A B737-700 flight crew took exception to the manner in which center tank ballast fuel; required when...

Attributes
ACN	1121932
Time
Date	201310
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Fuel Booster Pump
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 134 Flight Crew Type 17500
Person 2
Function	First Officer
Experience	Flight Crew Last 90 Days 155 Flight Crew Type 7000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural MEL Deviation - Procedural Published Material / Policy Deviation - Procedural Weight And Balance

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.