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Guest ALT2024

744 fuel flow

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Guest ALT2024

I've just completed a long-haul in the 744, from VTBS to EGCC. I loaded fuel intending to have over 24,000lb left on arrival. The cruise was overnight so I was asleep for most of it and didn't turn off the crossfeed fuel pumps until this morning... which may be the cause of the problem I had during descent.During the descent (ROSUN1F arrival managed by the FMC in VNAV) I started to get yellow messages on the EICAS, firstly re. override pumps, and then a low fuel message even though the FMC claimed to have just under 30,000lb remaining. Over ROSUN I lost both inboard engines but was able to restart them by reactivating the crossfeed pumps. While restarting them I noticed that the aircraft went into overspeed even though it was level at FL70. I reduced speed by switching off the autothrottle, closing the throttles, re-engaging autothrottle and re-engaging VNAV.Landing was normal (if a little bumpy :-roll , my fault for landing manually:)) but during taxi the inboard engines shut down again.I guess the engine problems were caused by my bad fuel management (plenty of fuel but in the wrong places perhaps) but I'm at a loss as to what caused the overspeed.Rob

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"and didn't turn off the crossfeed fuel pumps until this morning"I'm having trouble understanding what you mean... What's a crossfeed pump? :)Did you put your joystick throttle to idle during the descent? (If you have a joystick throttle).Cheers.Q>

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Guest ALT2024

Sorry, I meant crossfeed valves. The ones you have to turn off when the EICAS says 'tank to engine'.I don't think I did set the joystick throttle to idle. I'm about to try another ROSUN1F (flying LTBA-EGCC this time with about 70nm to run to T/D). I'll report my progress.Rob

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Guest ALT2024

All ended well second time around. Perfect descent managed by VNAV with every altitude and speed restriction effortlessly met (no extra drag required). Approx. 7000lb of fuel left in each tank on landing. No fuel starvation shutdowns and no overspeeds (I made sure the joystick throttle was at idle throughout the descent).Could the original fuel problem have been caused by leaving the tank 2 and 3 override pumps on, thus draining tanks 2 and 3? It was engines 2 and 3 that kept stopping. Unfortunately after the problem flight I forgot to check the fuel remaining in each tank. I know there was almost 30,000lb total left, though.Thanks for the helpRob

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