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Tbur

Fuel Management Best Practices and an unimportand question

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Hi,

 

that's a very impressing model of the Queen. As you sit in the cockpit (virtually of course) it is the feeling of smoothenes in flying as you will have as passenger in this beast. Very great work.

 

Now 2 questions:

 

1) Is there some information available about fuel management best practice. What I mean is e.g. when to close or oben X-fer valves and which one (inner, outer) , when use the override pumps and so on. I tried to get through  the FCOM and QRH. There is a lot of descriptions in the case of imbalance and so on but I've not been able to get out some kind of standard practice. So "instinctively" I managed in a flight from EDDS to OMDB (86 tons fuel total at t/o) to watch when main 2,3 get equal to main 1,4 (reserve reached 0) and then close the outer x-fer valves according to the principle one tank for one engine. I got a warning to switch on the overide pumps which I successfully did. But did I right ? Some hints and help are appreciated.

 

2) In last summer I'd the opportunity to have a session in a CAE Level-D flight simulator 747-400 at the Lufthansa trainig center in Frankfurt as a birthday gift. So I remembered that the landing light switches had been installed turned by 180 degrees that means Up = ON, down = OFF ! Was this an (German) option or is something wrong with my memory.

 

Best regards

 

Thomas Burchard

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1) Is there some information available about fuel management best practice. What I mean is e.g. when to close or oben X-fer valves and which one (inner, outer) , when use the override pumps and so on. I tried to get through  the FCOM and QRH. There is a lot of descriptions in the case of imbalance and so on but I've not been able to get out some kind of standard practice. So "instinctively" I managed in a flight from EDDS to OMDB (86 tons fuel total at t/o) to watch when main 2,3 get equal to main 1,4 (reserve reached 0) and then close the outer x-fer valves according to the principle one tank for one engine. I got a warning to switch on the overide pumps which I successfully did. But did I right ? Some hints and help are appreciated.

 

Burn fuel out of the center body first (center tanks, stab tanks and AUX tanks).

Burn fuel out of the inner mains first (OVRD pumps ON).

Once the inner and outer are equal, turn the OVRD OFF and close the outer (unguarded) XFEEDs (the EICAS will show "FUEL TANK/ENG" when you need to do this).

 

The EICAS will generally yell at you if the plane is misconfigured, as a very, very basic guide.

 

 

 


2) In last summer I'd the opportunity to have a session in a CAE Level-D flight simulator 747-400 at the Lufthansa trainig center in Frankfurt as a birthday gift. So I remembered that the landing light switches had been installed turned by 180 degrees that means Up = ON, down = OFF ! Was this an (German) option or is something wrong with my memory.

 

This is an oddity. Pretty sure DLH is the only one who does this. There may be one or two more, though.

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Hi Kyle,

 

thanks a lot. It seem I did it in this way more less.

 

Thomas Burchard

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Thomas,

 

If you go to the FUEL section of the manual, you will find a description of how to configure the fuel system depending upon your fuel load, and how it should change in flight...

 

There really is no "technique" per se (which implies that pilots might do it differently depending on their own style or desires.  There is ONE way that the system is to be managed and it should be managed that way ALL the time.

 

Otherwise you wind up with lots of issues...  from hydraulic pump overheating to CG problems...

 

Hope that helps!

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Small question. How to deal with fuel imbalance? I know the concept, however i have difference between calculated and totalizer and would like to fix it.

 

Tom Link

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Look at the QRH. 

 

That said, a difference in calculated and totalizer values normally has nothing to do with fuel imbalance, it normally indicates a fuel leak.

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Look at the QRH.

 

That said, a difference in calculated and totalizer values normally has nothing to do with fuel imbalance, it normally indicates a fuel leak.

generally speaking, that is the case. But with everything, like altimetry etc.... there is a tolerance. A small split is tolerable, a big split that increases considerably over time might indicate a leak.

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generally speaking, that is the case. But with everything, like altimetery etc.... there is a tolerance. A small split is tolerable, a big split that increases considerably over time might indicate a leak.

