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HAWK21M
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B752 Fqis Query.

Wed Dec 17, 2008 1:05 am

Anyone experienced a situation when Fuel is transferred from Ctr tank to Wing tanks in a B752 on Ground,approx 200kgs disappears/does not get registered?

regds
MEL.
I may not win often, but I damn well never lose!!! ;)
 
boeing767mech
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RE: B752 Fqis Query.

Wed Dec 17, 2008 1:55 am



Quoting HAWK21M (Thread starter):
Anyone experienced a situation when Fuel is transferred from Ctr tank to Wing tanks in a B752 on Ground,approx 200kgs disappears/does not get registered?

It's in the fueling manifold or you have a bad Fuel Quanity Processor. Try chapter 28 in the FIM.

David
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fadecfault
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RE: B752 Fqis Query.

Wed Dec 17, 2008 12:54 pm

Normal I'd say from my observations during 757 and 737 fuel transfer. It's probably in the manifolds as said above.
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HAWK21M
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RE: B752 Fqis Query.

Wed Dec 17, 2008 2:32 pm



Quoting Boeing767mech (Reply 1):
It's in the fueling manifold

How much capacity would the entire manifold hold approx?
regds
MEL.
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boeing767mech
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RE: B752 Fqis Query.

Wed Dec 17, 2008 3:20 pm



Quoting HAWK21M (Reply 3):
How much capacity would the entire manifold hold approx?

Don't know what does the MM say???


David
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Tristarsteve
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RE: B752 Fqis Query.

Wed Dec 17, 2008 5:55 pm

I transfer fuel every week on an A319. The total on board goes down when you start, but when you have finished it recovers to the same total.
The refuel manifold holds around 200kg of fuel, but when it is unpressurised there are two drain valves and the fuel drains out into each wing tank (when there is space).
 
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HAWK21M
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RE: B752 Fqis Query.

Wed Dec 17, 2008 8:41 pm



Quoting Boeing767mech (Reply 4):
Don't know what does the MM say???

The AMM does not list the total capacity of the manifold.

Quoting TristarSteve (Reply 5):
The refuel manifold holds around 200kg of fuel, but when it is unpressurised there are two drain valves and the fuel drains out into each wing tank (when there is space).

Similiar to the B752,hence the readings should reappear,which does not even after 45mins.I'm suspecting sticking manifold drain valves.
regds
MEL
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Mender
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RE: B752 Fqis Query.

Thu Dec 18, 2008 9:34 am

1 - The fuel manifold drains into the centre tank on the 757 not the wing tanks (Steve was referring to the Airbus)

2 - The fuel in the manifold has not be seen by FQIS therefore is irrelevant. FQIS can only see fuel once it is in the tanks.

Are you saying that you are re-fuelling the main tanks less than full and that the fuel level is dropping in the centre tank and the quantity in the main tanks is increasing and the total fuel on board is staying the same?

Also, are you saying that this only happens to one aircraft in your fleet and it doesn't happen to any other aircraft in your fleet?

If there is only a small quantity of fuel required in the centre tank it is difficult to accurate measure because of the area that it covers.
 
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HAWK21M
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RE: B752 Fqis Query.

Fri Dec 19, 2008 12:39 pm



Quoting Mender (Reply 7):
Are you saying that you are re-fuelling the main tanks less than full and that the fuel level is dropping in the centre tank and the quantity in the main tanks is increasing and the total fuel on board is staying the same?

No.In case the Fuel at Departure is less than 13200 kgs...Center tank fuel if present eg 600kgs is transferred to the wing tank,but only 400kgs gets transferred to the wing tanks & the Ctr tank reads NIL,but the 200kg difference in totaliser exists from the reading prior to transferring.

Quoting Mender (Reply 7):
Also, are you saying that this only happens to one aircraft in your fleet and it doesn't happen to any other aircraft in your fleet?

True.

regds
MEL
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Mender
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RE: B752 Fqis Query.

Sun Dec 21, 2008 11:02 pm



Quoting Mender (Reply 7):
1 - The fuel manifold drains into the centre tank on the 757 not the wing tanks (Steve was referring to the Airbus)

2 - The fuel in the manifold has not be seen by FQIS therefore is irrelevant. FQIS can only see fuel once it is in the tanks.



Quoting HAWK21M (Reply 8):
No.In case the Fuel at Departure is less than 13200 kgs...Center tank fuel if present eg 600kgs is transferred to the wing tank,but only 400kgs gets transferred to the wing tanks & the Ctr tank reads NIL,but the 200kg difference in totaliser exists from the reading prior to transferring.

You really shouldn't de-fuel the centre tank below 500 kgs so this is still not clear to me yet but i thought you was saying that you was loosing the fuel from the centre tank during re-fuel, not transfer hence the quotes above.

In our airline we refuel 6500 per wing and the rest in the centre so I don't understand the loads above. However if the load was 13200 we'd put 6600 per wing.

I don't think there is anything wrong with this aircraft from what you've described.
 
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HAWK21M
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RE: B752 Fqis Query.

