Cazatou, One reason I can't be sure is that I never heard the precise term "anti-spill valves" before, that's why I can't be certain where they are.
However, I do recall that the fuel tank vent lines are plumbed to cross over to the opposite side of the airframe, so that if the aircraft rolls onto its side, fuel shouldn't drain out directly from the vents. The vent outlets are visible on the airframe.
Also, it's nearly sixteen years since I flew the type and the aircraft underwent an update after I moved on. Valves may have been fitted during that update; I don't know.
Last edited by ShyTorque; 9th Dec 2009 at 23:02.
Reason: spelling error corrected