drifting
 

I found discussion on another forum in relation to this accident that allegedly Southwest ask their pilots to do firm landings (hard landings?). I am not going to repeat the whole line of argument how this claim might relate to this accident but I would like to verify if there is any truth in it in case there are some SWA pilots around here.

You are neglecting the "options" that RYR turned into orders, no point in placing any more orders when you have the fleet size you want and new players offerring more attractive price/equipment propositions

deSitter
Aluminum fuselage construction involves a series of hoop like frames that give shape to the fuselage. If fatigue cracking initiates on the inner or outer face of the hoop, it can progress until it cracks through all portions of the hoop, finally completely severing the hoop's continuity. At that point, all pressurization loads are being entirely handled by the skin in the area of the severed hoop (frame).
One can envision the entire fuselage tube bending down aft of the wing during turbulence and during firm landings. The tube bends by flattening its outside radius in the area of the bend. The frames resist this flattening which is how they become exposed to fatigue.

Note: Those who design aircraft structure are welcome to improve on this description--Not my area of specialty.

I don't fly for southwest...but landings are like sandpaper...use the rougher grades in certain circumstances, the smoother grades in other situations.

plus, it is a bit of luck getting a smooth landing.

actually, firm landings in some circumstances are the safest ones to do.

Machaca, Your post was of no use to anyone.
However to add to the pointless posts, with regards to SWA & RYR.
Fact, RYR only have 737NG aircraft and are retiring the oldest airframes, SWA still have B737 classics.
One other pointless fact, an MRO that has FAA approval, does not need to have Mechanics or Inspectors with an FAA licence, thank God.
If you have seen some of the FAA registered aircraft that have gone through overseas MRO's, then you would all change your opinion on how good FAA operators are.

In the UK, look at BMI Baby...

I cant remember if theyve got rid of all their 300's but I'm sure there are still some around and even their 500 series 737's are getting old.
Some used to be ex BMI and I believe they had an ex BA one too.

Some are over 10 years old. Most of them 15 years or more.

I like BMIBaby but dont you think it is time they renewed some of their aircraft.

Try NAS...:E