Southwest, 737s, and Holes: What Happened and What Now?

I’m sure a lot of you have been wondering why I haven’t written about the Southwest 737 that had a big hole open up inflight last week. It was big news for sure, but I just didn’t know enough beyond the basic information to make a post worthwhile. Southwest is still not saying much at all, but I was able to piece some things together from other sources to get a better idea of what’s actually going on. It all starts with a lap joint.

Lap Joint Problems on 737s

What Happened
Last week, a Southwest 737-300 airplane was flying from Phoenix to Sacramento when a hole opened up in the roof. The airplane lost pressurization (of course) but the pilots were able to land the airplane in Yuma and everyone was fine. You may have heard people talk about how the airplane plunged after the hole appeared, but that was on purpose.

When an airplane loses pressurization at altitude, you can’t breathe. And that’s a problem. There are oxygen masks but those don’t have an endless supply of oxygen in them. So anytime this happens, the pilots are trained to go into a steep descent until they get to around the 10,000 foot mark where the air is breathable. It may seem like you’re plunging, but it’s all part of the plan.

Once on the ground, it was easy to see that this was no small hole. It happened in the crown of the airplane along a lap joint. That’s a horizontal line where two pieces of the skin come together and are fastened to each other. As you can imagine, this area is cause for concern regarding fatigue because joints are the weakest points in a structure.

Tear Straps
The part that’s really concerning here isn’t the tear itself so much as it is the size of the tear. See, on all these airplanes, they install what are called tear straps. The aircraft of particular concern are the 737-300, -400, and -500s, collectively called 737 Classics. Next Generation (or “NG”) airplanes make up the bulk of the 737s you’re likely to fly, including all of the ones that American and Delta operate. Those had a different design and are newer so they aren’t impacted by this. I’m sure, however, that the FAA and Boeing will be watching this closely.

But back to the Classic airplanes. On the older models, these tear straps were placed every 10 inches horizontally along that lap joint. In 1993, a change was made that resulted in the straps being needed only every 20 inches. These tear straps are meant to stop any crack from spreading further. In other words, even if a hole opened up, it should never go further than 10 or 20 inches depending upon the airplane because the tear strap will stop it.

As you may have seen, this went for feet, not inches, and that means that the tear straps were breached. That is not good. So, Boeing, the FAA, and the airlines are diving in to try to figure out what exactly happened here. But for now, they are simply mandating inspections for cracks so that this never even becomes an issue. Why weren’t these being inspected before? That’s a different story.

Shouldn’t These Have Been Inspected?
For the older 737 Classic models that were built before 1993, there were directives issued that required inspections (using technology, not visual) for aircraft with more than 45,000 cycles. That was eventually lowered to only 35,000 cycles. One cycle is one takeoff and landing. This metric is used because that’s a good measure of how much stress is put on the airframe going through the pressurization process.

At US Airways media day yesterday, that airline confirmed that all of its 737s fall into this category, and they’ve been doing the inspections since the FAA mandated them early last decade. More than half of Southwest’s 737-300s fall into this category, so presumably the airline has been conducting these checks as required. But it didn’t use this as a standard 737-300 maintenance procedure for the full fleet. On those airplanes built after the 1993 manufacturing change, none of these non-visual inspections were done, because they didn’t have to be done.

With hindsight, that’s too bad, because had Southwest inspected all of its 737-300s, it would have found the cracks. The airplane that opened up a hole had more than 39,000 cycles. But the newer manufacturing process wasn’t expected to have problems this early on in the life of the airplane. In fact, Boeing thought that 60,000 cycles would have been a good conservative number for an inspection. Now, the FAA has mandated checks on these newer airplanes starting at 30,000 cycles.

So as you can see, there’s a lot up in the air. Nobody knows why cracks are showing up on these airplanes so early in life, but stepped up inspections will make sure that they are safe to fly regardless. Now the investigation can focus on why this is happening.

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51 Comments on "Southwest, 737s, and Holes: What Happened and What Now?"

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Nick Barnard
Member

This is definitely not a good thing, but looking at this from the positive side, there was a failure, and the plane still landed safely.

