This manual has been written with the intention of supplying the necessary instructions for the installation, operation and maintenance of Wright Aircraft Engines. A thorough knowledge of the correct installation, operation and maintenance routine enables the operator to get the best service from his engine. Under the heading “Troubles” tables of the more elementary troubles and their causes are submitted with the object of reducing wasted time and increasing the reliability of the engine. This section should be read by the experienced as well as the new operator. The life of the engine depends upon the proper care as well as upon its proper operation. For the pilot are included instructions for handling the engine and for the hangar personnel hints on its daily care.