This document covers the general requirements for hydraulic aircraft jacks. It can be applied to tripod, unipod, and axle jacks that may be used on open ramp areas as well as in the aircraft hanger. Throughout this Aerospace Standard, the minimum essential criteria are identified by the key word shall. Recommended criteria are identified by use of the key word should. Deviation from recommended criteria should only occur after careful consideration and thorough service evaluation have shown alternate methods to provide an equivalent level of safety. The term vertical load throughout this Aerospace Standard is defined as the force imposed on the aircraft jack at the airframe jack point.