It's been a while since I flew a King Air but what I remember about those yellow arcs is that they indicate a minimum takeoff fuel. I believe they show up on all Beech aircraft as a result of a takeoff accident in a Baron where the pilot made a rapid rolling takeoff with minimum fuel. The fuel sloshed out in the wing and unported the fuel pickup resulting in an engine failure and accident. Once you're airborne there's no restriction on using the fuel except for good judgement