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#240
by
Ford Mustang
on 09 Dec, 2007 12:10
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About 15 minutes left with draining of LOX. At that point, they may sit for a few minutes on the LH2 (and not drain right away).
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#241
by
dabella
on 09 Dec, 2007 12:11
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How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
Dan.-
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#242
by
dember
on 09 Dec, 2007 12:11
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Anyone think we can get off before the 13th? I'm doubtful.
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#243
by
joncz
on 09 Dec, 2007 12:12
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Prior to Challenger it was 3/4. Post-Challenger they went to 4/4 until they started having ECO problems. Then they revisited the requirement and went back to 3/4.
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#244
by
DaveS
on 09 Dec, 2007 12:13
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dabella - 9/12/2007 2:11 PM
How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
Dan.-
That is what they don't know! Could be wiring, could be the sensors. They don't know.
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#245
by
shuttlefan
on 09 Dec, 2007 12:13
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dabella - 9/12/2007 7:11 AM
How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
Dan.-
The work itself isn't particularly difficult but it would result in a long delay as they'd have to rollback to the Vehicle Assembly Building to actually do the work... The work is complex though because the technicians would have to enter a manhole at the bottom of the tank and then climb up into the tank to reach the sensors. Maybe I shouldn't be saying it isn't difficult but they've replaced those sensors before.
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#246
by
psloss
on 09 Dec, 2007 12:14
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dabella - 9/12/2007 8:11 AM
How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
That's the thing -- the history of this says that the sensors themselves aren't necessarily suspect. They've never been able to isolate a location within the whole circuit from the sensor in the tank to the electronics box that processes the signal inside the orbiter aft compartment.
They replaced the LH2 sensors on the STS-115 tank, and one of the circuits STILL failed wet on the 1st tanking.
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#247
by
Ford Mustang
on 09 Dec, 2007 12:15
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Doug Lyons now talking to PAO. I'm recording this.
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#248
by
Ford Mustang
on 09 Dec, 2007 12:17
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All 4 sensors went DRY by SIM command, for about two or three minutes. Then #3 failed, and went back to WET.
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#249
by
Ford Mustang
on 09 Dec, 2007 12:20
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PAO: Where do you think we go after today?
Lyons: MMT meeting at 9 AM, trying to decide where to go. Multiple paths going into MMT, will try to decide which way to go, to implement as soon as possible.
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#250
by
ShuttleDiscovery
on 09 Dec, 2007 12:21
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Coverage ended
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#251
by
shuttlefan
on 09 Dec, 2007 12:22
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Sounds like they'll hold at 5% in the LH2 tank for about 4 hours to troubleshoot, did I pick that up correctly?
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#252
by
dabella
on 09 Dec, 2007 12:25
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Well, if this is a complex problem that is repeating over time and is a security issue and the root cause is unknown, imho, its a good idea to pause the program until a fix or a replacement to the system is found...
it will take time, but its the safest way to go i think..
Dan.-
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#253
by
haywoodfloyd
on 09 Dec, 2007 12:25
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Sounds like they'll have to throw the full resources of NASA at this one.
They can't have this little niggly problem plagueing the rest of the remaining flights.
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#254
by
Targeteer
on 09 Dec, 2007 12:27
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#255
by
on 09 Dec, 2007 12:28
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Do yall think the MMT will decide to roll her back and fix the problem?
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#256
by
Chris Bergin
on 09 Dec, 2007 12:30
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Engineers checking the status of the LOX ECO Number 3 issue, regarding if it's a SIM failure (bad) or a "PSB dry transition range" <--not sure if that's still as bad, but they are looking at it. Hopefully it's not a straight out fail, but I don't know more than what I'm getting.
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#257
by
psloss
on 09 Dec, 2007 12:31
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dabella - 9/12/2007 8:25 AM
Well, if this is a complex problem that is repeating over time and is a security issue and the root cause is unknown, imho, its a good idea to pause the program until a fix or a replacement to the system is found...
The failures in the past have only occurred during a full tanking and even then have been intermittent. So in the past they have been unable to reproduce the problem. This is the first time a sensor circuit has failed WET on successive tanking cycles. And how it behaves during detanking today is TBD. (The "detankings" in the past "second tankings" have been "flight drains" and I believe the circuits continued to behave as predicted in-flight.)
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#258
by
Chris Bergin
on 09 Dec, 2007 12:32
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Justin Wheat - 9/12/2007 1:28 PM
Do yall think the MMT will decide to roll her back and fix the problem?
We do not know at this stage. Let's please keep the chatter down to a minimum, as we're trying to provide live updates.
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#259
by
ETEE
on 09 Dec, 2007 12:33
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If they roll back for repairs which High Bay will the stack end up in?