April 5, 2011

Stress

Joan Lowy reports in the Atlanta Journal-Constitution on something that caught my eye for personal reasons:
Southwest grounded nearly 80 Boeing 737-300s after its jet leaving Phoenix lost pressure Friday, forcing pilots to make an emergency landing 125 miles away in Yuma. 
Friday's incident, however, raised questions about the impact that frequent takeoffs and landings by short-haul carriers like Southwest put on their aircraft and the adequacy of the inspections. 
Cracks can develop from the constant cycle of pressurizing the cabin for flight, and releasing it. 
Since there had been no previous accidents or major incidents involving metal fatigue in the middle part of the fuselage, Boeing maintenance procedures called only for airlines to perform a visual inspection. 
But airlines, manufacturers and federal regulators have known since at least 1988 that planes can suffer microscopic fractures. That year, an 18-foot section of the upper cabin of an Aloha Airlines 737-200 peeled away in flight, sucking out a flight attendant. ... 
Southwest appeared eager Monday to shift blame to Boeing. The airline said it had never been alerted to a potential problem where overlapping panels of aluminum skin are riveted together on the 737-300. 
"This is a Boeing-designed airplane. This is a Boeing-produced airplane," Southwest spokeswoman Linda Rutherford said. "It's obviously concerning to us that we're finding skin-fatigue issues."

I put this up because this is a lot of what my Dad, now 94, did during his four decades as a stress engineer at Lockheed: stare at pictures of microscopic cracks in airplane metal and try to figure out whether to tell the airline or the Air Force, "You know, funny thing, this plane turns out not to be quite as safe as we told you it would be when you bought it from us, so you'd better ground this expensive asset while we work out an expensive fix," or, "No problemo! No way is this plane going to rip apart in flight, sending everyone on board plunging to their deaths. Trust us."

Aeronautical stress engineering is a stressful job.


31 comments:

Anonymous said...

Aeronautical stress engineering is a stressful job.

Maybe some of those Chinese birth tourism babies can become future aeronautical engineers, Steve. Maybe even save a few white American lives. ;)

Anonymous said...

This is another reason I won't fly anymore. I don't trust the el cheapo Latin American airplane mechanics who have infiltrated US ground crews. It is only a matter of time before US air accident rates slowly ramp up to Brazillian levels.

Kylie said...

I always enjoy the stories you share about your dad.

Anonymous said...

James Dickey's wonderful poem comes to mind:

http://www.poetryfoundation.org/archive/poem.html?id=171431

Mel Torme said...

Steve, your Dad may have been physically looking at cracks in doing his research on crack formation and growth. I am sure, if he was an engineer, his job was not just to look at cracks all day and give a thumbs up or down as to airworthiness. It really doesn't seem like you know what engineers do.

Looking at cracks as part of a research program is one thing an engineer would do. That would be for the purpose of defining safe designs in general, such as how to make crack-arresting structures or how to safely make aircraft skin repairs. It would be up to a technician, mechanic, or aircraft inspector to look for cracks repetitively so as to approve and aircraft for service.

See, any material starts with imperfections in it from the get-go. It is up to the engineers with "fracture mechanics" backgrounds to make up protocols as to what length/shape cracks are still safe within a given type of structure. Whether the max. safe size is visible or not determines whether visual inspections vs. eddy current, dye penetrant, or other method is needed.

So, as commentor who calls himself "Anonymous" #2 has stated, a big worry is about who is inspecting the aircraft. It takes a lot of dedication, and resistance to being pressured.

Southwest does fly a lot of cycles compared to other operators of 737's. However, these -300's are not really, really old, like the -200's (ones with the old turbojet engines - the long ones.)

Anonymous said...

I always enjoy the stories you share about your dad.

Ditto. More stories about old-school engineers and the decline of crafstmanship in America. (I'm not being sarcastic.)

Anonymous said...

