Text 1994, 228 rader
Skriven 2005-08-16 15:39:48 av mark lewis (1:3634/12.0)
   Kommentar till text 1991 av WAYNE CHIRNSIDE (1:123/140)
Ärende: NASA, shuttle, anyone?
==============================
-> -> not according to what i've seen... it was the backup sensor 
-> -> to the backup sensor that failed in the testing done during 
-> -> the launch countdown... they were unable to reproduce the 
-> -> failure during later testing after going into the system to 
-> -> try to track down the failure...     

->  WC> Every sensor is the backup for the other three and that's 
->  WC> a fact. 

-> oh? so which one is the primary? and where is this fact stated?

 WC> All four are the primary and three  are the backups to the one 
 WC> that may give an anomalous reading.

hahaha... somehow, that sounds quite political ;)

ok, so there was one giving an erroneous reading... the other three were giving
proper readings... so what was the problem?? why the big deal if three are
backups to one?? do you see what i mean and what i'm saying?

[trim]

-> right... however, the problem was that the sensor(s) were
-> indicating no fuel
-> when there was a full tank... so different problem, actually...

 WC> Well as thye never determined _what_ caused the sensor problem 
 WC> there's no way to predict any way a future failure might have
 WC> manifested itself.

ok, so until the problem happens again, you carry on... why worry about broken
eggs until you get some to put in the basket??

-> -> the failure was a "no fuel" indication when
-> -> the tanks had fuel... not an indication of fuel when there was none...

->  WC> Any intermittent failure is unpredictable and with a half million 
->  WC> gallons of liquid hydrogen and oxygen there's little room for
->  WC> error. 

-> with a _known_ full tank and one sensor telling them it is empty,
-> that sounds pretty predictable to me...

 WC> That a critcal compnent had failed yes.
 WC> Sometimes the sensor indicated fuel, other times not.

critical? there are four of them... you've already stated that three were
backups... seems to me that if three are giving the same reading and one isn't,
you ignore the one that isn't and carry on... that's pretty much what's been
stated, right??

[trim]

-> yes, i've extremely aware of all this (other than the engineer 
-> being fired)... i have archived recordings and texts of much of 
-> it, if not all of it... i'm very into this stuff and have a couple 
-> of satelite dishes set up where i can specifically acquire the NASA 
-> TVRO signals... the 10 foot mesh has two sets of recievers connected 
-> so that i can watch/record two channels off one bird... the other 
-> dish is a direct tv dish that i get the same as one of the channels 
-> off the 10 foot mesh... i won't even mention the "tracking" dish i 
-> have connected to a soundcard and tracking software for grabbing 
-> images and other data transmitted O:)                                

 WC> Sure seems you're into it!

i'm actually into quite a lot of things...

 WC> I've followed the space program since Atlas and Redstones
 WC> and the first Mercury capsules.

 WC> I've also looked into the Bell X-craft program that was before my
 WC> time by researching the internet.

hear that... kinda pretty much like myself...

[trim]

-> -> i'm not worried... i was saying that there does not have to be a
-> -> rollback to fix a problem... i left off the word "you" in front of 
-> -> "don't"...

->  WC> You do if you want to go inside the tank where the fuel sensors are
->  WC> and actually diagnose what's wrong with them, or so said NASA. They
->  WC> flew on a wing and a prayer instead.

-> obviously you don't because they didn't... they pulled the sensor(s) and
-> connected them to testing hardware and had at them for days... 
    
 WC> Nope, they wrang out the wires, swapped pairs and ran diagnostics.
 WC> To actually examine the fuel sensors one has to empty the tank,
 WC> clear it and enter the tank and that would have to have taken place
 WC> in the vehical assembly building.

they did empty the fuel tank(s)... they always do when they abort a launch...
the conference that i saw said that they pulled the sensor that was reading bad
and put it in test gear... it tested with no faults... they swapped it with
another sensor and got the same readings... then they went back to the ship,
installed everything with the test gear in the line and ran tests on the whole
assembly... the test gear in question was such that they could introduce faults
and vary the resistance of the lines for the various tests... everything rang
true and they had no other options other than to put everything back into
flight status and go on with the countdown and normal procedures... one of
those procedures was that same test that the sensor faulted on the first
time... it didn't fault this time and so they launched ;)

-> when they discovered nothing, they put them back in place and tested 
-> again for more days... still nothing showed up...  

