Aerial firefighting dump gate system

A gatebox system for a hopper that contains fluid in a firefighting aircraft, comprising:

• a box assembly with an upper portion adapted to receive the fluid from the hopper, and having a first gate opening and a second gate opening formed through a lower portion thereof;
• a first gate hingedly connected along an edge of said first gate opening;
• a second gate hingedly connected along an edge of said second gate opening;
• a drive shaft supported within said box assembly and rotatable in a gates-closing direction and a gates-opening direction;
• a first crank arm fixed to said drive shaft and coupled to said first gate by a first connecting link, wherein said first crank arm and said first connecting link define an over-center geometry while said first gate is at a closed position, such that weight of the fluid on said first gate induces torque on said drive shaft in said gates-closing direction;
• a second crank arm fixed to said drive shaft and coupled to said second gate by a second connecting link, wherein said second crank arm and said second connecting link define an over-center geometry while said second gate is at a closed position such that weight of the fluid on said second gate induces torque on said drive shaft in said gates-closing direction, and wherein
• rotation of said drive shaft in said gates-opening direction is coupled to said first and second gates by said first and second crank arms and said first and second connecting links to open said first and second gates, to thereby enable control of the fluid flow from the hopper according to an angular position of said drive shaft.