Southwest Flight 812

[BoeingBoy]

The aircraft had previous cracks repaired, but I haven't seen where it was the actual joint that was repaired.

From what I've seen the previous cracks were in frames/stringers, which the FAA has an existing AD for the 737's except NG models. A NTSB official that used to be a pilot for US has been quoted as saying that normal inspection procedures wouldn't discover the very small cracks found on the lap joint side the the panel that came loose. Apparently what nobody knows yet is how fast undetectable cracks can turn into big enough cracks to cause a skin panel to peel back.

Jim

 

[tech2101]

From what I've seen the previous cracks were in frames/stringers, which the FAA has an existing AD for the 737's except NG models. A NTSB official that used to be a pilot for US has been quoted as saying that normal inspection procedures wouldn't discover the very small cracks found on the lap joint side the the panel that came loose. Apparently what nobody knows yet is how fast undetectable cracks can turn into big enough cracks to cause a skin panel to peel back.

Jim

As you know Jim, and most here may now, that every aircraft has many cracks in it's strcture repaired over the life of the airframe. I repaired many of those DC-9's that NWA/DAL is still flying. When the media comes out and says "this aircraft has had cracks repaired before" means little to nothing.

 

[UPNAWAY]

^ Good point, the media was all excited about the aircraft having over a "Hundred Repairs".


I had heard the tears trips failed too? Has that been confirmed? If so that should be a real concearn for Boeing.

 

[chris perry]

Was this aircraft one of the ones farmed out to AEROMAN? I know they do 737-300 overhaul.

 

[WorldTraveler]

as much as everyone wants to find a foreign MRO as the cause of the problems, WN said and the FAA has indicated that at least preliminarily there is no indication that WN failed to do anything it was supposed to do... in other words, indications are that the failure likely would not have been found with existing inspection techniques, regardless of who did them.

The fact that Boeing sent out a special advisory accompanied by similar actions by the FAA indicates that inspection techniques and frequencies will change.

I am sure there will be plenty said if WN or a contractor is found to be at fault but that does not appear to be the case.

 

[Bob Owens]

news reports says that FAA records show the plane in Friday's incident was repaired about a year ago for a whole in the fuselage.
It certainly appears that there is a recurring problem here...
.
and it does put pressure on Boeing to fix the problem completely or risk order defections... the Boeing narrowbody tube has been flying for decades... they should be able to get it right by this point.

What is a "whole in the fuselage"?

I am sure there will be plenty said if WN or a contractor is found to be at fault but that does not appear to be the case.

Does not appear to be the case? How do you know that with the little info thats been put out? While they havent pointed any fingers yet they certainly havent absolved anybody and I believe its the NTSBs call anyway. From the photos it appears to be a failure at a lap joint. The failure on the AA757 was a failure of the panel where material was etched out to make the plane lighter, they are very different failures. Lap joints are subject to corrosion and cracking because its where three surfaces meet and was the cause for the failures at Aloha and UAL and should be found during heavy checks,when the paint is stripped. The AA failure, which lead to a much smaller hole and slower decompression rate for those in the cabin, (partial as described by someone else here) is probably more troubling to Boeing because it probably cant be pinned on maintenance, its pretty clearly a manufacturing defect whereas the lapjoint failure is probably due to corrosion and or unaddressed cracks between rivets and can be considered a maintenance failure because corrosion and cracks at these locations is pretty common and should be looked at during heavy checks.

We probably wont hear the exact cause for months.

Well one thing is that if this is due to outsourced maintenance it could put AA in a world of hurt. If SWA decides they need to do the work in house they can easliy draw as many mechanics as they need, with a lot of expertise, from AA. AFW and DFW are within commuting distance to Love Field and that Dalfort facility looks pretty big.

Its about time SWA grew up and started acting like a full grown airline instead of an upstart and do their OH inhouse.

 

[chris perry]

What is a "whole in the fuselage"?