 WC> They never moved them out of place, they're _inside_ the tank. They
 WC> swapped wire pairs, ran diagnostics and speculated on
 WC> what _might_ have been wrong with the bad sensor.

that is _not_ what was stated at the conference(s) that i saw... they still
don't know if there every was a "bad sensor"...

-> oh, and who said they had to roll back to get inside the tank(s)??
-> i'm sure there are accessible man hatches somewhere on the 
-> vehicle... at least if the sensors are inside the tank(s)...         

 WC> Source: NASA as reported by local NBC affiliate.

we all know how reporters get things wrong and/or slightly twisted... too many
of them are concentrating on verbiage and such... most reporters do nothing
more than piss me off trying to be wordy and such... i've had more than one
reporter (and editor, AAMOF) turn my own statements around by altering one or
two words, repeating what i've said in another order than i said it, or even
dropping key portions of what was said...

[trim]


->  WC> They said they would fly with three operating sensors in direct
->  WC> violation of safety regulations requiring all four be working. 

-> interesting... i dunno if i'll go digging about for that, though...
-> it is not that important, really... the mission flew and was highly 
-> successful... i have absolutely no problem with that at all...

 WC> The backup orbiter's fuel tank sensors had shown the same erratic
 WC> behavior previously.

i've not seen or heard anything about that...

-> ->  WC> It just happpened the sensor didn't fail during the runup to
-> ->  WC> launch, very fortuitous.

-> -> are you positive that it was a sensor failure? they aren't...

 WC> No way to be *positive* as the sensors were never examined.
 WC> I'd _guess_ a grounding problem but that's all it'd be is a guess.
 WC> If I had the go - no go responsibility I wouldn't launch on a
 WC> guess. 

and we waste millions more of an already dwindling budget that's getting cut
smaller and smaller...

 WC> In all likelyhood one more catastrophic failure kills the program.
 WC> There are 19 more needed launches to finish the international space
 WC> station and one Hubble service call and that's cuting it close. 

personally, i think they screwed the pooch by not getting on the ball with
other programs and vehicle development...

 WC> It also puts the odds based on past performance of another
 WC> catastrophic failure at near .60 certainty.
 WC> They could all go off flawlessly or we could have another shuttle
 WC> break up.

there's only been two out of how many lanuches?? yes, considering the loss of
life, that's two too many... however, the percentile is a lot lower than 60%...
60% is a major b0rkin'...

[trim]

->  WC> I finally found the ground fault, it was in the high - low beam
->  WC> selector button on the floor and a new one cured the problem.

-> glad you found that or we'd not be having this _friendly_
-> discussion today ;)

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

-> -> ->  WC> Now the tank's burned up returning to Earth we'll never 
-> -> ->  WC> know why the sensor malfunctioned.

-> -> -> one suggestion was a ground problem because the problem never
-> -> -> happened after the initial discovery... could also have been a 
-> -> -> loose connection... either way, they apparently fixed it while 
-> -> -> getting to it and studying it...              

 WC> Or not, we'll never know.

and the mission was successful... the $$$ invested weren't wasted or otherwise
flushed down the crapper... that's a "GoodThing<tm>" ;)

[trim]

-> yup... i've been a ground more than i care to think about... i 
-> really hate being the ground path when discharging picture tubes... 
-> that's one bite that hurts like hell... not only is high voltage a 
-> problem, but so is high amperage... i can cause some real pain with 
-> 9 volts and a high amount of ampreage O:)
                               
 WC> Make up a discharge wand using high tension high voltage wire like
 WC> the anode wire, put a high value resister in line, have an
 WC> insulated handle and flat conducting surface to slide under the 
 WC> anode cup to discharge prior to pulling the anode lead.

BTDT, have several tee-shirts... however, i don't know that i actually use a
resistor... i don't like to have to wait for the discharge... spark that puppy
to ground and let's get on with the job O:)  anyway, each time it has happened,
there's been something that has distracted me and i'd get hit... oh well... i'm
a glutton for punishment at times O:)

 WC> Being a tad paranoid about such things I used a series high value
 WC> resistor in series with a lower value one with a neon bulb 
 WC> across the smaller resistor as a visual indication of discharge. 

do you have a schematic? sounds like something that would definitely work...
especially with an indicator that the is no more charge stored in the tube...
that's always been my biggest fear... and why i ground the tube even after
discharging it... i don't like the stuff building back up and surprising me,
either ;)

)\/(ark

 * Origin:  (1:3634/12)