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Engineering mistakes

Engineering mistakes

RE: Engineering mistakes

The NE blackout in 2003 was finally determined to have been caused in the US, not Canada, as first originally broadcast.

I think I seem to recall Ohio, but may be mistaken.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

I disagree with the assertion that all these were stupid engineering mistakes.  I think the problem with the Zeppelins is a good example- they just didn't have the technology they needed to properly analyze these things, and performance requirements didn't allow a "when in doubt, make it stout" approach.  People always criticize them for using flammable hydrogen in these things, but a typical jetliner is a powderkeg by comparison.  In the power grid problems, you're dealing with a very involved system, and even after the event, it was a major challenge to figure out when wrong.

RE: Engineering mistakes

Often times, it's only a stupid mistake after the fact.

Most of the time, when going forward, it seems perfectly legitamate.

A modern day jetliner is an explosive device - the Twin Towers were brought down by jet fule burning.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

Several of those descriptions on the website are fairly inaccurate.

Hg

Eng-Tips policies:  FAQ731-376

RE: Engineering mistakes

If the human race had not made those and similar mistakes and had not learned valuable lessons from them, where would we be today?  Not nearly where we are today!

Good luck,
Latexman

RE: Engineering mistakes

Ash.. said, "Often times, it's only a stupid mistake after the fact"  There is a lot of truth to this.  My boss said to me one day, "the checker is more responsible than the originator."  Quite correct I think.

I work on aircraft, specifically structure, wings, critical stuff.  But one day the boss came to me about a pretty bad mistake I made.  He scolded me up and down, blah blah.  I then told him, "the checker is more ...."  He had checked my report.  Quite amusing I think.

Anyway, my first 3 years of college were to become a aircraft mechanic.  I continued my education to become an engineer (with the thought that I can always turn wrenches if I wanted to).  My point is that I had my most valuable course ever during my mechanicaning class.  The class was recip engine troubleshooting.  This was after most all of our mechcanic type classes.  Thus, we all though we knew everything.  The teacher showed us how to run up engines (on engine test stands).  Showed us the most typical problems (vacuum leak, timing off, etc).  Then one day told us he had placed problems in the engines and we were to trouble shoot and fix.  Then he said that we are all way too complacent and that complaceny KILLS.  "you don't realize this but it's true."  Well, we all pretty much thought he was full of @!#.  We all walked out to our engines thinking no problem.  Well no team fixed the engines (after several hours of desparately trying to solve the issue).  Walked away with our tails between our legs and the most important lesson learned ever!  I believe that one teacher has saved many many lives.  Remember that complaceny kills.  Also, engineers severly underpaid! (taken for granted if you will).

RE: Engineering mistakes

WRT Zeppelins, I think it's been established that the thick layer of aluminum- powder- filled dope on the outer skin was a major contributor to the Hindenburg fire (hence the color; hydrogen flames are colorless), and a good candidate as the ignition source, given a static discharge.  The structure seemed to perform just fine, until weakened by ground impact and then heat.
 
My best tech ever was an old aircraft mechanic, and he expained the aircraft mechanic anti- complacency incentive program; random rides in the airplane you've just fixed.

Mike Halloran
Pembroke Pines, FL, USA

RE: Engineering mistakes

Quote (MikeHalloran):

My best tech ever was an old aircraft mechanic, and he expained the aircraft mechanic anti- complacency incentive program; random rides in the airplane you've just fixed.
Once upon a time I work for the US Navy (civilian employee) but was flight qualified.  Every time I strapped into an ejection seat I knew that the person (at that point invariably a man, but not necessarily that gender consistency today) who had packed the parachute in the ejection seat had jumped out of a plane wearing a random chute he had packed.  The fact that chutes one would wear to jump out of a plane were different, and packed differently, than ejection chutes was a minor issue, but at least the chute was packed by someone who had at least packed one chute properly.

RE: Engineering mistakes

Mike, there were a number of dirigibles that did just break up in various ways in storms and whatnot- I didn't have the Hindenburg in mind particularly.  Of course, they didn't have near the capabilities in structural design that modern engineers do, but the bigger problem was finding the loads to design for.  Finding accurately all the possible forces on a 1000' airship in a storm would be difficult today, much less 80 years ago.  Example:  Consider the damage to the roof of the Superdome.

