Engineering mistakes 1

[21121956]

Hello everybody:

Sometimes, something is wrong.
Just read this

http://www.wired.com/wired/archive/14.06/start.html?pg=9

 

[Ashereng]

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?

 

[JStephen]

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.

 

[Ashereng]

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?

 

[HgTX]

Several of those descriptions on the website are fairly inaccurate.

Hg

Eng-Tips policies: faq731-376

 

[Latexman]

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

 

[Kwan]

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).

 

[MikeHalloran]

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

 

[davidbeach]

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.

 

[JStephen]

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.

 

[JStephen]

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.

 

[MikeHalloran]

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

 

[BJC]

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

 

[JStephen]

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.

 

[IRstuff]

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

 

[kontiki99]

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.

 

[stanier]

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

http://www.waterhammer.bigblog.com.au

 

[jmw]

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

http://www.ViscoAnalyser.com

 

[rday]

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

 

[IRstuff]

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 sjonk Vasa.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