B737NG centre tank ground transfer

[Telstar]

Recently a fueler made an error fueling my aircraft. He proceeded to put 700kgs in the centre tank and 2500kgs in each main tank when we had asked for 5700kgs block fuel. This was in breach of the airframe limitation which requires the wings tanks to be full if there is more than 453kgs in the centre tanks. As we were at an outstation with no engineering support the easiest solution I could find was to fill the main tanks. As I work for an airline that monitors the carriage of "excess" fuel, that is fuel carried above the flight plan fuel, a report was submitted by me explaining the situation. My Chief Pilot reponded in an a sympathetic manner however he noted that there is a method to transfer fuel from the centre tank to the mains on the ground using the defuel valve. I can't find any reference to this, and I probably wouldn't have gotten involved with it without it being demonstrated but imam just curious if there is a way to do this and how long it would take to transfer 700kgs?

[ray cosmic]

hi, I'm not current on the 737 anymore; but I had a similar situation once.
As far as I can recall, you turn a handle in the area of the reuelling panel (seperate access door) and work with the pumps and crossfeed selector from the flightdeck to move the fuel. It is pretty slow, but it works.
Sorry, I can't provide references. Is it not in Supplementary procedures?
Otherwise a mechanic at home base should definitely be able to tell and show you.
I

[Cough]

If I remember correctly...(737 classic...)

Centre tank pumps on (on fuel panel in cockpit)
All other pumps off
Crossfeed open
On refuel panel open valves to tanks 1+2
Open de-fuel valve (separate panel next to refuel panel)

Wait five mins?

Done!

[FCS Explorer]

100 points for Cough!
---------
nevertheless one question to Telstar: i assume you are the CP on this ship - and don't even know how to transfer fuel on ground......?????

[Peter Fanelli]

You don't need to have the crossfeed valve open, apart from that Cough has it correct.

FCS explorer very few 737 pilots know about this but most fuel truck drivers do.
When I was doing a stint as a fuel truck operator I had several crews stare in disbelief at the gauges as the center tank drained away after following my requested procedure.

Of course since it requires the defuel valve to be opened it can be done ONLY on the ground.

[greenslopes]

Perhaps it's time to hit the books again?
Oh, all right I'll give you a clue FCOM VOLUME 1 SP.12.3.

[cosmo kramer]

If looking at the schematics, you need the crossfeed open if you want both centertank pumps to participate in the transfer...

If the crossfeed is closed only the R CTR tank pump will pump fuel back to the fueling panel. If crossfeed is open both pump will pump fuel to the fueling panel. If you leave the crossfeed closed you might as well leave the L CTR tank pump off.

Now for another consideration. Are you allowed to trasfer fuel with passengers on board or boarding? Technically you are fueling tank 1 and 2, just from another source than usual

[Swedish Steve]

Cough

If I remember correctly...(737 classic...)

By classic you mean 3/4/500?
On the B737-200 it was the same procedure, But you had to also open the right engine spar valve, or you got no fuel to the defuel valve. The easiest way to open the spar valve was to trip the ignitor CBs, then open the fuel lever on the pedestal (HP cock). Then you forgot to reset the CBs, and the engine would not start.

[BOAC]

Once again,
200/200 Jurassic
3/4/500 Classic
6/7/8/900 NG

No 'Spar' valve on the 200 as I recall. Required No2 start lever open I think.

In reality the tank 'limitations' of which you speak are there to prevent exceedance of MZFW
and incorrect trim state, both of which could be worked around.

[rudderrudderrat]

I agree with BOAC. If the wing tanks are not full, then any fuel in the center tank must be considered as part of the zero fuel weight. From memory this was "hidden" in the MEL for operation with centre tank pump(s) inop.

Thanks for the explanations of fuel transfer on the ground.

[Flexi]

Code:

If the wing tanks are not full, then any fuel in the center tank
 must be considered as part of the zero fuel weight. From memory
this was "hidden" in the MEL for operation with centre tank
pump(s) inop.

Good point - also very well hidden in our OpsManual!

[Telstar]

Thanks for the replies. I did find it in Sup. procedures I had missed it first time around.

FCS, I asked the question, I would hardly have asked if I already knew the answer. I did my type rating in CAE which as you may or may not know is a large, multinational provider of ratings for many airlines. I also passed the tech exams and flight tests as laid out and approved by two national authorities. We could go into another debate on minimum cost minimum standards style of civilian training but I think it's been done already? Thanks for your contribution, if it's made you feel superior I'm glad to have helped.

I had never been made aware of this option, and as it had never been demonstrated to me or had I ever even seen the defuel valve before, I thought it best not to dive headfirst in to a technical procedure that I am not proficient at, a 25min turnaround is not the time to start experimenting. The Captain incidentally has over 25,000hrs on mostly Boeing types and also was in the dark about this.

[FCS Explorer]

well i was just wondering because i would not have passed my FO supervision with not knowing this.

[Haroon]

You can also balance fuel on ground just like you do in air after pulling down this red handle located right of the fueling panel (separate access door) when facing the leading edge of the right wing.

[Flight Detent]

If you're facing the leading edge, don't you mean "the starboard wing", otherwise you would be on the wrong side of the airplane!

Just joking (this time)...

Cheers...FD...

[Haroon]

Fueling station is only on one wing, you cant possibly miss it