RE: Engineering mistakes

Reading up on the Vasa- interesting stuff there.  But it didn't just sail out and sink-  "There was a sudden squall, her gun ports were still open having just fired farewell, and when she listed heavily to port, the gun ports sank below water level and water gushed in. It took only a few moments for her to sink. (This is very similar to what happened years earlier with the Mary Rose, an English vessel, sunk in 1545.)"  So not quite as stupid as that first website makes it sound.

RE: Engineering mistakes

I doubt that modern engineering could make a storm- proof airship; they could more quickly prove it impossible, even with modern materials.  Flying an airship into a storm intentionally is the height of hubris.

The airship captain usually has the option of flying away from the storm; fabric covered buildings don't.

Mike Halloran
Pembroke Pines, FL, USA

RE: Engineering mistakes

The R-101 is the subject of a book titled "The Airmen who Would Not Die"
If I remeber correctly ( it's been a while since I read it) the ghost of the crew of R-101 somehow got the story of why it crashed to the builders and flaws in sister ships were corrected.  If the ghosts hadn't interviend we might never had the novel and movie "On The Beach" as Nevil Shute was a crewman on one of the British lighter than air ships.


http://www.amazon.com/gp/product/0399122648/103-3214727-3080646?v=glance&n=283155

RE: Engineering mistakes

I was watching "Engineering Disasters" on "Modern Marvels" a night or two ago.  One of the cases they talked about was the Hyatt Regency walkway collapse.  There, a detail was revised, got shuffled around and never actually checked- more of a management oversight than an outright engineering goof.  But one of the people on the show was the structural engineer who had sealed that detail.  His attitude was "There were a lot of ways blame could be placed, but I'm the one who sealed the drawing and the buck stops here."  That would be a hard statement to have to make in those circumstances, and I admire his willingness to discuss the issue.

RE: Engineering mistakes

The Kansas City walkway had two fundamental problems.  One compounded the other.

The first is that the structure was underdesigned.  There was ZERO margin, based on the original design.

This was compounded by the fact that the contractor changed the fabrication drawings and the engineer(s) signed off without correcting the drawings, which caused a multiplication of the load at a joint that was undersized to begin with.

That's why the engineers lost their licenses for gross negligence, both in the poor initial design and negligent checking of the drawings.

TTFN



RE: Engineering mistakes

Boy there’s lots memory work in this post and the ensuing thread.

I don’t believe the reference to the DC-10s problems in Wired’s original article was presented accurately.

There was a book, Destination disaster: From the Tri-Motor to the DC-10, the risk of flying (Paperback) that discusses the issues with the DC10. My memory tells me it was a race to market between the L1011 and the DC10. I believe the book also alleges failures on the part of the FAA because they didn’t issue an Airworthiness Directive based on verbal assurances from Douglass that the cargo door problems would be corrected.

Kwan, I relate to the engine troubleshooting exercise because I remember doing that in A&P school after I got out of the service. The crew in my engine overhaul class was me and two other ex-marines. I know we found every fault but one (the one that fixed itself). The instructor jammed a wad of paper in one of the ignition leads and it burned through on it’s own.

See this old snapshot if you like. East Coast AeroTech (1978) ->

http://kontikilink.home.mindspring.com/ECAT.jpg

davidbeach, I like your story too. When I was in the Marine Corps, I was one of those parachute riggers. I mostly worked on A6 and A4 gear, 1973-1977. At the squadron level, we didn’t pack them. We did do a lot of 7 day inspections.

I must have done a thousand of them between our 12 airplanes. I was very conscientious about them too. I hand pumped the canopies open, looked at the 12 or so inspection points, and pumped it closed. When I climbed down, if I determined I didn’t remember what I had looked at, I’d pump it open and do it again.

In my 4 yrs of active duty, I found two parachutes that were packed incorrectly. Of course, I had them pulled and repacked. These were fairly sophisticated chutes for those times. Not the ordinary “rag in a bag.” They were zero zero capability chutes designed to save the crew at zero airspeed and zero altitude. I think it was fairly innovative for those days.

Sorry to indulge so many old memories. I was in awe a lot more back then.

RE: Engineering mistakes

One of society's problems today is that the insurance companies insist of the details being hidden under confidentiality agreements. How can this be? Surely as engineers we can only learn from our mistakes, If they are hidden no one learns.

The high profile matters may have judicial or senate enquiries and be in open forum. Day to day failures that are settled by insurance companies are hidden. How many of my contracts have confidentialty clauses that prevent me going public? 100%!!

