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Vic1

747x flap power

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i discovered that even with all hyd, elec(inc batt and stby power), Pneumatic eng/grd air off but with the engines still running the flaps would still extend /retract even with just one engine running they still functioned normally and with no slow down, so i could not figure out where the power is coming from for them still to work. Is this realistic or is it a known issue? As far as i am aware the flaps normally use hydroulic power but can also be electrically driven so if there is neither of the sources available i would have thought they would not opperate.Kav

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so if there is neither of the sources available i would have thought they would not opperate.And you would be correct in that thinking :-hah So, just to confirm... APU and Eng Bleed off? Ground power (not connected or available) and engine GCB's off? Hydraulic Demand pumps (#1 & #4) and engine-driven pumps set to OFF?Things to note:If you kill electric power, bleed (duct) isolation valves will remain in the last position. Select/deselect them before you turn power off.The AUX Hydraulic pump(s) take power from the Ground Handling Bus, so I believe the Aux Pumps will run if External Power (or APU) is AVAILable (even if EXT or APU power is NOT selected ON in the cockpit). However, the flaps should not run in this scenario because there would be no power to the Flap Control Units to run the flaps (with the flap lever) electrically. Also, the Alternate Flap system needs main bus power.Having said this, this topic may have been raised before (and hopefully noted by the PMDG programmers).Cheers.Q> イアン

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Q-it's been noted and Mantis'ed if you remember. ;-) The problem was that FS does not allow for variant timings in flap movement. (We could fake that with our own animations, but the AoAs would change differently from what the display would show, making the flight model inconsistent with the visuals).

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Hi, Lefteris.I think Kav was more worried about the flaps moving without any power source more than flap speed. Unfortunately, I don't have FSX, so I can't check this out for myself.Maybe Robert(?) could look at the elec/hydraulic power logic behind flap deployment?Cheers.Q>

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Yes that is correct it was just about the fact that the flaps still worked with all the systems off but engines running not the falp speed this did not change through out my experimenting , and i did try it with every possible combination , starting from all on ,hyd, pnum bleed air, elec gens grd pwr etc and i turned them off one by one whilst ret/ ext the flaps and none of it made any difference, to the point that all hyd pumps aux eng driven pumps were off elec gens were off grd pwr off, and all but one engine running(yet not suppliying anything elec or air, still the flaps were working fine. I allowed the hyd pressure to drop and still no problem as long as the engine was running, even the bus ties were discon and finally bat off and stby off.kav

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ive just tested it again to make sure and i tried every configeration and finally ensuring that there was no grnd power/air available by unticking the menu selection which i confirmed in the lower eicas ecs page. The flaps remained functional throughout at the normal speed as long an engine was running. I did how ever discover somthing else in the process as after i shut down the only running engine the flaps still moved in both directions, very slowley but they still crept to extend and retract for approx 5 mins after shut down, i could hardly see the movement unless i zoomed right in this occured for some time after the engine was shut down despite the fact that and reading from the engine had long since returned to zero , in fact there were no readings activity showing on any flight deck system at all nor had there been since they had all been switched off long before the final engine was shut down. i was still able to fully extend and retract them during the phase.I assumed that there was still residue energy of some sort remaining in the system in reality yet i would have thought this would show up in the cockpit as te pressure was drained out. This seccond issue is realy of little importance except to say that it may be connected to the main issue of plaps moving with no power source available that is why i mentioned it kav

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