B737NG fuel loading limitation

[lospilotos]

Hi!

One of the limitations stated in FCOM1 is "Main tanks 1 and 2 must be full if center tank contains more than 453 kgs."

I often see fuellers switching on all three fuel switches from the beginning thus getting 3-4 tonnes in the center tank before the main tanks are full. Is this a problem?

Just to be clear, I´m not talking about when/how to operate the center fuel pumps, this is a structural and W/B issue (I think...)

/L.

[john_tullamarine]

Typical inflight fuel restriction for most aircraft bigger than puddle jumpers.

Usual reason is for wing bending relief. That is to say, the fuel in the outboard wings tends to reduce the extent of wing bending in the vertical (pitching) plane for a given flight load compared to having more of the fuel inboard (or in fuselage/centre section) tanks.

Unless there is a specific refuel limitation, it is not significant how the actual refuel is performed.

[BOAC]

Like JT says, plus possible c of g issues. 'All 3 switches on' is fine in practice when the intention and application is to load correctly, but this is why ALL fuel loading should be monitored by qualified personnel to ensure that the centre tank is switched off at the right level and that the wings load the while. The only problems I ever had were in TLV once with a 734 with aux tank where the fueller was loading the aft aux before the rest which was a strict no-no, and with BA's liking for putting a calculated amount into the centre BEFORE the wings are full which on a couple of occasions meant I had to over-fuel to get the wings full.

I guess in strict accordance with the limitation it would be correct to load wings first.