8 feet MK1 12-inch x 12-inch tower truss ground support components. In order to properly use ground support systems, the truss must be level during lift and at trim. The first step when erecting a ground support system is to select a site which has a minimal difference in grade. Sites with large slopes or mounds and depressions should be avoided or leveled prior to erecting the system. Once a level site is selected, the locations of the bases should be determined. A firm foundation is required under each base which will not settle under heavy loading even in the presence of moisture. The user should have an understanding of what loading is going to be present at each tower base as well as the bearing capacity of the surface on which the tower base is supported so that the bearing capacity is not exceeded. Plywood or steel plates or both may be required under the tower bases to provide less concentrated loading to the ground directly under the base screw jacks.