This story reminds me of a physics professor that refused to give partial credit on complex problems. His reasoning was that in real life even tiny mistakes like an errant punch slug can have disastrous consequences. We as engineering students had to learn that there is no almost wrong or almost right.
The problem described would have been in the autopilot system, not the primary flight controls. As kenish correctly notes, C-130's have hydraulically-booseted manual controls, not fly-by-wire. The Functionl Check Flight crew would not have the autopilot engaged during takeoff, but could have had an unexpected surprise when they engaged the autopilot in flight. However, they could have quickly disengaged the autopilot, and most autopilots have clutches that will allow the crew to overpower the autopilot inputs with the cockpit controls.
TJ, the metallic sliver was likely introduced by drilling of the structure near the harness, which introduced shavings into the harness that were not properly cleaned up. Have seen this several times. You would be shocked at the lack of QA at some of the military overhaul depots. One major depot that one of my aircraft went through had no independant inspection. They relied on the technician performing the work to inspect his own work (all in the interest of cost savings).
I always preflight my plane, truck and motorcycle. On the C-130 in the article a preflight probably would not have found the problem. The elevator isn't visible from the cockpit, so "Flight Controls Free and Correct" would not help. The first sign of trouble would have been at gear retraction as the author pointed out.
I do wonder a bit on the veracity....the flight controls in a C-130 "Herky Bird" are mechanical...pushrods, bellcranks, cables, and pulleys. AFAIK even the latest "J" version is not fly-by-wire.
After reading the story I don't believe that Lockheed designed a single point failure mode of the primary flight control system. All aircraft are designed with redundancy based on risk. Flight control failure though low in risk is high in severity and thus qualifies for redundancy.
The longer I am in engineering, the longer I realize intuition is as important as math and numbers. Learning to listen to your intuition is as important as learning theories. There are so many interactions in a system, is impossible for anyone to systematically troubleshoot. Sometime when you are faced with a problem, is best to stand back and ask yourself what do you think. What does your little voice tell you.
It is always better to ask stupid questions before the accident than having to testify before the Accident Review Board.
If doesn't look right, investigate until you're certain there is no problem or there is one. Is someone's word that "it's good enough" equal to an aircrews' life?
Good points - I agree it is always more convincing to show than tell. We as engineers are often too busy to spend the time to figure out how to show - it's not always easy. But definitely worth it - especially when it comes to mission critical issues.
The spirit (or should I say ghost) of Richard Feynmann lives on.
I'm really, really surprised that the sliver wasn't accounted for during the modification. Aircraft maintenance and fabrication is normally much more focused on accounting for everything that goes in and out of an aircraft. Lost fasteners must be found and so forth.
For 3D printing to make the jump from rapid prototyping to manufacturing, engineers will need to find easier ways to move products from their CAD screens to their printers.
Gigabit and PoE are two networking technologies moving ahead in tandem as industrial users power remote Ethernet devices such as IP security cameras at 1,000 Mbps over existing CAT5 cable.
New versions of BASF's Ecovio line are both compostable and designed for either injection molding or thermoforming. These combinations are becoming more common for the single-use bioplastics used in food service and food packaging applications, but are still not widely available.
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For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This radio show will show what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.
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