A washing unit for turboprops of aircraft is disclosed, which comprises a hydropneumatic accumulator suitable for supplying, at a controlled pressure, a washing fluid contained therein, and a filling member, motorized and manual, for feeding the washing fluid into the accumulator. The accumulator may be connected alternatively to the motorized filling member or to the manual filling member. A manually actuated device is also provided for pressurization of the accumulator, so that the washing unit can be used both in areas equipped for this operation and in areas not so equipped.