...But airlines, manufacturers and federal regulators have known since at least 1988 that planes can suffer microscopic fractures. That year, an 18-foot section of the upper cabin of an Aloha Airlines 737-200 peeled away in flight, sucking out a flight attendant...

"No problemo! No way is this plane going to rip apart in flight, sending everyone on board plunging to their deaths. Trust us."



My recollection was that the consensus opinion was that the stewardess didn't plunge to her death, but rather was engorged by a jet engine and turned into human ketchup [only they kept it quiet because they didn't want the public to know that].

TomV said...

Yan Shen:

Maybe some of those Chinese birth tourism babies can become future aeronautical engineers, Steve. Maybe even save a few white American lives. ;)

Or maybe they'll just stick with killing yellow Chinese lives through tainted baby formula.

Given the right policies, white and other natural-born Americans will fulfill America's engineering needs just fine.

Svigor said...

That year, an 18-foot section of the upper cabin of an Aloha Airlines 737-200 peeled away in flight, sucking out a flight attendant. ...

Jesus, what a way to go. Can you imagine that? Sucked out at 10k feet and falling all the way to the ground? Would you pass out from the lack of oxygen, or would you be conscious the whole way down?

Maybe some of those Chinese birth tourism babies can become future aeronautical engineers, Steve. Maybe even save a few white American lives. ;)

Indeed, all those heroic Chinese, sacrificing their cozy lives in the Chinese paradise so they can give birth to heroic white-lives-saving engineers here in the hell of America.

Of course, white Americans could do orders of magnitude more to improve their lot by sterilizing themselves and only "reproducing" by adopting yellow babies.

I wonder how many white parents look at their kids and wish they could swap them out for superior yellow kids?

Hey, we all know blacks deserve more help than whites. The altruistic thing for us to do is forgo the altruistic inva- er, help of the yellows, and divert it to Africa.

Why should the Chinese get all the altruistic glory?

icr said...

From what I've heard from retired US airline employees, aircraft maintenance is now (almost?)entirely outsourced.

Svigor said...

This is another reason I won't fly anymore. I don't trust the el cheapo Latin American airplane mechanics who have infiltrated US ground crews. It is only a matter of time before US air accident rates slowly ramp up to Brazillian levels.

Statistically, flying is safer than driving.

Statistically, my ass. I am not a statistic if I'm driving, or someone I trust is driving. On a plane, I am.

Svigor said...

My recollection was that the consensus opinion was that the stewardess didn't plunge to her death, but rather was engorged by a jet engine and turned into human ketchup [only they kept it quiet because they didn't want the public to know that].

Makes perfect sense, that. They didn't want the public to know she died instantly, painlessly, a moment after being sucked out of the plane; they wanted the public to think she died screaming, sobbing, and flapping all the way to the ground.

Anonymous said...

These things are a worry because they are not exactly random but happen in waves - the way house light bulbs tend to have similar but not predictable lifetimes. I'm not an engineer but can see this could be a diabolical problem when added to commercial realities and constrained supply of new planes.
Gilbert Pinfold.

Mel Torme said...

"... But airlines, manufacturers and federal regulators have known since at least 1988 that planes can suffer microscopic fractures" from the original article quoted, I assume.

Bullcrap. Fatigue cracking in metals has been known about since the late DeHavilland Comet of the late 1950's. It was determined to be the reason for 2 or 3 totally-fatal crashes, as the aircraft blew up at altitude (under the highest pressure difference) after too many cycles of pressurization/depressurization.

"My recollection was that the consensus opinion was that the stewardess didn't plunge to her death, but rather was engorged by a jet engine and turned into human ketchup [only they kept it quiet because they didn't want the public to know that]."

I agree with Anonymous over Svigor on this one. First of all, it can't be completely painless to go through the compressor, burner can, turbine, then exhaust nozzle of a turbojet engine, though it would all happen pretty quick - probably, if your life flashed in front of you, you'd only get to see yourself as a week-old baby. The poor girl may have hit the tail instead of the engine.