Although, I wonder if this’ll push any orders toward Airbus? Its small, but Boeing jets of this vintage have had a rash of these incidents lately…

JJG
Guest

I wonder if this will speed up SWA’a 700NG orders going forward? Just from PR standpoint, I think they might like to get past the 300 era sooner rather than later.

astra
Guest

I’m just wondering why the inspection threshold wasn’t lowered the last time WN had a depressurization incident on a 737-300 in July of 2009.

Dan
Guest

So much for “If it ain’t Boeing, I ain’t going.”

David SF eastbay
Member
It’s like everything else in life, things just aren’t made like they used to be. And nothing they test in a lab will ever give the same results as normal everyday use of a product to know if something will last a certain time or not. Kind of funny but this weekend the Liberty Foundation will be at my local airport and you can take rides in a B-17 fortress or P-40 war plane (if you have a fat wallet to pay the price). I wonder how many people will feel completely safe in a 60 year old plane compared… Read more »
james
Guest

Last fall an Al Jazeera investigative show did a full program on two Boeing whisleblowers, who around 99-01 brought to attention the quality and workmanship of the supplier that produced the “bear straps” parts for the 734NG. Allegedly many of the parts didn’t fit to exact specifications, but not rejected as on-conforming, and as one interviewed said flat out made the plane non-airworthy.

I thought it was very well done, not sensationalistic, and both sides well represented.

http://english.aljazeera.net/programmes/peopleandpower/2010/12/20101214104637901849.html

Derek
Guest

Thanks for sharing, all I can say is wow.

Armond
Guest

There you go.

Bottomline = money.

Of course Boeing knew about it. It had to…

Nick Barnard
Member

If Boeing knew of problems and they didn’t address them or share them with the appropriate agencies, they’d end up being criminally negligible, something that they’re not stupid enough to do.

Air travel is the safest its been. In the past accidents like this resulted in deaths, instead, we have some scared passengers and a plane that is out of commission. Not a bad deal..

Armond
Guest

Are you serious? Have you watched the video above? Of course Boeing knew about the problem….how obvious does it have to be????

Sorry man…I totally disagree with you. Safety in flight is a smokescreen. The margin of safety is very very small in reality.

The US government has protected many companies in the past….Halliburton, etc…protecting Boeing is paramount…screw people.

Nick Barnard
Member

I haven’t watched the video, but I read the article. Yes there are problems with parts. I never expect anything to be perfect.

The fact is the number of fatalities per passenger on airliners are the lowest of any form of travel. Its likely more dangerous to walk across the street, and it definitely is more dangerous to go driving than to fly in an airliner.

Armond
Guest
That’s a ridiculous thing to say “there are problems with parts.”….not with structural components you don’t….NEVER. Not on aircraft. These critical components were fitted on these aircraft with full knowledge and understanding of parties involved and the government completely was in bed with Boeing and looked the other way. It’s as simple as that. The number of fatalities in flying may be low but per accident, the fatalities are extremely high. You will not survive most likely. All the more reason to bring Boeing to justice about this….the margin of error is too small and the false feeling of security… Read more »
Nick Barnard
Member
Agreed, that the number a fatalities per accident are higher with aircraft, thus why emphasis is placed on not having any accidents. Simply we don’t have the full story on this. Lots of really smart people spend time engineering airplanes. I know a 789 engineer who has spent four years working to develop a 30 page document of the fatigue related to a single system on the plane. They’re very through in their investigation and engineering. I’m not an airplane engineer, but I realize that people who are experts in their field deal with a great deal of complexity that… Read more »
Armond
Guest

I’m in that business …I’m an aerospace engineer. So walk in those shoes every single day.

Nick Barnard
Member

Let me know what plane you worked on designing, because I’ll make sure to fly on it.

