Tronair offers the 50111ZZG mobile driven hydraulic power unit (HPU). The unit provides a source of clean, pressurized hydraulic fluid for performing required aircraft maintenance. A two cylinder, tier II gasoline engine drives a pressure compensated piston pump. Filters are provided on the pressure and return systems. A bypass (dump) valve allows starting and stopping of the unit under a no-load, safe condition. The unit may use either the aircraft or on-board HPU reservoir. The unit is equipped with cooling for continuous operation, electric start engine, fully instrumented operation panel for both engine and hydraulic systems, an eight hour fuel tank and a heavy duty towable frame designed for off-road terrain.