 

I never said there wasn't a tolerance?  :huh:

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a difference in calculated and totalizer values normally indicates a fuel leak.

(My paraphrasing)

 

You didn't say that there was, either.

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(My paraphrasing)

 

You didn't say that there was, either.

 

Which is why I said normally, indicating there may be exceptions. Not really sure what nit picking my posts is adding to the topic.

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Brian,

 

I may be incorrect but I'm not sure your understanding the difference between a Calc/Totalizer Split and fuel imbalance.  A split between Calculated and Totalizer fuel means that the fuel going though the fuel flow transmitters on the engines and being totaled fuel used by the FMC calculator disagrees with the Fuel Qty indication system.  That indeed CAN indicate a fuel leak,  or it could just be a bad fuel flow transmitter.  In regards to fuel imbalance,  you can balance fuel by turning off pumps and opening crossfeeds as necessary to burn fuel out the tanks that are high and to leave fuel in the tanks that are low until they balance. 

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Where can I check the exact fuel load in the tanks?

(I'm still going to through the manual).

 

Tom Link

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Tom, 

 

The Fuel Synoptic shows you the breakdown by tank and pump and crossfeed status on the Lower Eicas

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Which is why I said normally, indicating there may be exceptions. Not really sure what nit picking my posts is adding to the topic.

 

because you gave the impression that the two quantities NORMALLY correlate 100% of the time... they NORMALLY don't on long hauls. Since they don't, there is a tolerance as to how discrepant the 2 different quantities can be before action is required.

 

(The capatilised lettering is just for emphasis. Not yelling.)

 

Brian,

 

I may be incorrect but I'm not sure your understanding the difference between a Calc/Totalizer Split and fuel imbalance. A split between Calculated and Totalizer fuel means that the fuel going though the fuel flow transmitters on the engines and being totaled fuel used by the FMC calculator disagrees with the Fuel Qty indication system. That indeed CAN indicate a fuel leak, or it could just be a bad fuel flow transmitter. In regards to fuel imbalance, you can balance fuel by turning off pumps and opening crossfeeds as necessary to burn fuel out the tanks that are high and to leave fuel in the tanks that are low until they balance.

 

Hi Paul

 

I understand the difference between the two totally independent functions but thank you for the clarification.

 

Regarding Totalizer/FMC Calc - I regularly use these 2 independent quantities to cross check fuel consumption on long hauls whilst filling out my flight plan Nav Log. As I understand it, there were large discrepancies in the 744's early years, but these were corrected with FQIS, FMC and FF transmitter improvements in the years that followed. Without checking, I can't be certain, but am fairly sure they still become discrepant over prolonged flight, but am unsure to what extent. I would expect <700kg (1103 lbs). You would know more than I that fuel indications aren't an exact science on aircraft in practical terms. Of course, they are still very accurate considering.

 

Regarding fuel balance - it isn't rocket science. My mind was blown that the crew of BA 268 (infamous 3 engine, go after EFATO) didn't know how to effectively manage their fuel distribution, in-flight. In my mind, the biggest challenge with fuel balancing is that encountered by Air Transat 236 (opening crossfeeds with a leak in the system).

 

Let me know what you think?

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Hey Brian,

 

OK, so since you understand the differences and where they come from, yes there will be a split between the indications and you are correct in that it varies by aircraft and increases with stage length.  One of the aircraft in our current fleet suffered a 6.8K Split after arriving from a 12.5 trip and that was cause for a logbook write up.  The problem then is trying to find out which of the 4 engine transmitters might be defective.  I'm not exactly certain at what point it becomes alarming vs normal but I know 6K over 12 hrs was excessive with a full fuel load.   From what I see, the crews I worked with were more concerned with Totalizer being on plan and the split was more to monitor for a possible fuel leak scenario.  If your Totalizer fuel is on Plan or above, your probably in good shape and aren't seeing a fuel leak develop.

 

You also correct that fuel balancing isn't rocket science but it is important.  The 747-400 has a tendency to require a bit of balancing from time to time and most of the crews I flew with left the fuel page up on the lwr eicas the entire flight to keep an eye on things before they became problematic.

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