The A31X/32X series aircraft fuel system has a total of 12 pumps 6 AC powered and 6 DC powered. (with CTR tank). The AC powered pumps are powered VIA the main AC1 or AC2 bus - these two AC busses are powered directly by #1 & #2 Gen, the APU Gen or the RAT turbine VIA the AC ESS bus.
In order to protect the aircraft's power systems in the event of fire and to limit electically generated smoke - the Main AC1 and AC2 busses are in load shed - they drop current loads VIA opening contactors feeding the busses.
In this configuration, GEN1 supplies AC to the wing fuel pumps directly - bypassing the main busses altogether - the AC pumps remain powered directly.
In the total loss of AC1 and AC2 bus, we still have 4 (2 per wing tank) DC pumps available. In smoke configuration - only the DC and AC essential busses are powered - feeding power through overhead CB panel to equipment.
According to the schematic, if you have a smoke condition, the #1 generator is required for AC fuel pump operation.
Have I helped or muddied the waters ?
regards
Last edited by vapilot2004; 2nd Oct 2005 at 21:33.