Fuel quantity indicator 737

[Popolama]

last time i had an error 7 on the center tank indicator which was showing zero.
in the MEL error code 7 says it's a "calibration unit failure" whereas in bill bulfer's cockpit companion it says with an error code 7 showing normal it's a contamination/water in compensator.
which one do you think it's correct ?
can you dispatch with the center tank indicator showing 0 (error 7) or completely inop ?

we were able to fly the bird but there s a little trick ....any ideas ?

[B73567AMT]

The B737 Cockpit Panel Notes is a guide...not God. It was written by a pilot, and while I must admit he did his homework, there are SEVERAL things incorrect in there. And most of the incorrect iteas are the informal "If this happens, then this is most likely the case" statements. This is one of them.

Just double checked, and the error Code 7 is for a Calibration Unit Failure. Has nothing to do with the Comp probes. The Calibration Unit is attached to the back of the Fuel Quanttity Indicator(s). It's called a DCTU (Digital Trim Calibration Unit).

If the aircraft is flying along and the Calibration Unit has a failure, the qty will continue to show. There will be a "ERR" shown. The Code 7 and "0" fuel qty only happens when the unit fails during power-up (or has failed).

Yes, the aircraft can be dispatched with an inoperative Center Tank Indication System. The Center Tanks on the B737 cannot be measured using fuel sticks, so the tank must be filled with a known qty and the Fuel Used Indicators must be used to determine Center Tank Qty.

Hope this helps.

[DDG]

B73567AMT,

JUST TO CLARIFYThe Center Tanks on the B737 cannot be measured using fuel sticks, so the tank must be filled with a known qty and the Fuel Used Indicators must be used to determine Center Tank Qty.
THIS IS TRUE FOR CLASSIC B737`S,HOWEVER THE B737NG IS FITTED WITH DRIPSTICKS IN THE CENTRE TANK.

REGARDS DDG

[B73567AMT]

Yes you are correct.
Didn't think I had to clarify since we were only talking about the B737 Classic...but that statement could mislead someone jst passing through.

Sorry.

[Popolama]

thank you B73567AMT and DDg for your answers.
btw do you have to deactivate the fuel summation unit ? according to the MEL it states it's only for unit 6,7 and 10 (so you ll be able to put in the fuel qty) but what about unit 5 ? is it important that you deactivate the FSU even though you won t be able to put in the fuel QTY ?

[bacem]

For all B737 classic you have to disactivate the fuel summation unit (just located behin copilot head). For Fms update 5 you will not be able to enter the ZF, fuel qty, climb &cruise speed and CG in the FMS. You will use the MCP because there will be no VNAV available. No way points estimation. You need to use the QRH to determine the optimum altitude and Vref for landing.
For FMS update 7, 8 & 10x you have the possibility to enter the fuel quantity manually in dashes and you will have almost everything, but any way the Fuel summation unit should be disconnected.