Armond
Guest

I don’t work on aircraft…I work on spacecraft, satellites, and space stations.

ken
Guest

I am rather disappointed in article that you sent out. The way I interpreted it is Southwest did not do a good job of inspection. Please see the article below and the one at the following link. I think you owe your readers more than just speculation or opinion. You did work for an airline at one time.

http://www.msnbc.msn.com/id/42437823/ns/travel-news/
Boeing didn’t expect 737 cracks so soon

Reader wonders why we’re not reporting much on Southwest Airlines’ maintenance problems
By Terry Maxon/Reporter
http://aviationblog.dallasnews.com/archives/2011/04/reader-wonders-why-were-not-re.html

Robert
Guest

Has this ever been a problem with DC-9, MD-80, 88, 90 series planes? They do a lot of cycles also but have never heard of that happening to them.

Armond
Guest
Don’t count on the FAA to do anything…even with the NTSB’s recommendations. The FAA runs on the philosophy of “Tombstone Technology.” Things are done after the fact and then it’s too late. But airlines needn’t worry. The bean counters at airlines have already figured out the hit airlines will take if an accident occurs. Airlines are OK with a certain amount of accidents/deaths for an airline’s operation. It’s all calculated in the cost of operation. Insurance takes care of the rest. They penny pinch until the last moment or beyond and understand FULLY the risks associated with such methods of… Read more »
Nick Barnard
Member

The FAA and the NTSB have disagreed for years, that isn’t news.

Airlines don’t like accidents. Accidents can and have brought down airlines. PanAm would likely still be flying if it wasn’t for flight 103.

Armond, which airline would you prefer to be flying? And if you really wanted to I’m sure you could get to Hawaii by not flying on a US carrier. If you’re in the US you could go via Vancouver, BC, Canada or even via London England without flying a US carrier.

Armond
Guest
Nicholas: Airlines don’t like accidents…but there operational methods take these incidences into account monetarily. They are taking a gamble in terms of surviving the fallout of “bad press” but it’s clear they are willing to do it. There a many FAA/NTSB directives to make changes on aircraft (many of them “voluntary”) of which airlines do not spend the money to do…clearly stated by the former FAA inspector at 41-42 minutes of the video above. I’m actually flying from Los Angeles…too late…we booked it!!!! Shit! It’s very very clear that the government, the FAA, and the airlines are, for the most… Read more »
Nick Barnard
Member

Armond,
A question for you, when booking your flight from LA to Hawaii, did you pick the cheapest flight? If so you’re contributing to exactly what you are complaining about.

Armond
Guest

Nicholas….

I believe you should really think about what you’re saying…do I seem like a person who would pick the cheapest flight given how little faith I have these firms?????

Unless absolutely necessary, I ALWAYS choose a direct flight…which are always the most expensive. Our trip to Hawaii is no exception. We booked a direct flight non-stop and paid up the yazoo for it.

Nick Barnard
Member

I choose my words carefully, thank you very much.

But of the direct flights, did you choose the cheapest ticket price? Why not pay more? That would allow the airline to spend more on maintenance. (and yes, their other costs and profits.)

If you still chose the cheapest ticket price you’re contributing to the cost pressures in this industry, and have little right to state what you have stated.

You still haven’t answered my question, given any airline in the world, which airline would you prefer to fly?

Armond
Guest
What on earth are you talking about? No I do think you really should choose your words more carefully… I booked the deal as a package and the ticket cost was included in the deal but the deal cost ALOT more for direct flights. Whether it was the cheapest or not I can’t say but was at least 50% more than multiple stops. Stop being a strawman…you know damned well nonstop flights are much more expensive….telling me that I chose the “cheapest” nonstop flight is stupid frankly. Sorry. And to answer your question…Singapore, Emirates, and Air Tahiti Nui are the… Read more »
Nick Barnard
Member
No Armond, I’m making the point that even people who state that they care about safety won’t pay for it. If you were given the option to pay two times your air fare price, to fly on a plane that’s maintenance, construction, and operational standards were certified by an independent authority (say Underwriters Laboratories or a similar outfit) would you? Probably not, I’ll admit that I wouldn’t and most passengers wouldn’t. Cost pressures are the rule in this industry. Thats just the way it is. I took a brief peek at Singapore Airlines, Emirates, and Air Tahiti Nui’s accident and… Read more »
Armond
Guest
Nicholas, Using me as an example is ridiculous…I’ve paid premium for my ticket and you making an issue out of it is just plain lame. Use someone else who pays $49 for a ticket as an example…not me who paid premium for a non-stop flight when most would take 1-2 stops to Hawaii. I personally would pay extra for safety and always have. I have avoided air travel within the US as much as possible and when I do fly overseas, I pay premium for zero stops and pick my planes accordingly. Do you? Apparently not. If you want to… Read more »
Nick Barnard
Member

We’ll have to agree to disagree.

