B-747-400 Fuel Info
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Baby steps please, I could post a bible on this.
Well, I could explain it to you! It may take me several years to type the post though! What in particular would you like to know? PM me and I may be able to forward some info in your direction.
As a starter:-
As a starter:-
Overview
The Fuel System includes nine subsystems which control all fuel
related functions of the Airplane.
related functions of the Airplane.
Fuel Storage Tanks
The Aircraft structure is used to store fuel. Construction features
include tank access, venting and sump drain valve installations.
include tank access, venting and sump drain valve installations.
Fuel Quantity Indication
Fuel quantity indication covers the Electronic System and
components used to measure, monitor, display and activate various
controls used during ground servicing or in-flight management of the
Fuel System. The manual method of determining the Aircraft fuel
load is also described in this subsystem.
components used to measure, monitor, display and activate various
controls used during ground servicing or in-flight management of the
Fuel System. The manual method of determining the Aircraft fuel
load is also described in this subsystem.
Fuelling
Fuelling includes pressure fuelling control and operation as well as
manual (overwing) fuelling.
manual (overwing) fuelling.
Engine Feed
This section includes the Fuel Supply System for Engine operation.
Also covered are System interconnections for operations such as
crossfeed, jettison and defuelling.
Also covered are System interconnections for operations such as
crossfeed, jettison and defuelling.
APU Feed
APU feed covers the APU Fuel Supply System, components and
operation.
operation.
Reserve to Main Tank Transfer
This subsystem covers the components required to transfer fuel from
the Reserve to the Main Wing Tanks.
the Reserve to the Main Wing Tanks.
Horizontal Stabilizer Fuel Transfer
This subsystem covers the components needed to fuel, transfer and
jettison fuel from the Horizontal Stabilizer Fuel Tank.
jettison fuel from the Horizontal Stabilizer Fuel Tank.
Scavenge
The Scavenge System equipment is installed to convert residual fuel
into usable fuel.
into usable fuel.
Jettison
Jettison is the in-flight system used for Aircraft rapid weight
reduction. Alternate jettison functions include fuel transfer, Engine
feed and defuelling.
reduction. Alternate jettison functions include fuel transfer, Engine
feed and defuelling.
Join Date: Oct 2006
Location: Sydney, Australia
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Try page six of this link;
http://www.aaib.dft.gov.uk/cms_resou...LG%2006-06.pdf
It has a simple schematic of the fuel feed system of the B744.
http://www.aaib.dft.gov.uk/cms_resou...LG%2006-06.pdf
It has a simple schematic of the fuel feed system of the B744.
Join Date: Feb 2004
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The CBT programs I've used also show fuel coming straight out of the HST.
Regards.
NSEU
Last edited by NSEU; 16th Nov 2006 at 06:25. Reason: Edited for clarity
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I was reading the question as can you dump directly from the HST, i.e. is it selectable.
Strictly speaking as NSEU states the fuel from the HST doesn't go to the CTR tank it connects directly to the refuel/jettison manifold.
However you can't directly dump just the HST which is how I saw the question, I was wrong in saying that it goes to the CTR tank, normal fuel transfer from the HST would however in this scenario it wouldn't. Hope that helps.
Strictly speaking as NSEU states the fuel from the HST doesn't go to the CTR tank it connects directly to the refuel/jettison manifold.
However you can't directly dump just the HST which is how I saw the question, I was wrong in saying that it goes to the CTR tank, normal fuel transfer from the HST would however in this scenario it wouldn't. Hope that helps.
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I'm wondering what would happen if you activated the jettison system and switched off your O/J pumps (inboard tanks and CWT) for a short period.... Would you selectively dump fuel from the HST?
Regards.
NSEU
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No. Simply because once a jettison is initiated a control relay is energised thereby activating the O/J pumps. You have to remember this is a "2 man crew", no flight engineer to organise and concentrate on such operations. Once the jettison is initiated the crew would dial in a "fuel to remain" figure which will then be the point at which the jettison ceases. If the O/J pumps are not allready selected on, then they will be comanded to on.
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No. Simply because once a jettison is initiated a control relay is energised thereby activating the O/J pumps. You have to remember this is a "2 man crew", no flight engineer to organise and concentrate on such operations. Once the jettison is initiated the crew would dial in a "fuel to remain" figure which will then be the point at which the jettison ceases. If the O/J pumps are not allready selected on, then they will be comanded to on.
Perhaps you were thinking of another aircraft type? 767?
(Edit) Despite the absence of an F/E, we can assume that the pumps will be in a normal configuation for the fuel on board (i.e. all pumps manually selected on in tanks with fuel in them). EICAS messages will advise the crew to take action if the tanks become empty.
Regards.
NSEU
Last edited by NSEU; 17th Nov 2006 at 01:36. Reason: additional text
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Looking at CBT's, wiring schematics and the description of pump operation in training notes, yes, it is possible to jettison fuel from the HST only (if you deselect the CWT and wing O/J pumps).
Why you would want to only do this is another matter
Regards.
NSEU
Why you would want to only do this is another matter
Regards.
NSEU
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NSEU you are quite correct, my bad, as you say though why would you do it? If you wanted to xfer gas from the HST into wing tanks quick sticks during maint, you could pull the nozzle cb's or pull the cannon plugs off the jet nozzles and set the system up as you described. Then just open refuel valves for tank to recieve fuel. Certainly though it would be not normal for crew to be doing such things.
