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skywalker92
Topic Author
Posts: 62
Joined: Thu Aug 06, 2015 8:45 am

Engine driven fuel pumps

Fri May 12, 2017 12:14 pm

Hello avgeeks,
I got a problem when going through some articles about aircraft fuel systems and how fuel is fed to the engine. Already I know that there are booster pumps in wing fuel tanks and center tanks to supply fuel to the engine driven fuel pump with a head pressure. My question is what will happen if we loose the engine driven fuel pump? Will the engine keeps on running with the aid of booster pumps or will it flame out?

Thanks,
Skywalker
 
thepinkmachine
Posts: 464
Joined: Tue Apr 28, 2015 4:43 pm

Re: Engine driven fuel pumps

Fri May 12, 2017 1:23 pm

I doubt it would, as the engine driven pump creates the high pressure for the fuel injectors.

Never heard of the engine pump failing, though...
 
Woodreau
Posts: 2154
Joined: Mon Sep 24, 2001 6:44 am

Re: Engine driven fuel pumps

Fri May 12, 2017 1:29 pm

The engine flames out if the engine driven fuel pumps don't work.

At least on the V2500 and PW1000 engines, there is a LP fuel pump and a HP fuel pump separate from the fuel pump in the wing tanks.
 
StereoTechque
Posts: 201
Joined: Sat Nov 28, 2015 7:24 am

Re: Engine driven fuel pumps

Fri May 12, 2017 1:50 pm

Very remote chances of an Engine fuel pump failing, but if it does happen definitely the engine flames out.
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

Re: Engine driven fuel pumps

Sat May 13, 2017 3:05 am

If nothing else every engine has multiple pumps. On the 330 and 350, each engine has two main pumps and a backup pump. The chance of losing all three to pump faults is very remote.

There are, however, rare cases where the engines are just gravity fed, for example on the 330 when on emergency power on approach. AFAIK the engines will not flame out.
 
StereoTechque
Posts: 201
Joined: Sat Nov 28, 2015 7:24 am

Re: Engine driven fuel pumps

Sat May 13, 2017 3:23 am

Starlionblue wrote:

There are, however, rare cases where the engines are just gravity fed, for example on the 330 when on emergency power on approach. AFAIK the engines will not flame out.

That you are referring to is Aircraft fuel pump. If the wing aircraft fuel pump on the A320 fails, engine can be gravity fed. But if the Engine Fuel Pump fails, the engine should flame out.
 
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Starlionblue
Posts: 20801
Joined: Fri Feb 27, 2004 9:54 pm

Re: Engine driven fuel pumps

Sat May 13, 2017 3:55 am

StereoTechque wrote:
Starlionblue wrote:

There are, however, rare cases where the engines are just gravity fed, for example on the 330 when on emergency power on approach. AFAIK the engines will not flame out.

That you are referring to is Aircraft fuel pump. If the wing aircraft fuel pump on the A320 fails, engine can be gravity fed. But if the Engine Fuel Pump fails, the engine should flame out.


Fair dinkum. This is true.

We do have two engines though. :D
 
Apprentice
Posts: 778
Joined: Sat Jan 19, 2013 12:51 pm

Re: Engine driven fuel pumps

Sat May 13, 2017 4:23 am

Hi:
If Engine's Pump fail, a/c Pump is not able to provide enough fuel pressure/ flow. Engine will shut down.
If a/c pumps fail, engine's pumps are designed to keep engine running in this condition. A/c should descend bellow 8000mt to avoid cavitation on engine pump's inlet. Below that altitude, engine fuel system will work flawlessly
For a/c Pumps fail situation, we are talking about all electric pumps off (like electric failure). In most of the planes, 1 electric booster pump should provide enough fuel flow to both engines (using cross feed).
Even a APU DC Pump should be connected in a way to be capable to supply one engine, again below a/c ceiling

Rgds
 
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RotateAero
Posts: 15
Joined: Sat Oct 08, 2016 1:12 am

Re: Engine driven fuel pumps

Sat May 13, 2017 4:27 am

The engine will flame out if the engine driven pump fails. Fuel nozzle pressure is quite high to achieve the vaporization needed in the burner cans.

Also, The VSV's (Variable Stator Vanes) are driven by fuel pressure. If the vanes are inop, engine control is degraded.

At the bottom of this page http://rotate.aero/forum/cf680c2-76/103-ata-76-12-ge-cf6-80c2a5f-engine-fuel-solenoid#118 is a picture of a fuel solenoid. Those mesh holes are extremely small. It takes a heck of a lot of pressure to push enough fuel through those to keep a 50K+ thrust engine running.
 
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Horstroad
Posts: 595
Joined: Thu Apr 08, 2010 8:19 pm

Re: Engine driven fuel pumps

Sat May 13, 2017 7:42 am

Apprentice wrote:
If a/c pumps fail, engine's pumps are designed to keep engine running in this condition.
For a/c Pumps fail situation, we are talking about all electric pumps off (like electric failure).

The MD11 is the special snowflake again. Because eng #2 is located so high above the fuel tanks, it can't be fed by gravity (or suction) alone. Thats why two of the 18 fuel pumps are powered by a emergency ac bus and can not be dispatched via MEL. If they fail they have to be replaced or swapped before the next flight.
One of them feeds fuel from tank #2 to eng #2 to keep the engine running, the other one feeds fuel from the tail tank to eng #2 because you don't want to land with 6t of fuel trapped in the horizontal stabilizer.
 
Apprentice
Posts: 778
Joined: Sat Jan 19, 2013 12:51 pm

Re: Engine driven fuel pumps

Sat May 13, 2017 11:56 am

Horstroad, hi:
You are right, I just forget MD11.
DC10-30 is similar, which 1ea Pump No-Go, out of memory, feed by LH AC Emergency Bus.
This I should not forget. In one departure it became inop and we use a Pump from Upper Auxiliary tank to dispatch a/c.
With a/c fueled for flight, mechanism that allows R/R pumps w/o refueling did not work for this Tank 2's fuel pump and we note that when tried to remove the Pump.
Pumps were swapped, a/c departed with deferred Pump's isolation mechanism, and I had to take a long shower.l
Rgds.
 
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skywalker92
Topic Author
Posts: 62
Joined: Thu Aug 06, 2015 8:45 am

Re: Engine driven fuel pumps

Sat May 13, 2017 2:48 pm

thepinkmachine,Woodreau,StereoTechque,Starlionblue,Apprentice,RotateAero and Horstroad thanks for the explanations! :) :)
 
BravoOne
Posts: 4094
Joined: Fri Apr 12, 2013 2:27 pm

Re: Engine driven fuel pumps

Sat May 13, 2017 2:52 pm

StereoTechque wrote:
Starlionblue wrote:

There are, however, rare cases where the engines are just gravity fed, for example on the 330 when on emergency power on approach. AFAIK the engines will not flame out.

That you are referring to is Aircraft fuel pump. If the wing aircraft fuel pump on the A320 fails, engine can be gravity fed. But if the Engine Fuel Pump fails, the engine should flame out.



What I think you meant was suction feed?

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