Thank you for your reply :)
I'll try to run other tests on fuel valves behaviour, but i bet it would not work properly anyway.
I like to fly this aicraft, and i do not doubt the flight model is correct, tough i'm really disappointed about the lack of systems modeling, after all c130 is a complex machine, so i should expect a complex management of it.
It seems like the entire programming effort has been pointed to the graphic and effects, rather than correct system working. :'(