Well I am at the end of my career and dont care. If I see bad things I bring them to the fore, not necessarily publcally but I let people in industry know. As engineers we need to speak out and get the truth out there. There are plenty of ways. Internet blogs are probably the fastest and most anonymous.

Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng
www.waterhammer.bigblog.com.au

RE: Engineering mistakes

Nevil Shute Norway was more than a crewman, he was one of the engineers working on the design as related in his auotbiography "Slide Rule", which gfetaured in another thread about government Vs Private sector research... the differences between the R100 and the R101 were significant.
Also, another thread on Engineering mistakes pretty well covers this ground and I think we should make clear a distinction between envelope pushing, unexpected outcomes and "should have known better" mistakes, the web link seems not to make that distinction.

JMW
www.ViscoAnalyser.com

RE: Engineering mistakes

The article is incorrect about the Citigroup Center Tower. The Citigroup Center Tower required the changes due to quatering winds not being considered in the original design. As was standard, analysis was performed with wind on each face but not to the corner of the building.

The buiding had the main supports in the center of the walls, not at the corners. This was to preserve an historic church I believe. Applying wind to the corner caused half the braces in the building to unload and the other to recieve double load.

To his credit, the engineer is the one who discovered the problem and brought it to the attention of the proper people. It was and still is an innovative design.

Rik

RE: Engineering mistakes

I'm surprised that Skogs hasn't chimed in on the Vasa, Scandinavian honor, etc.

Some interesting factoids:
http://www.vasamuseet.se/Vasamuseet/Om/Skeppet/Darfor%20sjonk%20Vasa.aspx?lang=en

Near as I can tell, the only stupid engineering mistake was taking the job in the first place.  This is clearly a "pushing the envelope" case, coupled with an Admiral ignoring a failed acceptance test, and a captain taking too many risks on a maiden voyage.

TTFN



RE: Engineering mistakes

It always annoyed me (while watching Modern Marvels: Engineering Disasters type shows) that so many of their "engineering" faults seem to be not design flaws in the slightest.

An example that comes to mind, there was a piece on the Sherman tanks from WWII, which went on and on about how they were so inferiorly designed to the German tanks of the day.  Engineering failure this and design failure that.  Unless I missed something, the designers and engineers did their jobs to the letter.  If they were provided with faulty design inputs, how is that their fault?

For instance, if the customer (US army?) says we need armor to stop a 20mm shell and the designers deliver - is it their fault that the Germans are using 40mm shells?  Is this an engineering disaster?  

RE: Engineering mistakes

The kill rate of US tanks vs German tanks was about 1:7 I had heard. For every German tank killed, the US lost seven.

The replenishment rate of US tanks to German tanks was 16:1. For every German tank replaced, the US replaced 16.

The US was fighting on industrial efficiency while the Germans relied on military efficiency.

The US tanks were desgined for superior manufacturing speed, not superior field performance.

The numbers may not be exact, but I believe the relativeness of the numbers are correct.

Then again, this may be an "urban legend", so reader beware.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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RE: Engineering mistakes

Which came first, the Mary Rose or the Vasa?

JMW
www.ViscoAnalyser.com

RE: Engineering mistakes

Mary Rose

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

The Vasa evidently sunk during her maiden voyage.

The Mary Rose sunk during battle towards the end of her life expectancy. Evidently, she was becoming obsolete as a war ship.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

But, if you read closely, they sank for identical reasons, that being the lower gunports getting inundated.

Quote:

Having outrun the rest of the fleet, and coming under fire, she put about, both to fire her broadside guns, and to wait for support, when a sudden gust of wind pressed her over. As her low gun-ports had not been closed, she quickly filled and sank

 Evidently, the news hadn't made to Sweden prior to the construction of the Vasa.

TTFN



RE: Engineering mistakes

Oh, and the Vasa's captain made the same claim about a sudden gust of wind, etc...

TTFN



RE: Engineering mistakes

Well, evidently, the English were good at keeping classified information classified (Navy Intelligence).

It seems that no other English war ship suffered from this design.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

US Army doctrine in WW2 was not to use tanks against tanks. They were primarily intended for exploiting weakpoints in the defensive lines, and for shooting up the supply network. This is called cruiser warfare. The British explicitly designed different sorts of tank for infantry support, cruiser warfare, and tank destroyers. It was only as the size of tanks reached 50-60 tons that all three roles could be met at once, as tanks evolved into MBTs.

