To solve the problem always select GS/FF. Then in order to calculate fuel back to the beach in this mode do your PERF INIT as normal, however in PILOT GS/FF mode. Then in order to calculate fuel flow select FUEL MANAGEMENT from the PERF page. In the top right hand corner you will see fuel flow. Select the fuel flow you require into the scratchpad. For planning purposes I would select 950 to 1000lbs (or in Kg in this case). Then paste this value on top of the fuel flow value in the top right hand corner. This is the value that the FMS will now use to calculate fuel burn. Then you can select delete into the scratchpad and paste it on top of the fuel quantity, this will then display the current gauge value.
Go to your PERFORMANCE page and you should now see fuel remaining at each point based on this new fuel flow value.
In flight you can adjust this value if you find that you are burning less or more than this value.
What we usually do is when we get into cruise flight we take a quick look at the pressure altitude, weight and temp and get the fuel flow for those values from the flight manual. This gives us a TAS, torque setting and fuel flow value. We then paste this value into the FMS as descibed above and reset the fuel quantity to the gauge value as described above in order to get a more accurate estimate in flight. (We have all this simplified as a program for excel for the PDA - Therefore we just plug in weight, pressure alt and temp and we get Torque, TAS, and fuel burn)
Hope this helps.
Last edited by platinumpure; 19th Jun 2007 at 01:53.