A330 ZFW/ZFCG DISAGREE
Just out of interest, A33Zab, where does that diagram come from?
Thanks.....
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@CONF iture:
Not that I'm aware off,
however there is a connection on LGCIUs reserved for optional W&B.
Freighter and/or MRTT ??
however there is a connection on LGCIUs reserved for optional W&B.
Freighter and/or MRTT ??
Last edited by A33Zab; 15th Jan 2013 at 11:05.
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A33Zab:
Nice diagramm, but it's not answering the post question. FCMC takes over CG calculation only after initial ZFCG and ZFW entered by pilots. It does't have anything to compare these values with (unless aicraft if fitted with weight and balance system).
Also I can't see why data in two FMGSs could be different. They are cyncronized and once your enter numbers in one of them they immediatelly pop up in the other one.
Today we did it again: this time entered ZFW and ZFWCG well outside aircraft limitations. And - no effect. Not a single message! How nice for such an advanced aircraft...
Nice diagramm, but it's not answering the post question. FCMC takes over CG calculation only after initial ZFCG and ZFW entered by pilots. It does't have anything to compare these values with (unless aicraft if fitted with weight and balance system).
Also I can't see why data in two FMGSs could be different. They are cyncronized and once your enter numbers in one of them they immediatelly pop up in the other one.
Today we did it again: this time entered ZFW and ZFWCG well outside aircraft limitations. And - no effect. Not a single message! How nice for such an advanced aircraft...
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Reset of ZFW/ZFWCG disagree
I've had this message several times on A330 and found that a reset of the FCMC's has always fixed the problem.
You've got a 50/50 chance of getting the correct one the first time.
Usually as soon as the reset button for the offending FCMC is pulled the message will clear.
You've got a 50/50 chance of getting the correct one the first time.
Usually as soon as the reset button for the offending FCMC is pulled the message will clear.
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It's for cross-checking the data that ends up in the FMGECs against each other. It's not for checking the entered data against max/min values or anything else along those lines - it is an internal comparison only.
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It's for cross-checking the data that ends up in the FMGECs against each other. It's not for checking the entered data against max/min values or anything else along those lines - it is an internal comparison only.
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Romasik
That is not necessarily the case. The error could be at the FCMC end, or the data may not have been sent correctly, or got lost on the way.....
Just re-enter the ZFW + CG, or reset the FCMC's and then re-enter the data.
Also I can't see why data in two FMGSs could be different
Just re-enter the ZFW + CG, or reset the FCMC's and then re-enter the data.
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This message comes too often to be a failure. And, BTW, there is a NORMAL SOP for that case:
"‐ Check the loadsheet CG, against the ECAM CG. In case there is a discrepancy of more than 2 %, check that the ZFW and the ZFWCG have been correctly inserted in the MCDU, then rely on the ECAM CG. If the difference is less than 2 %, no further action is required. Rely on the ECAM CG."
Once again, it says to check that the ZFW and ZFWCG are correctly inserted, which is totally irrelevant. As I already said, you may enter complete BS outside the aircraft limitations and in most cases get no message. So, the original post question remains open...
"‐ Check the loadsheet CG, against the ECAM CG. In case there is a discrepancy of more than 2 %, check that the ZFW and the ZFWCG have been correctly inserted in the MCDU, then rely on the ECAM CG. If the difference is less than 2 %, no further action is required. Rely on the ECAM CG."
Once again, it says to check that the ZFW and ZFWCG are correctly inserted, which is totally irrelevant. As I already said, you may enter complete BS outside the aircraft limitations and in most cases get no message. So, the original post question remains open...
Last edited by Romasik; 16th Jan 2013 at 11:14.
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My last attempt....
Each FCMC receives ZFW and ZFWCG from both FMGEC 1+2 - two independent values which should be the same.
Each FCMC compares the values it receives from FMGEC 1 with the values it received from FMGEC 2
If a FCMC detects a disagreement between the values it has been sent, it gives you an ECAM message.
IT HAS NOTHING TO DO WITH LIMITATIONS.......OR BS VALUES.
please excuse the shouting.....
Each FCMC receives ZFW and ZFWCG from both FMGEC 1+2 - two independent values which should be the same.
Each FCMC compares the values it receives from FMGEC 1 with the values it received from FMGEC 2
If a FCMC detects a disagreement between the values it has been sent, it gives you an ECAM message.
IT HAS NOTHING TO DO WITH LIMITATIONS.......OR BS VALUES.
please excuse the shouting.....
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TyroPicard:
Still I don't see any sense. The data entered into each FMGEC is identical. Why should it in turn supply FCMC with different data and not once in a while but quite often? What kind of processing is going on with a simple entry of CG and ZWF? It's just what it is and doesn't require any processing. As long as aircraft by itself is not capable of calculating the actual CG and weight, all calculations around the initial pilot data entry are useless.
Still I don't see any sense. The data entered into each FMGEC is identical. Why should it in turn supply FCMC with different data and not once in a while but quite often? What kind of processing is going on with a simple entry of CG and ZWF? It's just what it is and doesn't require any processing. As long as aircraft by itself is not capable of calculating the actual CG and weight, all calculations around the initial pilot data entry are useless.
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all calculations around the initial pilot data entry are useless.
- FG and FCPC control laws affected.
- Vs1g speed calculation affected.
- Wrong TO THS setting.
- FM predictions and speeds affected.
- PFD characteristic speed accuracy affected.
- Optimum CG control by FCMC affected.
- SD permanent data GW/GWCG unaccurate.
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A33Zab:
Come on!
I mean, there is nothing that any aircraft computer can do to alter initial pilot entry of ZFW/ZFWCG. Whatever you enter, even complete BS - will be used as a starting point for data processing. And I don't see any reason why this starting point would become different in FMGEC1 and FMGEC2.
Come on!
I mean, there is nothing that any aircraft computer can do to alter initial pilot entry of ZFW/ZFWCG. Whatever you enter, even complete BS - will be used as a starting point for data processing. And I don't see any reason why this starting point would become different in FMGEC1 and FMGEC2.
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ZFW ZFCG DISAGREE
Disagreement between pilot entered values and FCMC values
Disagreement between pilot entered values and FCMC values
In my opinion, since zfw can only be pilot entered but fuel quantity can also be FCMC sensed, a difference between pilot entered FOB and or ZFW/ZFCG in INIT B page can lead to a difference between GW/GWCG calculated by FCMC and FMC. However the caution refers to ZF values which are obviously independent of fuel and can only be pilot entered...
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Microburst2002:
I also see only fuel traces in this story. In particular the message often comes when there was no fuel taken on turnaround, i.e. fuel distribution may be not standard.
I also see only fuel traces in this story. In particular the message often comes when there was no fuel taken on turnaround, i.e. fuel distribution may be not standard.
Last edited by Romasik; 17th Jan 2013 at 18:17.
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The FCMC calculations are used for CG control and is the primary source for
FM and FG.
The FMGEC values is the backup source for FM, FG and is primarly
used for AFT CG monitoring.
(as watchdog for FCMC CG control)
I remember coming across this a long, long time ago. If memory serves me right, isn’t it the case that the FCMC used the pilot-entered ZFWCG and calculates the GWCG by taking the actual fuel mass/distribution onboard on a per-tank basis, whereas the FMGC used the pilot-entered ZFWCG and calculates the GWCG by assuming a standard fuel distribution for any given FOB? A non-standard fuel distribution would, of course, result in a different fuel CG effect and hence, a difference between the GWCG outputs from the FCMC and FMGC.
Also, had you already entered a BLOCK figure in INIT B when the message appeared?