Power for the Zeppelin NT's propulsion systems is provided by a trio of Textron Lycoming IO-360 boxer aviation engines, fueled by standard aviation gasoline. These engines are mounted on the sides and rear of the structure itself to provide optimum efficiency; this arrangement also increases in-flight comfort due to reduced levels of propeller noise and vibration. In addition to thrust, each engine also provides maneuverability via their swiveling propellers; the two forward engines are equipped with hydraulically-actuated tilting propellers which are usually aligned horizontally, but can be turned 90° upward or 30° downward, while the aft engine powers a fixed lateral propeller. Each engine is furnished with separate fuel tanks and supply systems that typically operate independently of one another.