B737 Fuel Center Pumps

[LEM]

It is common practice to take off with the center pumps off if the tank contains less than 1000kg, to avoid uncovering them thus getting a caution light.

But today my brother tells me they take 1000 lbs as a reference, not kg .

So the doubt arises in my head...

[wobblyprop]

see this thread also,

737-800 pump (http://www.pprune.org/forums/showthread.php?s=&threadid=101245)

But i believe it is 500kg, which is roughly 1000lbs

[Waggon rut]

centre pumps off 2300kg for takeoff on the NG, 500kg for climb and cruise and 13 or 1400kg for descent.

[Rotates Lowly]

The limit is 453 kg on the -200 and Classics, which equals 1000lbs

[Flying_Tuur]

It is lb... and kg...

5000lb, 3000lb and 1000lb to be correct. In Europe this sometimes noted as 2300kg, 1400kg and 500kg.
Conditions as posted by Waggon rut.

FT

-- edit for spelling error --

[tykon]

500kg and under roughly you pilots turn the pumps off, so it is true..

[loewe]

For 737-3/4/500, center fuel pump must be off during take off if the fuel in the center tank less than 1000 lbs or 453 kgs.

[avioniker]

Okay, here's the FAA's January 2003 version of the AD:

Airplane Flight Manual (AFM) Revision: Model 737-600, -700, -700C, -800, and -900

(b) For Model 737-600, -700, -700C, -800, and -900 series airplanes: Within 4 days after receipt of this AD, revise the Limitations Section of the AFM to include the following (this may be accomplished by inserting a copy of this AD into the AFM):

"Certificate Limitations

The center tank fuel pumps must be OFF for takeoff if center tank fuel is less than 5,000 pounds (2,300 kilograms) with the airplane readied for initial taxi.

Both center tank fuel pump switches must be selected Off when center tank fuel quantity reaches approximately 1,000 pounds (500 kilograms) during climb and cruise or 3,000 pounds (1,400 kilograms) during descent and landing. The fuel pumps must be positioned Off at the first indication of fuel pump low pressure.

The CWT fuel quantity indication system must be operative to dispatch with CWT mission fuel.


Note


The CONFIG indicator will annunciate when center tank fuel exceeds 1,600 pounds (800 kilograms) and the center tank fuel pump switches are Off. Do not accomplish the CONFIG non-normal procedure prior to or during takeoff with less than 5,000 pounds (2,300 kilograms) of center tank fuel or during descent and landing with less than 3,000 pounds (1,400 kilograms) of center tank fuel.


Note


In a low fuel situation, both center tank pumps may be selected On and all center tank fuel may be used.

If the main tanks are not full, the zero fuel gross weight of the airplane plus the weight of center tank fuel may exceed the maximum zero fuel gross weight by up to 5,000 pounds (2,300 kilograms) for takeoff, climb and cruise and up to 3,000 pounds (1,400 kilograms) for descent and landing, provided that the effects of balance (CG) have been considered.

If a center tank fuel pump fails with fuel in the center tank, accomplish the Fuel Pump Low Pressure non-normal procedure.

When defueling center or main wing tanks, the Fuel Pump Low Pressure indication lights must be monitored and the fuel pumps positioned to Off at the first indication of fuel pump low pressure. Defueling with passengers on board is prohibited.

The limitations contained in this AD supersede any conflicting basic airplane flight manual limitations."

[LEM]

Ok, let's sum up: there's an official AD limiting the use of fuel, but on the NG only.

On classics and originals there's no limitation : we are allowed to burn routinely ALL center tank fuel.

Although we can takeoff with all 6 pumps on, it is customary here to takeoff with the center pumps off if the tank contains less than 1000 kg , to avoid uncovering them because of the acceleration and body angle involved while taking off.

That's simply to avoid a nuisance blinking light, which would be no big deal anyway.

We turn the pumps on again following the completion of the After takeoff cklist.

I say again, this is customary only and based upon an unofficial tradition.

All this in my understanding.

Questions: Is this practice the same elsewhere?
If yes, do you take 1000kg as a reference or 1000 pounds?

That was my original question, and regards classics.

Thanks.

[fruitloop]

LEM,
Sorry bloke but it isn't quite 'black or white' regards the classics.Some (not all) companys have either complied with the alternative action (crew ops etc...)regards total usage of fuel in centre tank or allowing a "figure"to remain ......I wish it was as easy as yes or no !!!
Cheers

[Flight Detent]

Hi Guys,
The correct figue is 1,000 LBS, which equates to 453 KG in some books.
It also says that if 453 KG or more fuel remains after attaining level flight, the CTR TANK pumps must be switched ON again to use all the fuel.

Cheers:ok:

[wellthis]

Where I have seen, it's been 1,000 lbs unwritten rule/airmenship on Take-off to prevent the possibility of pump damage and the nuisance of the recall light associated with high deck angles. As you said, normally back on at 10,000'(or cruise) to burn all the fuel. Hope this helps.

[Wizofoz]

The 100lbs/453KG is a FOM limitation, below which the centre pumps MUST be off for takeoff. 1000kg is sometimes used is practice fo the reasons related to above.

[LEM]

wellthis, :ok:

Wizofoz, I have never seen such a limitation in any manual.
As it is now clear that this thread regards classics, could you quote the source of your information?

I've also got the impression some people are confusing the 453kg figure (which is published for balance and wing bending) with this matter.

Thankyou all.