Does not appear to be the case? How do you know that with the little info thats been put out? While they havent pointed any fingers yet they certainly havent absolved anybody and I believe its the NTSBs call anyway. From the photos it appears to be a failure at a lap joint. The failure on the AA757 was a failure of the panel where material was etched out to make the plane lighter, they are very different failures. Lap joints are subject to corrosion and cracking because its where three surfaces meet and was the cause for the failures at Aloha and UAL and should be found during heavy checks,when the paint is stripped. The AA failure, which lead to a much smaller hole and slower decompression rate for those in the cabin, (partial as described by someone else here) is probably more troubling to Boeing because it probably cant be pinned on maintenance, its pretty clearly a manufacturing defect whereas the lapjoint failure is probably due to corrosion and or unaddressed cracks between rivets and can be considered a maintenance failure because corrosion and cracks at these locations is pretty common and should be looked at during heavy checks.

We probably wont hear the exact cause for months.

Well one thing is that if this is due to outsourced maintenance it could put AA in a world of hurt. If SWA decides they need to do the work in house they can easliy draw as many mechanics as they need, with a lot of expertise, from AA. AFW and DFW are within commuting distance to Love Field and that Dalfort facility looks pretty big.

Its about time SWA grew up and started acting like a full grown airline instead of an upstart and do their OH inhouse.

 

[swamt]

The WSJ on Tues. has Boeing admitting to having misshaps leading to the cause of the incident occurring Fri. Apr. 1st It looks like Boeing will be taking the blame.

FIX THE WEB SIGHT. IT KEEPS WANTING TO CONTINUOUSLY RELOAD...

 

[WorldTraveler]

The WSJ on Tues. has Boeing admitting to having misshaps leading to the cause of the incident occurring Fri. Apr. 1st It looks like Boeing will be taking the blame.

Thank you.
There are clear indications that this event was the result of Boeing not expecting and not designing for this type of failure to have occurred at this point in the life of the fuselage…. You are correct that Boeing has admitted that there is a clear need to identify and correct these types of problems earlier than they admitted.
That being true, then there are no key issues in this case that point a finger at WN for not doing what it was supposed to do – either on its own or by its contractors. Even if those turn out to the case, it doesn’t change the role Boeing had…which means this problem is not restricted to any carrier based on whether they outsource their overhauls or not.

What is a "whole in the fuselage"?'

The whole means the entire thing…being able to see the picture from a complete perspective and not just carved up into little parts (ie immediately jumping on outsourcing or WN when there are no indications those are the root problems)

'Does not appear to be the case? How do you know that with the little info thats been put out? While they havent pointed any fingers yet they certainly havent absolved anybody and I believe its the NTSBs call anyway. From the photos it appears to be a failure at a lap joint. The failure on the AA757 was a failure of the panel where material was etched out to make the plane lighter, they are very different failures. Lap joints are subject to corrosion and cracking because its where three surfaces meet and was the cause for the failures at Aloha and UAL and should be found during heavy checks,when the paint is stripped. The AA failure, which lead to a much smaller hole and slower decompression rate for those in the cabin, (partial as described by someone else here) is probably more troubling to Boeing because it probably cant be pinned on maintenance, its pretty clearly a manufacturing defect whereas the lapjoint failure is probably due to corrosion and or unaddressed cracks between rivets and can be considered a maintenance failure because corrosion and cracks at these locations is pretty common and should be looked at during heavy checks.'

Of course we would expect you to defend AA’s maintenance practices done in-house over a contractors but how about, Bob, you take a look at the number and value of FAA fines levied or proposed against AA over the past 2 years compared to other carriers and let us know what you find?

'The AA failure, which lead to a much smaller hole and slower decompression rate for those in the cabin'

Btw, the past tense of the verb “lead” is “led” 

‘Its about time SWA grew up and started acting like a full grown airline instead of an upstart and do their OH inhouse.’