The Sherman also had to fit in with the loading gage of various bits of transportation. To transport a German tank on the railway first you removed the main drive wheels and the tracks, and then fitted narrow ones. At the other end of its journey you reversed the process. Crazy.

Also notice that the Sherman was basically the well proven chassis of the Lee/Grant, with a new top. That was not the only reason it was reliable, but it was one of the reasons. The chassis of PV and PVI were new each time, and the lack of reliability was crippling. Tanks were gaining weight at a rate of about 30% per year during the war, so one based on an old chassis was likely to be rather light and hence under armoured compared with the clean sheet of paper designs. See

http://www.geocities.com/greglocock/gallery/tanks.jpg

Sherman was not perhaps a brilliant design in retrospect, it was evolutionary not revolutionary, but it was good enough. The Allies made far worse engineering mistakes than the spec of the Sherman.

Cheers

Greg Locock

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RE: Engineering mistakes

William Mulholland
Quite the man, in my view. For those of you who have or have not been to Southern California might know that it is a desert, yet it flourishes with the benefit of water provided by the vision and engineering for-site of William Mulholland. He took full responsibility  for the failure of the dam. Critics also concede that at the time the technology was limited to ascertain poor conditions of the bed rock. For the rest of us his vision of water canals and aqueduct system to feed Southern California it's water needs was truly genius.
PS: I live in one of the small towns that was devastated by that flood.

Stupid Engineering Mistake or just good viewer ratings.

I'll stand by Mulholland.


 
   

Best regards
pennpoint

RE: Engineering mistakes

Thanks Greg and Ash, but I should've known that bringing up tanks would cloud the issue. medal

Is the designer/engineer responsible for validating the appropriateness of the design inputs?

I'm not talking breaking laws of physics, but why is it called an engineering disaster if the end-user did something completely foolish and unanticipated, causing failure?

RE: Engineering mistakes

Because it is easier to blame the engineering?

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

As in the case of the Vasa, would you tell the king he's an idiot?  Likewise, the admiral declined to tell the king that his expensive toy was a white elephant after failing its stability test.

We get that situation very often in aerospace, particularly since the customer community no longer has the in-depth expertise they used to have.  

We have customer now that insists on requiring a laser that puts out nearly double the required power, but also wants it in a small volume and weight, but doesn't want to pay to break the laws of physics and reality.

TTFN



RE: Engineering mistakes

What is the going rate for breaking the laws of physics and reality currently?  Tee Hee Hee flip

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Engineering mistakes

Would someone explain the role of "aerodynamics" on the Skylab panels? Is space not a vacuum? Or could the author have meant "thermodynamics".

RE: Engineering mistakes

Thanks for the clarification.

As an aside, one thing that grates is the smug tone of some engineering critiques. As if the critic would never have made such a foolish error! But then, the best way to avoid criticism is to do nothing.

RE: Engineering mistakes

In fact, the latest Mars Reconnaissance Orbiter is playing aerodynamics over Mars even as we speak.  They're using the outer atmosphere drag to convert their elliptical orbit into a more circular one.

TTFN



RE: Engineering mistakes

Some of the mistakes mentioned on the site by the OP were made because the people involved didn't know any better, or had know way to know any better.  That's how we learn and advance our technology.  

Others, such as the Kansas city Hyatt, were just plain irresponisble.  Someone should have known better but either didn't check or didn't care.  That mistake was preventable and within our realm of knowledge to do so.  All you learn from that is how to save a few dollars at the expense of lives, and hopefully we all learn not to do it again.

RE: Engineering mistakes

It's not at all clear from the record that the Kansas City engineers were even concerned about cost.  They were simply negligent.  The contractor's change was motivated by cost, because, without the changes they made they would have had to thread something like 40 ft of stock, which would have taken both time and manpower.  Even if the contractor hadn't made the change, the basic design was insufficiently margined.

TTFN



RE: Engineering mistakes

jabberwocky,

I hear you about the engineering disater shows. I was watching one talking about some houses in CA sliding off a hill. On the show they stated that all the homes that moved were built before engineering was required (ie NO engineering). How is it an engineering disaster, if there was no engineering?

Rik

RE: Engineering mistakes

FYI

Purity Distilling Company tank, 1919

This is a topic in the new PE magazine from NSPE and will be a topic at the conference in Boston.

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