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http://www.russianspaceweb.com/proton_glonass49.html http://www.russianspaceweb.com/proton_glonass49.html > By July 13, investigators simulated the improper in
by greglindahl 8y ago
http://www.russianspaceweb.com/proton_glonass49.html http://www.russianspaceweb.com/proton_glonass49.html
> By July 13, investigators simulated the improper installation of the DUS angular velocity sensors on the actual hardware. As it turned out, it would be very difficult to do but not impossible. To achieve that personnel would need to use procedures and instruments not certified either by the design documentation or the installation instructions. As a result, the plate holding the sensors sustained damage. Yet, when the hardware recovered from the accident was delivered to GKNPTs Khrunichev, it was discovered that the nature of the damage to the plate had almost exactly matched the simulated version.
- WalterBright 8y agoNot only should it be impossible to install the part without doing some machine work, it should be easily inspect-able to see if it is right. Hence the arrows and color coding. For aerospace hydraulic actuators, where installing the lines backwards will crash the airplane (and this has happened): 1. inlet and outlet have different size ports 2. one is a left hand thread, the other right hand 3. the lines are not long enough to reach the wrong port 4. they're color coded, with arrows 5. the acceptance test tests that the actuator goes the right direction. In fact, this is often part of the preflight checklist. Just for fun, take a look at the connections on your car's battery. It's usually easy to hook them up backwards - the cables are not color-coded, they're long enough, they use the same connectors, the + and - is easily obscured by dirt, etc. Hooking them up backwards will set your car on fire. (google it!) When I hook up cables, I always find the one that connects to the engine block, that way I know it is -, and scrape off the dirt to make sure I find the - post.
- greglindahl 8y agoSame article: > By July 9, it is transpired that investigators sifting through the wreckage of the doomed rocket had found critical angular velocity sensors, DUS, installed upside down. Each of those sensors had an arrow that was suppose to point toward the top of the vehicle, however multiple sensors on the failed rocket were pointing downward instead.
- WalterBright 8y agoThis is why the guy who inspects and signs off on the work must not be the same guy who does the work. Yes, the article confirms what I am talking about.
- ridgeguy 8y agoBackwards installation of G-switches crashed the Genesis probe on its return to earth [1]. [1] https://en.wikipedia.org/wiki/Genesis_(spacecraft)#Mishap_Investigation_Board_(MIB) https://en.wikipedia.org/wiki/Genesis_(spacecraft)#Mishap_In...
- WalterBright 8y agoFrom the photo of the switch, I'd say the package design could use improvement. The orientation of it is not obvious.
- ridgeguy 8y agoJust so. Twenty minutes of a designer role-playing an assembly tech installing those components (with the mindset of trying to fail) might have gotten us a "this can only fit one way" result.
- hinkley 8y agoThis part was news to me: > On January 6, 2006, Ryschkewitsch revealed that a pre-test procedure on the craft was skipped by Lockheed Martin, and he noted that the test could have easily detected the problem.
- grepthisab 8y agoOh geez I did this one time on my first car when I was 16 or so. Transposed the battery connects. It sparked and was just done for a second, but fried the whole ECU, battery, alternator, and more. Very costly lesson I will never repeat.
- justtopost 8y agoSounds like the real failure was your main fuse, or lack therof. That should blow before all that other stuff. Safeguards are THE lesson.