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A330 ZFW/ZFCG DISAGREE

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A330 ZFW/ZFCG DISAGREE

Old 12th Jan 2013, 17:50
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A330 ZFW/ZFCG DISAGREE

Could someone enlighten me, what this ECAM message means?
Ok, FCOM says: "One FCMC detects that the ZFW or ZFCG data from FMGEC 1 and FMGEC 2 disagree". Still doesn't make much sense to me. Disagree with what?

Last edited by Romasik; 12th Jan 2013 at 17:51.
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Old 13th Jan 2013, 04:44
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In 320 FM1/FM2 GW message on scratchpad in mcdu means 2 tons of weight difference between onside ans offside fmgc..may be same sort for 330.
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Old 13th Jan 2013, 10:07
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it's a daily business, just check the ZFW and CG reinsert it and move on. If it comes up again simply clear it.
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Old 13th Jan 2013, 10:35
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Well, we clear it, we reinsert it - no problem But, the question remains: what data does the FCMC compare with inserted data? How does the aicraft know what is right or wrong???
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Old 13th Jan 2013, 11:06
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Jesus it's an Airbus so who knows what it's thinking or doing.

Try cycling the Left Landing light, that usually fixes most problems on the Bus!!

Who knows what is connected to what in this thing.

Seriously we see this message a lot after entering the MACZFW/ZFW when we get the loadsheet and the data is always checked ok twice to make sure of no finger trouble....

So who knows........

Last edited by nitpicker330; 13th Jan 2013 at 11:09.
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Old 13th Jan 2013, 11:09
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isn't it the MACZFW and ZFW?
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Old 13th Jan 2013, 11:10
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Yes sorry, on holidays and far away from work!! Brain slip
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Old 13th Jan 2013, 12:04
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Planned ZFW

Have you already entered a "planned" ZFW ? If so , i think it is just questioning why you have changed this again as you enter the actual value from the loadsheet.
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Old 13th Jan 2013, 12:10
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Originally Posted by Romasik
"One FCMC detects that the ZFW or ZFCG data from FMGEC 1 and FMGEC 2 disagree".
Still doesn't make much sense to me. Disagree with what?
With each other.
Confirm that the ZFW and ZFCG values from each FMGC are the same as the loadsheet value.
Maybe the figures inserted through one MCDU are different from the one previously inserted through the other unit.
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Old 13th Jan 2013, 12:14
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BTW, today we gave it a try: entered completely crazy CG data (30% instead of 21% from the loadsheet) and DIDN'T GET ANY MESSAGE... And the stab trim set itself based on that figure from the moon...
So, it doesn't protect from the crew entry mistakes. What the hell is the meaning and the purpose???

Last edited by Romasik; 3rd Feb 2013 at 18:15.
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Old 13th Jan 2013, 12:18
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With each other.
Confirm that the ZFW and ZFCG values from each FMGC are the same as the loadsheet value.
Maybe the figures inserted through one MCDU are different from the one previously inserted through the other unit.

We only insert it in one MCDU and sometimes get the message...
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Old 13th Jan 2013, 12:21
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mutley320

Have you already entered a "planned" ZFW ? If so , i think it is just questioning why you have changed this again as you enter the actual value from the loadsheet.

Nope. We don't enter anything in advance. Only the actual data from the loadsheet.
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Old 13th Jan 2013, 13:11
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Did you notice if the message is showing after you inserted the fuel figure but the fuel is not yet on board ?
I understand you have the on ground auto trim setup option, would you have an option for the aircraft to estimate its CG through the landing gear ?
I believe the best option would be to directly question Airbus through your management. This is a very interesting question.

Last edited by CONF iture; 13th Jan 2013 at 13:12.
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Old 13th Jan 2013, 15:13
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Did you notice if the message is showing after you inserted the fuel figure but the fuel is not yet on board ?
I understand you have the on ground auto trim setup option, would you have an option for the aircraft to estimate its CG through the landing gear ?
I believe the best option would be to directly question Airbus through your management. This is a very interesting question.

The fuel is done, ready to go, inserting ZFW/ZFWCG and sometimes getting the message, sometimes not. Today absolutely wild CG didn't trigger any message... and the stab trim set itself automatically accordingly that wild entry.
Looks like there is nothing there to measure the actual CG. We only enter the starting point and then the FCMC calculates CG change with fuel movement and carries on the initial entry mistake, if any. But the ECAM message and its explanation in the FCOM are totally confusing and don't fall in line with my understanding of the system.

Last edited by Romasik; 18th Feb 2013 at 15:06.
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Old 13th Jan 2013, 17:07
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Unfortunately it's easier to get the answer on the forum rather then through management
I see and it is a pity. Airbus will not consider a pilot's question, but they have to reply to a chief pilot. We can get very reliable information on a forum but the manufacturer is the only one to exactly know what is in the beast.
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Old 14th Jan 2013, 09:21
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It is just a communication error between computers... On the ground the pilots are the source of ZFW + ZFWCG information for FMGEC's and therefore the FCMC's, which send the GW values back to FMGEC....so it is important to cross check the correct value each side.
Once airborne the FE portion of the FMGEC does some smart calculations to cross check the GW values and warns you if there is an error.

These glitches happen - the important question is what should you check?
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Old 14th Jan 2013, 11:52
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Interesting stuff.

I've only seen this after I've done a manual loadsheet on an A330, and got the ZFW index and %MAC figures slightly wrong or misread them in the badly lit cockpit, and which would have led to an incorrect THS setting for T/O.

However, the very senior training captain I was with once when it happened, didn't know what it meant !!
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Old 15th Jan 2013, 00:15
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ZFW/ZFCG DISAGREE

the important question is what should you check?


Check the 'Abnormal and emergency procedures' ATA 28 section in FCOM

it says:

"Confirm that the ZFW and ZFCG values from each FMGC are the same as the loadsheet value."
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Old 15th Jan 2013, 04:46
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Strange as only some of our new A330's give this message.

Our SOP is to insert 25/ZFW and Block Fuel as we setup the Perf initially from the Flight Plan.

Then later with the loadsheet we enter the actual data into the PF's and the PM checks his CDU at the same time as we move through final setup.

The message then pops up instantly the data is inserted even though both screens show the same figures???

I've never seen an error.

Last edited by nitpicker330; 15th Jan 2013 at 04:47.
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Old 15th Jan 2013, 09:05
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ZFW/ZFCG DISAGREE

The entered values are used for GW/GWCG calculation by FMGEC and FCMC.

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)

Now if there is any difference between the ZFW/ZFCG values in FCMC and FMGEC (No W&B system fitted),
this message will be triggerd to check and confirm by reentering the values.

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