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Guest Ramsberg

FSBUS CCC fuel system example

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Hi guys!Worked a little bit more on my fuel system for the 737:http://forums.avsim.net/user_files/72249.jpgHeh, kind of getting to the point where it can be hard to grasp. Some comments might be needed:The system uses three tanks with 2 pumps each. All pumps have a 3 seconds pressurization delay. During that time the "Low Press" light is lit. After a pump on a tank with fuel in it is running, that side of the fuel system is pressurized.The Crossfeed should work a the real one...The APU-Press output requires the Left Aft pump to be on and the left wing tank to have fuel...Question: The DC fuel pump for the APU, is it contolled by the Left wing aft pump switch or is it automated?The outputs arent "real" yet, the will be used as input variables to the rest of my system...Left to do is the refueling and emergency fuel dump... But thats low priority.Cheers!Olle Ramsberg

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:(can you do this for F50 as well ? :Dno, nvm. i'll show all this to Espen and talk with him about how we can implement this CCC into my sim as well cuz this CCC seems to be so very very priceless OMG !soon we'll not need any more panel for fs!only te gauge faces if they are shown in the cockpit.

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Can you tell me how I make this thing work:x y result1 0 11 1 00 1 00 0 0I need this plenty of times. The Batery (x) switch will make some leds go on (dark cockpit) which need to go off when i turn on the system by pressing the appropriate button (y).However, as long as the batery switch is not on, pressing the button (y) should not have any effect.

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Hmm, tricky...I think this will do it:http://forums.avsim.net/user_files/72333.jpgCase by case:1. If X=1 and Y=0, result will be 12. If X=1 and Y=1, result will be 03. If X=0 and Y=0, result will be 04. If X=0 and Y=1, result will be 0Think it will work...Give me more tricky stuff! :-) Cheers/ Olle R

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OMG :)indeedit seems simple once you see it.i was trying all kinds of things here with the RS and such .. omgif you look at the table I made, you see that only the Y column is inverse from the default AND table. so indeed inversing the input to Y is the solution :)tnx!

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No problem :-)Many may think im nuts, but I enjoy this :-)For those who are as nuts as I am, I have a nice "game" called Bugbrain, which is a very good starting point if this kind of "low-level-program-thinking" is hard do understand.Take a look at :http://www.biologic.com.au/bugbrain/Its really funny and challenging, start out with the simple tutorials and challenges and finish with programming "move, smell and find food to survive"-programs for worms and ants etc.../ ramsberg

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Olle:>>Question: The DC fuel pump for the APU, is it contolled by the Left wing aft pump switch or is it automated?Only the 737-100 (and, perhaps, some 737-200's) had a DC fuel pump, and it had its own manual switch on the panel. The -500 has a DC "booster" pump, which is controlled by a low pressure sensor in the fuel line.On all other 737 models, the APU is fed from the left tank fuel pump common outlet. To provide pressurized fuel to the APU you must either turn on the left pump or turn on the right and open the crossfeed. However... the APU can be run with no fuel pump running, except that at high loads (hot day with the AC running, for example) the APU may 'hunt' as the APU fuel vacumn won't be able to suck enough fuel to keep it running at high load.This info from a senior Continental Captain that I asked today after a flight from IAH to OAK. (737-900 btw)Richard

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Cooool, thanks for the info man!So, is that true for the engines too? Are the engines runable without the booster pumps? I know that there are fuelpumps in the engine propelled by the engine, but are they suffient for running the engines alone? If so, when are the boosterpumps needed?Cheers!Ramsberg

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>Cooool, thanks for the info man!>>So, is that true for the engines too? Are the engines runable>without the booster pumps? I know that there are fuelpumps in>the engine propelled by the engine, but are they suffient for>running the engines alone? If so, when are the boosterpumps>needed?>>Cheers!>Ramsberg I dont know about jets, but for example Piper Archer has an electric boost pump for fuel. There is a mechanic one that is driven by the engine, the booster is used during takeoff and landing (worst phases of flight to have an engine failure) - in case the mechanic one breaks, there is still an electric one left supplying fuel.It is also turned on when you switch tanks on cruise. Once you have switched the tank and verified the fuel pressure is OK, you switch the pump off.//Tuomas

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I don't know..... I'm flying next on Wednesday of next week, I'll ask then if you haven't heard already. My 'gut feeling' would be that the engines can probably run using just their internal pumps but they might not be startable without the electric pumps. (much like in the Archer example below - you'd start the electric pump to put some fuel pressure in the system to start, but it would usually be off in normal service) That's probably moot anyway - I'm sure that MEL is at least one pump each side, so if you didn't have them you wouldn't even be trying to start an engine. The APU doesn't have an internal pump which is why it would have a fuel starvation issue under load - the fuel suction comes only from the venturi effect of the injection.Richard

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