Although the odds of dying from Russian Roulette are at best 1 in 6. The odds of dying in an airplane crash are 1 in 9 million. I’ll take my odds at flying, thank you very much.

Armond
Guest

You can disagree all you want…but the fact remains that Boeing is involved in a coverup and flying in an aircraft that has structural problems reduces your great odds enormously.

Making silly comments about the odds of dying playing RR may be funny to you but ignorance is bliss and you never think it’ll happen to you.

Happy flying in those substandard 737’s!

Nick Barnard
Member

Thanks! I shall enjoy flying 737s, at least it didn’t crash when it was introduced at an air show…

Armond
Guest

No you’ll just have to worry about unrecoverable rudder deflections, fuselages ripping open, and constant over-running of runways….and all this in production aircraft with people like you on board!

And you really don’t understand the difference between a software glitch in pre-production aircraft and a KNOWN and purposefully covered up structural flaw in a production aircraft do you. As they say once more…ignorance truly is bliss…and we wonder why corporations get away with murder.

Happy flying!

Nick Barnard
Member

Well, we have to control the population on the planet somehow..

Armond
Guest

Ah….glad to see your true colors coming out.

Now I fully understand why your views and comments are so idiotic.

Nick Barnard
Member

I’ll remember to tag my sarcasm as such for you in the future. That being said, I still don’t understand your views. But at the moment I don’t care to, as I’ve already expended enough keystrokes on this topic..

Armond
Guest
I fail to understand your lack of understanding about the seriousness in the matter. Any sane person would never have views like yours about blatant safety violations in aviation. I have no idea what angle you have in all this but frankly telling someone you would be OK flying a structurally compromised aircraft whose manufacturing processes have been flawed and illegally covered up is INSANE. I agree..I too have wasted too many keystrokes on this…it’s clear it’s simply not getting through to you and either you have a vested interest in the matter somehow or your judgement is extremely poor.… Read more »
Nick Barnard
Member

737NGs have been flying for quite some time, they haven’t crashed. Thats my logic.

But here is also my logic, he who gets the last comment, wins.

Armond
Guest

They’ve never crashed??? LOL…ok….you win.

Now I know you really have no clue.

Nick Barnard
Member

Thank you for allowing me to win.

Yes, I have no clue about some things. Thats why getting people to eat my cooking is difficult.

Armond
Guest

Sure sure…you win.

Do some research and get back to us…till then…you have no clue…at least about 737 safety.

Have a great night! Oh and you’re a WINNER….DUH.

Nick Barnard
Member

Yes! I’m a winner!

Armond
Guest
The only asses here are you and Nicholas….you’re talking about peoples’ safety as if it’s no big deal. Disgusting viewpoint. Stick to the facts?? You’ve completely ignored what’s going…who the hell do you work for???? The FAA??? Boeing??? Give me a break…what YOU are completely overlooking is the FACT that the FAA has for decades been in bed with the manufacturers and you’re too busy looking at the microscopic issues and not looking at the bigger picture. It’s flown right over your head….pun intended. Please..YOU get your facts straight and realize how large this issue is…don’t be a strawman like… Read more »
Nick Barnard
Member
I’ve sat on responding to this comment for several hours. So I’m going to respond to one and only one specific statement “you’re talking about peoples’ safety as if it’s no big deal.” I take great offense that you would even insinuate this, let alone state it outright. Human life is important. It is one of the reasons why I have spent my own time and money (while unemployed even.) to ensure that I am certified in First Aid and CPR. I want to be prepared to do my best to deliver this emergency care if I need to. My… Read more »
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