Mon Dec 22, 2008 7:43 am



Quoting Mender (Reply 9):
You really shouldn't de-fuel the centre tank below 500 kgs

We operate freighters....If the next sector needs <13200kgs fuel....& there was fuel in the CTR tank from the previous sector,this would be unusable & a weight penalty,hence it is transferred to the wing tanks.

Quoting Mender (Reply 9):
In our airline we refuel 6500 per wing and the rest in the centre so I don't understand the loads above. However if the load was 13200 we'd put 6600 per wing.

Same here.

Quoting Mender (Reply 9):
I don't think there is anything wrong with this aircraft from what you've described.

Guess I may not be conveying it clearly.
I'll rephrase.....Aircraft departed from previous sector with 17,000kgs [LH 6500,CTR 4000,RH 6500].
On Arrival presume there is 7300kgs [LH3500kgs,CTR 300,RH3500kgs].
Now next sector fuel at departure required is 13,000kgs[LH 6500,CTR nil,RH6500]....But there is still 300kgs in the CTR tank which is moved to the wing tanks,but while the CTR tank gets Empty during transferring vide defuelling valves,it shifts only 100kgs in the Wing tank & 200kgs is not accounted for.

Trust its clear now.

regds
MEL
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Tristarsteve
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RE: B752 Fqis Query.

Mon Dec 22, 2008 10:32 am

I personally think that all you have is centre tank gauge problem. Well not a problem that can be solved.
The centre tank has a large flat floor and 200kg of fuel is a very thin layer spread over the floor. Depending on the aircraft attitude this fuel is measured or not.
You know how difficult it is to fuel a centre tank with only say 500kg. You pump in 800litres and the gauges read nothing, then suddenly they read too much. Luckily nowadays most aircraft have a minimum fuel in the centre tank so we don't see this problem so often.
 
boeing767mech
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RE: B752 Fqis Query.

Mon Dec 22, 2008 3:28 pm

Next time your airplane is at your station, if you have time. Pump the center tank dry and do a dry cap check using the Fuel Qty Processor. It states in the FIM you can do this if you have a honeywell system installed. When we have problems with fuel qty I have found this is the fastest way to troubleshoot a problem without draining the airplane of fuel, as long as you have time. But as always read the MM and FIM depending on your airplanes, then may not be set up as my airplanes. I know some airplanes have simmons fuel qty processors and some have honeywell. So you can always do the same things between the two systems.

David
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tdscanuck
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RE: B752 Fqis Query.

Mon Dec 22, 2008 6:11 pm



Quoting HAWK21M (Reply 10):
On Arrival presume there is 7300kgs [LH3500kgs,CTR 300,RH3500kgs].
Now next sector fuel at departure required is 13,000kgs[LH 6500,CTR nil,RH6500]....But there is still 300kgs in the CTR tank which is moved to the wing tanks,but while the CTR tank gets Empty during transferring vide defuelling valves,it shifts only 100kgs in the Wing tank & 200kgs is not accounted for.

Are you calling center tank empty as FQIS = 0 or when the center pump goes low pressure?

The FQIS biases downward as it approaches zero to meet the FAR requirement that the FQIS never show fuel when there isn't any...as a result, it hits zero when it's not actually empty (by a couple of hundred pounds). So if you're just moving fuel until the FQIS says zero, then it sounds like it's doing exactly what it's supposed to do.

Tom.
 
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HAWK21M
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RE: B752 Fqis Query.

Tue Dec 23, 2008 3:43 pm



Quoting Tdscanuck (Reply 13):
Are you calling center tank empty as FQIS = 0 or when the center pump goes low pressure?

Yes.The former.

Quoting Boeing767mech (Reply 12):
if you have time.

Tough at Line,but def work on it at the next major check.
regds
MEL
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boeing767mech
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RE: B752 Fqis Query.

Tue Dec 23, 2008 4:56 pm



Quoting HAWK21M (Reply 14):
Tough at Line,but def work on it at the next major check.

Takes about 30 minutes to troubleshoot if you have a dry tank.

David
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tdscanuck
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RE: B752 Fqis Query.

Tue Dec 23, 2008 7:14 pm



Quoting HAWK21M (Reply 14):
Quoting Tdscanuck (Reply 13):
Are you calling center tank empty as FQIS = 0 or when the center pump goes low pressure?

Yes.The former.

That's probably what's getting you...the FQIS is tuned to show zero when there's actually usable fuel left. If you kept transferring until the center pump went low pressure the FQIS would still show zero but you should be able to recover most of the missing fuel.

Tom.
 
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HAWK21M
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RE: B752 Fqis Query.

Sun Feb 22, 2009 10:49 am



Quoting Tdscanuck (Reply 16):
That's probably what's getting you...the FQIS is tuned to show zero when there's actually usable fuel left. If you kept transferring until the center pump went low pressure the FQIS would still show zero but you should be able to recover most of the missing fuel.

Your Explanation makes sense,I guess thats exactly whats occuring.
regds
MEL
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