Fuel pumps

[mamo]

Hi
Could someone tell me if the fuel pumps are of any use?
I've noticed that I can always start the engines with all the pumps off.
I even tried to start with only the right tank full of fuel (the left and center empty), crossfeed closed, and both engines always start. That way the left engine should never start.
By the way, I saw in the manual that APU is getting fuel from the left tank, so with this one empty, it should not run.
I've set realism to full.

Am I doing wrong or the fuel switchs on the overhead only fake?
Best regards.

ps: I think there is the same problem with the hydraulic as the ailerons and rudder should not work when all switchs are off (I understand this would be very hard to simulate in FS2002).

[atr_42_500]

>only fake

I've flown about 1 hour with zero fuel on board...
the fuel "low pressure" lights are simulated, though!

http://www.flightsim.com/dcforum/Use...7445ff5667.jpg

[ToddNicholson]

If you've flown with zero fuel you should double-check your realism settings in FS. Make sure that the box "unlimited fuel" is not checked. I ran out of fuel once. Landed with power, turned onto the taxiway at KLAS and she ran out and died.

Todd

[atr_42_500]

:-shy

... oups, I didn't know about that! Thanx, Todd!

http://www.flightsim.com/dcforum/Use...7445ff5667.jpg

[abent]

If you turn the center fuel pumps on it will drain the center tank first. I like to do this. I pretend that I should land with as little fuel as possible in the center tank for structural reasons. I read something about this somewhere. I have no idea if it applies to a 737 or not. Just having fun using my over active imagination!
Take care, Adam

[HartmannH]

[font size="1" color="#FF0000"]LAST EDITED ON Mar-29-02 AT 04:55PM (EDT)[/font][p]Hi,

the 737 has two fuel pumps for each engine: one engine-driven and one electrical. With the fuel pump switches on the overhead, only the electrical pumps (and tank selection) are controlled.

Even during startup (fan rotation driven by bleed air) the engine-driven pumps work and pump the necessary fuel from the wing tanks to the engines.

Because our engine-driven pumps never fail, you won't ever get into a situation where you need the electrical pumps, so in the end, they're only used for tank selection.

Best regards,
http://www.dreamfleet2000.com/gfx/im...FORUM_HANS.jpg

[mamo]

Yes but with crosfeed off, an engine can't start with its wing tank and the center tank empty (while the other wing tank full).
You can check on the manual relative to the fuel, there are no permanent connection between engines and all the other tanks.
That's why I say the switchs on the overhead, relative to fuel selection, are fake.
By the way, I said in my first post that hydraulic would be hard to simulate in FS2002 but I noticed that this is done in PIC767: when all hydraulic switchs are off, the ailerons and rudder can't move any more. One more time, these switchs are fake.

I think that these are few things that would make DF737 nearly perfect.
Maybe in a new patch :)

Best regards.

[HartmannH]

That fuel thing is not fake, it's a bug. If we ever do another patch it will be part of this.

The hydraulics are intended to be fake. I know how to keep the flaps, rudder, ailerons, elevators, spoilers and gear in their current state so they don't move when no hydraulics are available. We made this decision due to performance reasons since the necessary checks need to be made in every single gauge cycle (18 times a second).

Best Regards,

http://www.dreamfleet2000.com/gfx/im...FORUM_HANS.jpg

[ET]

OK, we end up now in the hydraulics.

The B737 can be flown manually without hydraulics.
The mechanical inputs, which gives an input to the hydraulic actuators of the ailerons and elevators can also give an input to these flight controls. That is the reason that the ailerons and the elevators have servo tabs for assistance.
However the rudder can only operated hydraulically. That means hydr sytem A and/or B or standby hydraulic.
Flaps can be operated hydraulically and/or electrically
The leading edge slats and flaps by hydr. system B or standby hydraulic or via the power transfer unit, which uses hydraulic pressure of the A system. The trailing edge flaps by system B or electrically.
Spoilers are operated only hydraulical.And kept retracted mechanically to prevent floating spoilers.
The gears operates normaly with system A and can only be lowered mechanical. (i thought there is a manual gear extension function in FS2002)
So, in case of hydraulic failure the B737 can fly and land safely. Regards Erwin.

[Lou_Betti]

Indeed correct, and as also explained in our Operations Manual. :-)

Regards,
[link:www.dreamfleet2000.com|http://www.dreamfleet2000.com/gfx/im...FORUM_LOU.jpg]