Ok... here is my data so far.3 attachments.1) overall diagram of dc-9-41 fuel system (fairly accurate)2) flow diagram for logic code -> fuel_selector_set (left eng only)3) txt file of my fuel system XML code so far. by no means complete and largely untested ...I'm still trying to think this out on paper.Also, This data has been sent to another person (a DC-9 pilot) but, it sometime takes us a week or two to here from each other. His input may change some of the diagrams.Please go to it!Thanks,Johnhttp://forums.avsim.net/user_files/30647.jpghttp://forums.avsim.net/user_files/30648.jpg

John, Fun !!!! Isn't it ??? Took a look at your code ( zoned in on the Xfer part ) and found this: (L:FUEL_AUX_SW_STAT,enum)(>K:SET_FUEL_TRANSFER_OFF)(>K:SET_FUEL_TRANSFER_OFF)(L:FUEL_AUX_TRANS_ACTIVE,bool) if{ (>K:SET_FUEL_TRANSFER_FORWARD) } els{ (>K:SET_FUEL_TRANSFER_OFF) }I donot remember seeing or trying to command something within a setting so I took your code and rewrote it to test drive this type..(G:Var1)3 (>G:Var2)2 (>G:Var2)1 (>G:Var2)Well... It doesn't work. At least on my side. So.. You may want to rewrite this section..Possibly ??? : (L:FUEL_AUX_SW_STAT,enum) 2 == ! if{ (>K:SET_FUEL_TRANSFER_OFF) } els{ (L:FUEL_AUX_TRANS_ACTIVE,bool) if{ (>K:SET_FUEL_TRANSFER_FORWARD) } els{ (>K:SET_FUEL_TRANSFER_OFF) } }I am assuming the questions at the top of your .txt doc were for Stellan Hilmerby as they pertain do the 9-41..Hope this helps Regards,RomanGREEN BAY PACKERS][/i :-ukliam :-beerchug

Roman,Moving the "SET_FUEL_TRANSFER...." commands outside of a the case statement worked! The fuel transfer perfectly from the Center2 to the Center1 tank. Thanks,I've been testing my own code, based on much of our discussions, and I'm happy with the way things are working. I still have more to do but it does not seem so difficult now. (see attached file for my latest coding)I have to ask this basic question again, to anyone: What exactly is the problem when using the X-Feed command while you are using LeftMain and RightMain tanks? What is really happening when you substitute them with the External1 and External2 tanks ...which I'm being told "fixes" the X-Feed bug?Thanks,John