Bob, if we were talking about any other airline, your argument might hold some validity… but we are talking about Southwest Airlines which has been the most consistently profitable airline in US and perhaps global aviation history.
How about you admit that it is time for unions at AA to recognize that times have changed and with it unions must change as well.
It is no surprise that WN has some of the best relationships with its employees of any unionized company, esp. among airlines. While you and others want to continue to argue that it is management’s job to fix the problems at AA, other airlines including WN continue to look for opportunities to grow in AA’s key markets.
How about considering that perhaps WN’s formula is the right formula for the industry and you as a labor leader need to figure out how to work within that formula instead of continuing to fight for a model which only the highest cost and least profitable airline in the US continues to cling to?

'Well one thing is that if this is due to outsourced maintenance it could put AA in a world of hurt. If SWA decides they need to do the work in house they can easliy draw as many mechanics as they need, with a lot of expertise, from AA. AFW and DFW are within commuting distance to Love Field and that Dalfort facility looks pretty big.'

It is far more likely (and still not terribly likely) that WN will be coming across town to pick up 738s which AA has to jettison as part of its liquidation.

 

[eolesen]

Bob, I get where you're going, but seriously doubt anyone would want to be bidding on Dalfort. One can only imagine how much ground contamination issues it has from being in service for 50+ years...

They'd be much better off building a greenfield location where they could put the right safeguards in place for runoff, etc. as AA did when they built AFW and UA did when they build IMC.

Also not convinced Dallas is the right place in general... In North Texas, how long you've lived there is not measured in years, but by how many roofs and cars they've had to replace due to hail damage. Might make more sense to consider a place like PHX or LAS, where you've got less severe damaging weather and abandoned military bases being turned into industrial parks with runways...

 

[chris perry]

Boeing knew full well what the limtations on the airframe are. I just happened to work at a test facility doing that Kind of testing on airframes. Every square inch of that airframe has been tested to failure.They are put through cycle testing to the life of the airframe.If the airframe had no problems it wouldnt have been changed in design on later models. So the notion that this is a new problem is well suspect. It just surfaced sooner than expected....every new model or block of aircraft is fitted with strain guages and vigoriously bent shook,frozen,heated etc....

 

[WorldTraveler]

Boeing knew full well what the limtations on the airframe are. I just happened to work at a test facility doing that Kind of testing on airframes. Every square inch of that airframe has been tested to failure.They are put through cycle testing to the life of the airframe.If the airframe had no problems it wouldnt have been changed in design on later models. So the notion that this is a new problem is well suspect. It just surfaced sooner than expected....every new model or block of aircraft is fitted with strain guages and vigoriously bent shook,frozen,heated etc....

Chris,
if you are involved in engineering, then you know that designing for failure is a statistical exercise... not every component of any design fails at the same point. Boeing could well have known exactly the point at which a component would be LIKELY to fail but the statistics that say when a failure is likely to occur are an estimate because you can't test to the level to generate 100% failure every time.

 

[WorldTraveler]

Boeing knew full well what the limtations on the airframe are. I just happened to work at a test facility doing that Kind of testing on airframes. Every square inch of that airframe has been tested to failure.They are put through cycle testing to the life of the airframe.If the airframe had no problems it wouldnt have been changed in design on later models. So the notion that this is a new problem is well suspect. It just surfaced sooner than expected....every new model or block of aircraft is fitted with strain guages and vigoriously bent shook,frozen,heated etc....

Chris,
if you are involved in engineering, then you know that designing for failure is a statistical exercise... not every component of any design fails at the same point. Boeing could well have known exactly the point at which a component would be LIKELY to fail but the statistics that say when a failure is likely to occur are an estimate because you can't test to the level to generate 100% failure every time.

 

[lpbrian]

Chris,
if you are involved in engineering, then you know that designing for failure is a statistical exercise... not every component of any design fails at the same point. Boeing could well have known exactly the point at which a component would be LIKELY to fail but the statistics that say when a failure is likely to occur are an estimate because you can't test to the level to generate 100% failure every time.

Perhaps some SW amt may speak english??

 

[wasone]

Perhaps some SW amt may speak english??

Word on the steet is that the next aircraft SW buys will be Airbus.