Seriously though, it's not a matter of which is truly more horrifying, but which sounds more horrifying.

"Statistically, my ass. I am not a statistic if I'm driving, or someone I trust is driving. On a plane, I am."

Well, this whole structural failure thing Steve wrote about has nothing to do with the pilots. If you are considering who is in front, you should take a look and see if the guy in the left seat looks old enough to be shaving regularly, and whether he seems to have a good command of English. No matter what else you can say about this country, we still have the most experienced pilots in the world.

As to your driving, first look in the rear-view mirror to make sure you are old enough to be shaving regularly. ;-) Also, you may be the best driver, but there are still drunken Mexicans, and many other people who drive worse than that when they are writing text messages. At least, in aviation, only a small percentage of serious accidents involve "the other guy".

TC said...

http://hillbuzz.org/2009/04/12/does-anyone-think-its-odd-the-medias-not-reporting-on-obamas-brother-raping-a-13-year-old/

Reams or Creams from My Brother.

EP said...

Here's an article on aircraft decompression, with some nice links to the Aloha Airlines incident:

http://newsfeed.time.com/2011/04/05/southwests-scare-when-a-plane-decompresses-what-happens/

Here's another nice article about the Aloha disaster and what happened to poor Clarabelle:

http://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243.

I have only experienced one aircraft decompression, on a Northwest 737, about 18 years ago. Nobody was hurt, but it was scary as hell. Northwest treated us like crap - they gave away our seats on our connecting flight! Guess they figured we'd all been killed in the crash. They had to pull passengers off the connecting flight to seat us, and they were surly as they could be about it, like it was all our fault. I am glad that Delta took them over and that the Northwest name will disappear forever. Good riddance.

Big Bill said...

"Maybe some of those Chinese birth tourism babies can become future aeronautical engineers, Steve. Maybe even save a few white American lives. ;)"

Oh, no thank you, Anon. It's very kind of you to offer, but we really shouldn't strip Red China of such valuable people.

I am sure they will be desperately needed to clean up the rivers, streams, landfills, dirt, ground and come up with modern technologies that can reduce the grotesque exploitation of the Chinese by the Chinese.

An better they do that in China for Chinese companies than let us Evil White folks own the IP here in the US.

So, thanks for offering, but, no, we really cannot take you up on your kind offer. I guess we will just have to learn to take care of ourselves, and you can share your wonderful talents with your people in China.

We would just feel too guilty to have you waste your life on such as we.

Anonymous said...

"Statistically, flying is safer than driving'

I heard, if you compare it by trips instead of miles, flying is not as safe as people thought. I don't know the stats.

jody said...

tough stuff. i knew a girl who went to CMU (i think it is now required to be called carnegie-mellon instead of CMU) and she took a job at boeing helping them design commercial aircraft that were more bomb resistant. this was sometime around 2000, before 9/11, but of course, long after many people had tried to blow up various aircraft in flight (with some succeeding obviously).

Anonymous said...

Outsourcing aircraft maintenance? That is genuinely scary. It does not seem that long ago that American union labor had a reputation for skilled craftsmanship. OK, you couldn't make them work any harder than they wanted to, but they could get the job done. What happened? The private sector unions have become irrelevant. I saw a pitifully small group of union picketers yesterday in downtown Syracuse, NY, while driving home from work. They had signs saying "Union Rights Are Human Rights" and other such silliness, but, as with the Druids, "no one knew who they were, or...what they were doing." It wasn't until I checked the news today that I saw this was part of the AFL-CIO's "nationwide rally" against the Koch brothers, or something. Pathetic. Jimmy Hoffa is spinning fast enough in his grave to produce "green power."

ben tillman said...

This is another reason I won't fly anymore. I don't trust the el cheapo Latin American airplane mechanics who have infiltrated US ground crews. It is only a matter of time before US air accident rates slowly ramp up to Brazillian levels.

