B737-700
Flight Crew Last 90 Days 134; Flight Crew Type 17500
Workload; Human-Machine Interface; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
Aircraft; Procedure
Aircraft was released under an MEL for an inoperative right center fuel tank boost pump. The Dispatch Release does not list the center fuel as ballast; but the loading schedule must plan for it as ballast; per the MEL. When applying this MEL; there will be errors between the loading schedule; weight and balance calculator; and FMC calculations requiring non-standard procedures to correct aircraft weight calculations affecting proper weight/balance and flight performance data. The procedure to plan for the center tank fuel becoming unusable is required on the load sheet; but not the Dispatch Release (usable center fuel). The procedure to use revised zero fuel weight in the weight and balance calculator and FMC creates calculation errors. The OPC fuel weight will not match the normal listing for fuel on the load sheet and the FMC will double count the center fuel in its gross weight calculation creating flight performance errors. To make the load sheet/weight and balance calculator data match the FMC data; we had to input two different ZFWs. Please reference IR # for detailed analysis.
[No additional information was provided in the secondary narrative.]
A B737-700 flight crew took exception to the manner in which center tank ballast fuel; required when a boost pump is inoperative; is accounted for in performance and flight planning programming.