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B777 Why is so quiet while turning R demand pump on?

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B777 Why is so quiet while turning R demand pump on?

Old 10th Oct 2023, 11:00
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B777 Why is so quiet while turning R demand pump on?

i found when we need to pressurize the hydraulic system before pushback, after turning on the R demand pump to auto, there will be quiet in cockpit for a while ( sounds like fans stop working), i am confused...
any logic within the demand pump, fans and noise in that situation. thanks a lot!!!!
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Old 10th Oct 2023, 17:57
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Originally Posted by sm165019117
i found when we need to pressurize the hydraulic system before pushback, after turning on the R demand pump to auto, there will be quiet in cockpit for a while ( sounds like fans stop working), i am confused...
any logic within the demand pump, fans and noise in that situation. thanks a lot!!!!
ELMS load shedding while the demand pump comes up to speed.
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Old 13th Oct 2023, 06:22
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Originally Posted by applecrumble
ELMS load shedding while the demand pump comes up to speed.
Thanks a lot, you are right. I checked the electric synoptic during turning the R demand pump to auto, there was a load shed showed. it seems that galley doesn't work or stop working at that moment.
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