Just yesterday I read something very disturbing at epinions.com:

I am Aircraft mechanic, and I bought the pool heater (250K BTU MiniMax NT LOW NOX with electrical starter no pilot) July 2006. It worked great for 2 seasons. Two days ago when I tried to start it for first time this year. I heard electrical arching, the blower stop, plastic burning smoke start coming out, and within 1 sec 6" of flame shooting out of the sides. I turn off my gas & electric, and the fire was still burning. I went in the house for the fire extinguishier, and put out the fire within 1 minute of flare up.

I could see the arched wire touching burner wall, and the igition module electrical flare from within. I call the fire dept. inspector, and he confirm my finding.

This fire should not happen if Pentair put conduit on the wire bundles, and install internal fuse for the electric control side of circuit. In the state of NJ, we are required to installed wire conduit going to the pool heater. Why Pentair is not installing conduit inside their heater?

Anonymous said...

SVigor wrote "they wanted the public to think she died screaming, sobbing, and flapping all the way to the ground"


That made me laugh for some strange reason- quite a visual but that's probably what I would have done- started flapping

Dan in DC

AllanF said...

Steve you always crack me up. Maybe to ask the question is to answer it, but why didn't you become an engineer?

From what you've shared of your background it sounds like it would have been the default choice.

Steve Sailer said...

I don't have the 3d visual brainpower for engineering. I'm okay with 2d, but I'm hopeless at 3d.

When I moved to Chicago in 1982, my father came over to my apartment in Santa Monica with a measuring tape and measured all my furniture. A couple of days later he came back with a diagram showing the smallest Ryder rental truck we could get to hold all of it. Like a 3d game of Tetris, he had figured out how to rotate ever piece of furniture to fit into the smallest overall volume. I would never have dreamed of doing that ahead of time.

headache said...

Stress engineering, known as Betriebsfestigkeit in German. I just completed a course in Aeronautical Engineering at a Germany uni, we went all over that topic. The subject really took off in Aeronautics with the serial failures of the BOAC Comets. Eventually they cyclically pumped and released water into a jet on the ground in order to figure out what was going on. The company stopped building escape hatches into the roofs of the planes and ovalized the windows. In addition they became aware of the fact that every punch rivet hole is laced with cracks. When you get into an aluminum plane it is partly failed already.

But the new gen composites by Boeing and Airbus have other problems, such as destruction of the matrix upon hitting birds or flying objects on the runways, or falling mechanics tools.

I studied aeronautics in part to overcome the fear of flying, it helped somewhat but also increased my doubts, as I now realize there are engineers like myself and technicians sitting on the other side who are human and make mistakes.

Anonymous said...

When I moved to Chicago in 1982, my father came over to my apartment in Santa Monica with a measuring tape and measured all my furniture. A couple of days later he came back with a diagram showing the smallest Ryder rental truck we could get to hold all of it. Like a 3d game of Tetris, he had figured out how to rotate ever piece of furniture to fit into the smallest overall volume. I would never have dreamed of doing that ahead of time.

That sounds so Japanese!

JSM said...

Ben Tillman,

That post IS disturbing.

Not only because the pool heater was poorly designed, lacking fuses, etc., but because the aircraft mechanic in NJ writes like he's functionally illiterate.

Kylie said...

"When I moved to Chicago in 1982, my father came over to my apartment in Santa Monica with a measuring tape and measured all my furniture..."

Great story, thanks.

Ligsinn said...

Your dad's 94? Lucky guys, both of you. God bless.

CharleszMartel said...

I remember that Aloha Air incident. The plane landed safely ( I believe it was a woman pilot or first officer- not sure) with the comment that the plane felt wobbly, as the rigidity of the fuselage had been seriously compromised, obviously. I believe the stewardess's body was recovered from the ocean, and I don't think a turbine would still be functioning smoothly after ingesting a human. My recollection is that the plane's engines continued to function normally. It's probably an urban myth that she died by engine ingestion.

Anonymous said...

you love your old man. It's cool. Kill some commies for Christ, man.