BAW958 Posted June 27, 2016 Report Share Posted June 27, 2016 Hi, I did a mistake in cockpit preparation. I had fuel in center tank and wing tanks. But i forgot tu switch on de pumps for center tank. After two ours of flight the wing tanks were running out of fuel and the engines went out. After a few minutes i came back to the simulator and the autopilot was off duty and also autothrottle. The plane was in a descent and turned to th right side. I stabilised the plane and tryed to restart the engines with fuel in the center tank only. APU could not be startet for some reason. Of cours i switchted the center tank fuel pump to "on" . But i could not start the engines. After a short time i lost also the power of the batterie. So i tryed to land without any power. I tryed to lower the gear by using the three levers behind the pedestral. No effect. So did a very hard landing beside the rwy. My question is: Is it normal that i can not restart the engines with center fuel only? Why did i not receive any failure because i had not engaged the fuel pumps for center tank? Greetings markus Quote Link to comment Share on other sites More sharing options...
wiloghby Posted June 28, 2016 Report Share Posted June 28, 2016 (edited) Yes, this is the normal and correct modeling. The APU receives fuel from the left tanks. If you can still operate the pumps from the hot battery bus, you can open the crossfeed valves and pump fuel from the center to the left tank to get the APU started In your case where the situation has unfolded while unmonitored, your best bet is to look for a good spot to put the plane down Please read this page at the very least before proceeding: http://www.b737.org.uk/fuel.htm Edited June 28, 2016 by wiloghby 1 Quote Link to comment Share on other sites More sharing options...
Litjan Posted June 28, 2016 Report Share Posted June 28, 2016 9 hours ago, BAW958 said: Hi, I did a mistake in cockpit preparation. I had fuel in center tank and wing tanks. But i forgot tu switch on de pumps for center tank. After two ours of flight the wing tanks were running out of fuel and the engines went out. After a few minutes i came back to the simulator and the autopilot was off duty and also autothrottle. The plane was in a descent and turned to th right side. I stabilised the plane and tryed to restart the engines with fuel in the center tank only. APU could not be startet for some reason. Of cours i switchted the center tank fuel pump to "on" . But i could not start the engines. After a short time i lost also the power of the batterie. So i tryed to land without any power. I tryed to lower the gear by using the three levers behind the pedestral. No effect. So did a very hard landing beside the rwy. My question is: Is it normal that i can not restart the engines with center fuel only? Why did i not receive any failure because i had not engaged the fuel pumps for center tank? Greetings markus Hi Markus, yes, once you loose AC power (engines off) you can´t get the fuel from the center tank... The center tank fuel pump low pressure warning is disabled if the switches are off. Some thinking has to be done by the pilots on this plane, this is not an Airbus . You should be able to lower your landing gear with the manual gear extension, we currently have a bug where this doesn´t work when you don´t have battery power. We will fix that. Jan Quote Link to comment Share on other sites More sharing options...
BAW958 Posted June 28, 2016 Author Report Share Posted June 28, 2016 Hi, thank you for the answers and the link. best. greetings Markus Quote Link to comment Share on other sites More sharing options...
Dreamboy Posted August 9, 2017 Report Share Posted August 9, 2017 (edited) Shouldn't the scavenge pump allow to move fuel from center to left tank and restart APU? Edited August 9, 2017 by Dreamboy Quote Link to comment Share on other sites More sharing options...
Litjan Posted August 9, 2017 Report Share Posted August 9, 2017 The scavange pumps will only trigger if you turn the center fuel pumps from ON to OFF. I am not sure if the center pumps need to actually run to trigger the scavange pumps, or if you merely have to move the switch. I am also not home right now, so I can´t look it up, but I doubt that the scavenge pumps are powered through the batteries, so once your generators drop off line (like in the scenario above), they would not run, either. Cheers, Jan Quote Link to comment Share on other sites More sharing options...
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