September 17, 201114 yr With the NGX on the ground, APU bleed on with both engine bleed valve switches off, switching both AC packs off causes the bleed duct pressure(s) to drop to ~9 PSI. Switching either pack to auto or high causes the bleed press to climb to ~38 PSI. With APU bleed, and both bleed valves and both packs shut down, I expect to see a fairly high press, which should then drop when either/both packs are turned on. Oddly, selecting either start switch to GND also causes the bleed press to climb from this configuration. Bob Scott | President and CEO, AVSIM Inc ATP Gulfstream II-III-IV-V Sys1 (MSFS20+24/XPlane12+11): AMD 9800X3D, water 2x240mm, MSI MPG X670E Carbon, 64GB GSkill 6000/30, nVidia RTX4090FE Alienware AW3821DW 38" 21:9 GSync, 2x4TB Crucial T705 PCIe5 + 2x2TB Samsung 990 SSD, EVGA 1000P2 PSU, 12.9" iPad Pro Thrustmaster TCA Boeing Yoke, TCA Airbus Sidestick, Twin TCA Airbus Throttle quads, PFC Cirrus Pedals, Coolermaster HAF932 case Sys2 (P3Dv5/v4): i9-13900KS, water 2x360mm, ASUS Z790 Hero, 32GB GSkill 7800MHz CAS36, ASUS RTX4090 Samsung 55" JS8500 4K TV@60Hz, 3x 2TB WD SN850X 1x 4TB Crucial P3 M.2 NVME SSD, EVGA 1600T2 PSU Fiber link to Yamaha RX-V467 Home Theater Receiver, Polk/Klipsch 6" bookshelf speakers, Polk 12" subwoofer, 12.9" iPad Pro PFC yoke/throttle quad/pedals with custom Hall sensor retrofit, Thermaltake View 71 case, Stream Deck XL button box Sys3 (DCS/P3Dv4/ATS/ETS): AMD 7800X3D, MSI MPG X870E Carbon, Noctua NH-D15S, 64GB GSkill 6000/30, EVGA RTX3090 Alienware AW3420DW 34" 21:9 GSync, Corsair HX1000i PSU, 4TB Crucial T705 PCIe5 + 2TB Samsung 970Evo Plus, TM TCA Officer Pack, Saitek combat pedals, TM Warthog, TM RS300 FF wheel/pedals, Coolermaster HAF XB case
September 17, 201114 yr This is actually correct, I believe. The APU supplies bleed air as needed. If theres no demand for air, it drops the pressure accordingly.
September 17, 201114 yr Hi Bob, This is because the APU only provides what is demanded by the system. When you switch off the packs you don't need bleed air, so the APU reduces the bleed air output to save some fuel.The same when you start the engines, you need a lot of airflow, so the duct pressure is increased by the system. But there are some other threads about this fact.Try search them, if want more information. PS: First I thought it is a bug too. ;-) http://forum.avsim.net/topic/342066-duct-pressure-on-startup/page__hl__duct+pressure__fromsearch__1 Cheers _________________________________________________________________________ With best regards Paul Benke Athlon II X4 635 2,9GHz, Gigabyte GA870A-UD3, 2x 2GB DDR3-1333, Gainward GTX460, 2x 500GB HDD Win7 64bit, FSX SP2
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