The pair of propellers on each wing turn in opposite directions, with the tips of the propellers advancing from above towards the midpoint between the two engines. This is in contrast to the overwhelming majority of multi-engine propeller driven aircraft where all propellers turn in the same direction. The counter-rotation is achieved by the use of a gearbox fitted to two of the engines, and only the propeller turns in the opposite direction; all four engines are identical and turn in the same direction. This eliminates the need to have two different "handed" engines on stock for the same aircraft, simplifying maintenance and supply costs; this configuration, dubbed "down between engines" (DBE), allows it to produce more lift and lessens the torque and prop wash on each wing. It also reduces yaw in the event of an outboard engine failure. Because of these benefits, the vertical stabilizer can be reduced by 17 percent in size, while the size of the horizontal stabilizer can be shrunk by 8 percent.